Jump to content
Holidays
Local
Radar
Snow?

Leaderboard


Popular Content

Showing content with the highest reputation since 11/02/19 in all areas

  1. 37 points
    As winter begins to wain we must remind outselves 'peak' cold availability from the N/NE/E is still on tap for another 3-4 weeks- so although the suns height does temper any daytime low maxima - we are still in the game. Im drawn to the nice sight of the PV stretched south into Scandi around day 9 & this should continue to be out focus if we believe 18/19 can squeeze another cold spell - 06z was close but no cigar....
  2. 34 points
    I was cleaning the car about 30 mins ago & felt a tremor in the force - Must be something brewing in the models.. ( I love warm & sunny weather ) but a switch in the next 10 days could mean a last chance meeting with old man Winter...
  3. 31 points
    Hello Although we may get cold in March, the meteorological winter is almost over and the models show little signs of the deeper cold we chase. So I thought I’d discuss the winter which is passing by and speculate as to the main drivers of its synoptics. It all started to seem so promising back in November… the previous winter had ended with the beast from the east, solar activity was approaching a minimum and there were signs of an SSW event in the works. There was an apparent El Nino, which led me to forecast a backloaded winter.. but even that turned out to be wrong as the El Nino waned in recent weeks... In truth the weather in November was actually pretty interesting, we had a very sluggish and amplified weather pattern… its just the UK wasn’t in the right place so it was mild here. We then had the potential for a serious cold spell with a large Greenland block as this swingometer from November showed. The Greenland high however wasn’t strong enough and milder air eventually won out. I believe that weather patterns can be like a see-saw and had we succeeded here, the chances of a cold December would have greatly increased but it wasn't to be. Aside from a brief cold snap mid month, December was awful and very mild over many areas. Although we had an SSW late on in the month the first half of winter was very poor. I wasn’t too concerned at this point however as I was going for a backloaded winter (which as I mentioned turned out to be wrong). Aside from the brief cold and snowy spell in late January the remainder of winter so far has been a write-off to be brutally honest. So why is it going so wrong? Here I discuss some factors I believed caused its downfall 1) The failed cold spells of late November and January These periods saw some fantastic output only to be toned down to nothing closer to the time. These I believe hold some significance. As mentioned I think a northern block would have increased the chances of a cold December. Think of 2010 and to a lesser extent 1995 (which saw a very blocked November but mild at times). If the vortex is displaced it can take a long time to re-organise itself and the synoptics during later November were a golden opportunity to split it, but it didn’t materialise. SST patterns over the NW North Atlantic during the second half of January show some correlation with those of the following February and March. Therefore if later January is blocked then the following February and March are more likely to be too as mild SSTs to our west would have persisted. However as we all know, the chances of an epic cold spell vanished at this time. Some really cold uppers with charts such as those forecast below were touted but the models flipped at the last minute as the swingometer painfully shows. 2) The SSW event saw lobes of the polar vortex fall into the wrong place The SSW event in late December to early January was really strong but the impact compared to February 2018 couldn’t be any more different. One of the problems was that the lobes of the PV fell into the wrong places. I noticed a lot of posts in the cold hunt thread were really hyping up the split vortex… without considering how the locations of the PV could impact things…. Split PV forecast example but this really wouldn't work for us would it? Unfortunately all the cold air spilled into the North Atlantic… which brings us to point number 3. 3) The North Atlantic cold blob You may have heard of this as it was in the news quite a bit a few years ago. It’s clearly evident when looking at global temperature trends over the last 100 years and may be related to climate change. When looking at individual winters…. Things get even more interesting. I’ve posted the SST anomalies for March following milder winters and you can see that cold anomalies to the south/east of Greenland are a common feature. February 2019 What about cold winters? I think these are pretty clear. So are we completely overlooking ocean processes and given the pattern of increasing temperatures could we also blame climate change? Either way the anomaly pattern below shows how 2018/19 fell into the trap of recent mild winters…. The Atlantic cold blob is driven by a polar vortex over Greenland that spills cold air into the North Atlantic and fire up deep Atlantic lows but also by changes in ocean circulation which in the longer run may be influenced by increased freshwater from melting ice. 4) Climate change? Ah yes the elephant in the room. I may have mentioned it in the model output thread a while back but I believe climate change is like a loaded dice. Imagine a six being the mildest and a 1 being the coldest. In a warming climate we can expect it to be easier to tap into warm pools and harder to tap into cold. These two sets of charts sum up that point very well. Often for a prolonged cold spell we need a deep cold pool to our east to hold back the Atlantic or prevent tapping into mild air. The lack of deep cold to our east meant there wasn't much of a fight to begin with. So does this mean that we will never never never see cold again? No… not at all here is how I think things will pan out in the future. 1) Summer/ Autumn Arctic sea ice will carry on decreasing in the long run – This will decrease the temperature gradient from high to mid-latitudes and will mean patterns will become stuck for longer. I believe the NAO will be more volatile with more often than not highly +NAO winters but periods of exceptional –NAO winters will also emerge to rival 2010. Neutral NAO winters will become less common. 2) There are some suggestions that some aspect of solar activity may have an impact on ocean circulation and this may finally help get rid of the annoying cold blob if it does... but there are other factors at play too. Perhaps there is a lag and we aren’t seeing the response to low solar activity yet. 3) A switch to a negative PDO…. The cold blob in the Atlantic is also connected to some extent with the PDO too. It has often been positive in recent years whilst at the start of the decade it was strongly negative. So things may change for the better although I do believe because of climate change we will require better synoptics to tap into deep cold each year. Severe cold spells will still be a feature however and if the AMOC slows then we may see more in the way of 2010 like synoptics. All the additional heat may put the climate system under more stress and we could see a change in state (imagine pulling an elastic band, also read up on Lenton et al 2008 about climate tipping points). Is the NAO showing this increased stress with the volatility seen during the 2010s. Could the elastic band be about to snap? Either way I think the things that could have gone wrong this winter did so that’s it for another year. Perhaps the dice will throw a 1? Perhaps the scales will flip and that annoying cold blob in the Atlantic will go away… For next winter I suggest the following things to keep an eye on. 1) Keep an eye on SSTs around the NW North Atlantic and to our west. 2) When there is a future SSW event where are the lobes of the PV falling? 3) When viewing the MJO charts, how wide are the uncertainty bounds? For example on the below chart the spread is huge… so whilst the average indicates strong phase 8, it could end up anywhere….. And that brings the end of my review…
  4. 30 points
    Extracts posted last week on closed thread: The other part of the equation is the seasonal transition within the stratosphere from its winter default vortex position to its summer state. This is bound to increase -ve momentum (easterly) zonal wind activity across the pole and manifest blocking tendencies at high latitude which adds further to NWP vicissitude...….. ...….Mitigation of HLB sustaining too long also probably aided by a weak El Nino forcing which acts to help the ITCZ further north in late Spring heading into early summer sooner than under low angular momentum La Nina conditions...... Forthcoming prospects? ….. assuming active tropical >extra tropical forcing sustaining angular momentum tendency through the greater part of May c/o weak El Nino circulation and aligned with w/QBO, increasingly inhibiting Atlantic and Greenland blocking heading towards the important seasonal wavelength setting as Spring turns towards Summer, then whilst such a pattern will inevitably sustain backwards and then forwards once more- its not unreasonable to hypothesise further re-setting of the Atlantic trough and downstream W/European ridge and re-cycling of increasingly warm patterns from an ever warming continent as the days keep growing longer. ---------------------------------------------------------------------- The most recent post following these extracts spoke of fine margins in respect of much of the wider discussions ongoing in these summaries. Categoric underestimation in that analysis, no doubt, of the vast amounts of vertical heat transfer generated into the pole by the recent Scandinavian height anomaly - - which has further augmented the final warming and thus created the "dynamic" response to the final seasonal warming of the stratosphere that has made the difference between a more conducive Branstator (mid latitude) ridging arrangement to late Spring warmth and the highly anomalous Greenland block verifying instead. The result being the polar vortex splitting and leaving a core cold element to our NE which is set to spoil the B/H weekend temperatures and increasingly also looking set to usher in a southerly tracking procession of lows from midweek. So one might assume such a reverse polarity outcome has also scrambled the polarity of the whole analysis, and left credible extrapolations of cool cyclonic conditions for weeks on end in its legacy instead? No, not really. The fundamentals remain that the seasonal stratosphere/troposphere transition might well be simply masking the direction of travel to an ultimate destination that sees transport of the end of season cold vortex back across the pole c/o the reverse polarity, helping to converge a mid term cyclonic mess in the process right over our heads, but with the Greenland height anomaly also fading and backing west towards Newfoundland and Canada with the result that something of a west based -NAO allows pressure to rise from the south and starts to draw up warmer air in the process. There are some hints of this in extended means, albeit the exact timing of this is open to question circa a few days bandwidth. Such an evolution would go full circle to re-setting the original analysis suggesting of an Atlantic trough and downstream ridge and return of something much more seasonal. As depicted by the sharply defined edged red anomaly in the Hovmollers plot below, this pattern evolution also draws on the significant westerly wind burst about to be set in motion in the West Pacific as the strong tropical CCKW related MJO wave propagates further east (and ultimately engages the standing wave at the Pacific dateline) - -and hopefully keeps a borderline Nino signal going into the start of summer and which assists in choreographing a rossby wave pattern suitable for downstream mid latitude ridge building (as the wildcard -ve easterly anomalies at higher latitudes fade out to summer transition of the stratosphere/troposphere state) As previously outlined, the importance of this is vast - because seasonal wavelength changes from Spring to Summer would lock in this type of default for periods during June, and possibly July in much the same ways as, by way of a few examples, during 1994, 1996 (to some degree) and 2006. Most of those years also had some Nino upstream forcing attached to them - and 2006 perhaps closest in this respect with an establishing and growing +QBO phase which helped supress sustained higher latitude blocks and facilitated low heights over the pole to follow the blocking of seasonal transition. The most recent post discussed some of the elements that could make things go wrong, and which also would encourage Atlantic blocking mechanisms to become the default instead - and which would persist or follow on from the upcoming unseasonal supressed jet stream conditions. So of course there is nothing inevitable about such repetition in 2019 However all three of the aforementioned years (1994, 1996 and 2006) saw highly underwhelming May's with a supressed jet stream and plethora of Atlantic/Greenland blocking prior to very good June and July's - but summer variants followed this in each case centred around extended dry very warm/hot settled spells and some spectacular thundery breakdowns and re-loads of the Atlantic trough and European ridge pattern. 1994 was especially notable for the thundery variant during both June and July.
  5. 29 points
    Can I be the first to welcome @knocker back to the asylum full time !
  6. 29 points
    Is mother nature trying to tell us NW cold lovers something?
  7. 25 points
    Greetings to you all! A glistening new thread for the month of May and early Summer! As we head deeper into Spring and into Summer (though I guess for some, May could be classed as a Summery month), a number of us hunt for warm weather with sunshine, thunderstorms and plumes. For some, you may be after some cool and wet, or cool and dry weather instead. That time of year where trees become thick of yellow, green and purple foliage, and flowers burst into life all over the place! A little glance at the models and you can see, using the GFS 18Z as example, that it's painting a chilly picture over the UK later this week with a cool flow developing from the North. This is thanks to High Pressure to the South-West of the UK linking up with the high heights over Greenland with a trough dropping down to our East from Scandinavia. But before that happens, a puny Low Pressure system to the West of Ireland, currently sandwhiched between both the High Pressure to our South West and the High Pressure over Greenland, will track South-Eastwards to join up with the Low Pressure to our East later this week. The Low will fill as it does so and become a wave feature. This helps out with High Pressure amplifying to our West in the Atlantic. That little cyclone will bring some showery rain over the UK today as it makes its journey South-Eastwards, with further rain and showers on Thursday. With regards to that Northerly following after (see charts below), the best of the driest conditions would most likely be over Western UK closest to that High Pressure. Chiller conditions likely further North and East you are with a chance of showers, possibly with some longer spells of rain and hill sleet and snow. Probably not much precipitation about, but some of the showers may have a wintry flavour to them. Most likely over Northern high ground and maybe to lower levels over Scotland. The 850 hPa temperatures the GFS shows below could certainly be cold enough to support some wintriness over Northern areas. Could be quite windy too, especially towards Northern and Eastern coastal districts. Did feel back in April that one or two of the chily outbreaks the models were showing would have been the last shot for the cold and snow enthusiasts. Nevertheless, this would very likely be the last chance to squeeze out some wintriness for the cold fans before next Winter. Their may also be enough room for the Northerly to back a little further West allowing lower heights from the East to become more influential and increase the instability for more widespread, potent, (wintry) showers. Equally, the Northerly may just get shoved further East with the High Pressure over Western UK giving the Scandinavian troughing a bit of a kick - more of the UK ends up staying dry and bright. There is a risk of some night time frosts later this week and into the weekend, which may cause some disruption to plant growth and farmers. Perhaps, though, nothing too servere and hopefully not much damage is caused. Still looks as though it would be a fairly dry period overall, particularly again over Western UK spots. Later on into the outlook, and it looks as though Low Pressure to the West of that Atlantic and Greenland ridging will try to take over. (Quite possibly with ridging over Southern UK hanging on): At 192 hours, the 18Z GFS, 12Z ECMWF and 12Z GEM generally show the UK under the Atlantic and Scandinavian's troughs spell! Some strong heights over Greenland maintained with Atlantic Lows directed over the UK. Could stay quite cool, especially over Northern UK areas, and maybe become more unsettled during this period next week. Since it is 192 hours away, things may still improve for those wanting to see more in the way of warm, settled, weather (including myself). However, it would be fair to say some rain is likely needed in some places still, considering how mostly dry its been for some parts, especially for the South East of the UK. Both the 6 to 10 day and the 8 to 14 day CPC/NOAA 500mb mean charts following similar ideas as the above operational runs with blocking continuing over Greenland and Low Pressure in the Atlantic. Perhaps some ridging influencing Southern areas of the UK at times (especially with the higher than average heights over Western Europe), so probably nothing majorly unsettled. Maybe a possibility some of the operational runs, such as that 12Z GEM, over-doing Low Pressure over the UK. https://www.cpc.ncep.noaa.gov/products/predictions/610day/500mb.php https://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php I suppose it will be interesting to see how the models continue to develop things. Wanna Be Good? Whatever happens, please keep things friendly and on topic in here. Some banter, including the odd bit of off-topic chat, is fine as longs it doesn't cause the thread to come off its tracks. The Netweather team will moderate this thread from time to time to keep it focused on the models and stamp-out inappropiate nonsense! Bad and rude behaviour will not be tolerated! Any issues with members, please use the Private Message system. Should you be naughty and disobey our rules, you may either get a warning, have your post removed or, if you've been very naughty, you may have your keys to the door of this thread taken away from you. Alternative Threads: To chat more generally about the Spring weather, please head over to the spring thread: https://www.netweather.tv/forum/topic/91223-spring-2019-moans-ramps-chat-etc/ The Summer one: https://www.netweather.tv/forum/topic/91676-summer-2019-moans-ramps-chat-etc/ And to post tweets about the models (although you're still welcome to use the Model Output Discussion thread), please see this thread: https://www.netweather.tv/forum/topic/87130-model-tweets/ For the Met Office outlooks, please use this one: https://www.netweather.tv/forum/topic/64157-meto-uk-further-outlook/ Model Output And Charts On Netweather: GFS GFS FV3 (Parallel) GEFS Ensembles ECMWF ECMWF EPS NetWx-SR (3km) NetWx-MR (9km) Met Office (UKMO) Fax GEM GFS Hourly Model Comparison Golbal Jetstream Stratosphere Previous thread: Thanks a lot all!
  8. 25 points
    Well that's me done on the cold and snow search for this year. Of course there's always the chance of a late March early April surprise but I wouldn't bank on it. The winter showed more promise than it ever delivered for many members on this forum. I count myself lucky to have had at least one very decent snowfall (10cms) which stuck around for about three days. Which is not to be sniffed at on the south coast of England. Hopefully next winter will bring something better to all my cold and snow loving fellow members. Until then enjoy spring and summer my friends and I,ll be back in the autumn. (Unless of course a snowy surprise turns up in the next six weeks lol.)
  9. 24 points
    This convectively coupled kelvin wave (CCKW) I have continued to reference over the last week or two has been of such strength heading through the Indian Ocean that it had much to do with the development of the devastating tropical cyclone Fari which sadly crippled the Indian state of Odisha in recent days. It has now passed eastwards through the Maritime continent through to the Western Pacific and in terms of the feedback processes from upwelling warming across the ENSO zones (see below tweet for illustration purposes|) has possible significant future implications to downstream patterns in terms of the ushering in of summer wavelengths - and when the dynamic response to the final warming of the stratosphere eventually starts to fade from influencing tropospheric responses. The bright red - intense white colours in the Hovmollers plot pick up the strength of the WWB heading through the W Pacific. On the VP200 anomaly chart depicting the CCKW tropical convection, notice the eastward progression of the CCKW in the first half of May to engage the dateline in the Pacific - and how suppression (yellow, orange. red colours) of convection appears in the wake of the tropical wave across the Indian Ocean and then Maritime continent respectively These westerly winds in the Equatorial Pacific propagating eastwards, tend to migrate poleward through the extra tropics with time, and programme swathes of downstream amplification. Where this amplification sets up is dependant on the longevity of the more transitional seasonal downwelled -ve easterly zonal winds across polar latitudes. The question is - how sustained are they likely to be? Any collapse in angular momentum caused by increase in easterly winds across the Pacific has the effect of transferring the amplification wavelength upstream to the Pacific and create a downstream ridge>trough>ridge trough response. The final ridge trough response being that in the Atlantic and European sector respectively. On that basis it could be seen that any Atlantic or Greenland blocking default created by a -ve ENSO atmospheric circulation feedback is a natural extension of any pre-seasonal higher latitude blocking such as we presently have. If the ocean/atmospheric standing wave is held back across the Western Hemisphere because of the effects that easterly trade winds have on supressing tropical convection in the Pacific - the consequential stable atmospheric environment is conducive to High pressure in the Pacific and a downstream blocking response also in the North Atlantic.. That is why the setting of a +ve ENSO wavelength in the Equatorial Pacific is useful for warm air advection patterns in our part of the Northern Hemisphere in summer because it encourages MJO related and associated separate induced cyclonic activity in that part of the tropics - which in turn helps promote a downstream Pacific trough/ridge pattern, and replicated Atlantic trough and downstream European ridge In this way, the CCKW is a very important event in reducing the risks of a more la Nina like atmospheric response generating sustained easterly trades winds heading into summer and also therefore less chance of any Atlantic blocking configuration to follow on from final warming HLB and then stick for any length of time. Ultimately, the current MJO wave will return, naturally as part of the "mini ENSO cycle" to the Western Hemisphere - note the suppression arrive in the Pacific as the signal returns from Africa back to the Indian Ocean in the last third of the month Based on the fact that the latest wave is already likely to adjust the Pacific SST pattern favourably, as detailed above, and help tip the balance more towards a summer ridge pattern downstream, then the return of the tropical wave pattern to the Indian Ocean later this month might well see a higher floor to the fall-back in angular momentum likely later this month - and that usually always occurs at the end of each MJO cycle. Currently globally averaged atmospheric angular momentum (GLAAM) is about +1SD above average which is a quite good place to be in ahead of the upcoming passage of WWB's associated with the CCKW. CFS and other model products are picking up on a possible further CCKW event heading into June. Its early to have high confidence in this, but its one to keep an eye on. . This watching brief then also ties in with what happens to the polar field pressure pattern in terms of the remnants of the final warming. Some current NWP extended products are hinting at wanting to try and retrogress the poleward amplifying sub tropical ridge that evolves through days 7 to 10 again and sustains the block to the north in the more extended period. This then potentially inviting another swathe of troughs to have the potential attrition to undercut from the west and promote further cool unsettled weather How credible is this? Assuming that longer term prospect chances have been improved by upstream tropical developments sustaining a supported angular momentum regime heading into summer, then the lifespan of dynamic fall-out from the final warming has limited sustainability heading into summer period, with a combination of seasonal wavelength changes, +ve momentum forcing from an El Nino type atmospheric feedback and assistance from the +QBO phase to also underpin this. So whilst a further round of attempted Greenland blocking cannot be ruled out in the medium term, then this might give way to a warmer mid latitude ridging pattern as Spring heads to early Summer. Though the sustained anticyclonic conditions of last summer seem less likely this year, and a potential thundery element exists which many would welcome on the basis of a reloading warm pattern and to add some interest to conditions. May 2007 was a generally +ve AO regime which gave way to higher latitude blocking through June and the rest is history. It was also a year where angular momentum collapsed heading into summer at the same time as an easterly -veQBO assisted downwelling of -ve zonal winds into the troposphere to align with weak sea ice and produce a very poor summer. The previous year, as documented in a post last week, had the opposite configuration with a higher latitude blocking in May followed by mid latitude heat ridges as soon as the calendar turned into June. This year the chances of more sustained relapse have not gone completely yet, and it will require a close watch on both the ongoing blocking patterns and angular momentum/tropical wave trends during the remainder of May heading into June - but latest events should have at least reduced the risks vs what was beginning to seem increasingly possible in recent weeks and create a better chance that this summer evolves closer to the better variety than the likes of 2007, 2011 and 2012. So that improvement from the south comes as suggested of late by the weekend to follow what looks a truly dismal week - albeit due to the persistence of the higher latitude blocking signal it looks now to set up initially further west than ideal to cut off the cooler air staying close by. However, the depth of cold air compared to this weekend is not there and liable to mixing out further with time. Its also not the end of the world if it morphs into attempting to retrogress with further fall of pressure undercutting it. It doesn't mean summer is destined to be over before it has begun. Such an evolution is far from certain anyway at this stage and some fine weather, albeit not a heatwave, still looks likely heading into the following week. But should this month continue to struggle to follow through on any recovery promise, the philosophy of ice in November and sludge and muck to follow comes to mind with its opposite counterpart in May. It remains the case that what follows afterwards matters much more in terms of hopefully disposing of the Greenland and higher latitude blocking..
  10. 23 points
    In view of the provocative game-playing (that I had gladly escaped during the winter) and the absurd quick fire reactionary responses attributed to NWP operational data, attendant with not enough attention instead to ensemble data (which in itself is simply only a snapshot of time in evolving patterns) its probably a good time for some more analysis. Signals after all lead models, models do not lead signals The seasonal demise of the polar vortex, amplified by tropospheric heat flux forcing as described in an earlier post, continues to dominate the NH pattern and inhibiting any late Spring build up of real warmth over the nearby continental landmass due to persistent feed of cold air advection from a displaced and rapidly dissipating area of leftover vortex broken away from the the eastern arctic into Scandinavia The persistent height rises to the north - a manifestation of the symmetry between the tropics and the pole and differentials between them which enhance tropical convection activity (MJO) and the resultant wave train in turn triggers equatorward flux in the Southern Hemisphere (i.e subsidence away from the Antarctic) and a +ve pressure signal (+AAO). At the same time in the Northern Hemisphere, the engagement of the eastward propagating tropical wave at the dateline teleconnects the opposite way to the SH with a -AO/-NAO - the latter attendant with upstream jet extension across Asia and the Pacific and greater flow into the southern stream. The Southern Oscillation (SOI) in response to the eastward propagating MJO signal has trended sharply negative in the past few days - an indication of -ve Outgoing Longwave Radiation anomalies ( OLR) and associated deep clouds and thunderstorm development close to the dateline - also as illustrated by the intense and sustained westerly wind burst continuing across the Pacific to the dateline https://www.longpaddock.qld.gov.au/soi/ As well anticipated in recent posts in advance of this WWB, angular momentum tendency, subject to 2 day lag, is significantly ramped upwards. The +ve AAM anomaly depicted around 30N in tally with the proxy data in the Pacific as depicted in previous plots The Global Wind Oscillation, a plot depiction of wind-flow additions and subtractions as supplied by frictional and mountain torques and other related mechanisms, has responded with a leap into high amplitude Phase 4 as these large amounts of westerly additions are supplied to the atmosphere. This is the kind of repeated GWO pattern which, with repeated westerly wind additions c/o tropical activity, would return the GWO to El Nino attractor phases 5 to 7, and would accord with seasonal wavelength changes and start to build further anomalous mid latitude ridges close to and just to our east during June (and possibly July) at the same time as height rises to our north start to fade out.. More on this uncertainty further below. So for this, and all the other repeated detailed reasons given in previous posts, it continues to be premature and pointless in equal measures to extrapolate assumptions of the resultant -AO led pattern into the early stages of summer (and in some cases evidently even beyond!). A lot could, and quite conceivably will happen over the coming few weeks at such a time of seasonal pivotal change. In the medium term, its worth watching the developing low heights towards Iberia and Biscay - these could play a role in providing a stark thermal temperature boundary between the cold air advection to the north and a much warmer humid circulation becoming ensconced around the low heights to the south and south west. How far north such a boundary might set up is uncertain at the moment, but some NWP is playing with this scenario in the extended period and its conceivable that another round of retrogression of the heights to the north could lead to a similar evolution to this week, but this time with less of the deeper upper cold air around to tap into further to the north and east and any warm air advection adjusted further east into Western Europe With that type of subtly adjusted wavelength evolution in mind, if (as discussed above) tropical convection patterns and angular momentum tendency can remain conducive, and this still isn't a given and needs to be watched for a while yet, then seasonal wavelength changes and gradual ascendency of the Hadley/ferrel cell heading into new month and new season change could flip a stubbornly (relatively) cooler pattern into something more sustainably warmer. Such as happened in some of the aforementioned summers in previous years that featured May's that seemed reluctant to embrace a substantive warm-up All that said, and returning to the opening theme above, some proper perspective is needed here - next week still looks to feature a much more pleasant spell of weather after this weeks anomalously below average temperatures, with some welcome sunshine that will lead to warm feeling days out of the breeze, especially in the north west and away from eastern coastal districts where low cloud could be a nuisance. In that respect not an unusual pattern for mid May and nothing untoward whatsoever to lead to writing off swathes of a season that is yet to begin and remains too uncertain to call (either way).
  11. 22 points
    Good morning gang, im going up the wood shed with me sausage sandwiches brown sauce .going to do what i did this time last year , so expect big changes in the charts later today ,ecm will show a stonking northern block at 192 hrs ,gfs later today will smell the Coffee ,met office will mention wide spread snowfall ,and the express will have 8 pages of Snow hell , jack daws are all flocking today ,squirrels are barricading their homes with straw ,help iv run out of prozack .I do like the ecm at 10 days , repeat 100 times , and here is the weather forecast , change expected soon ,cheers gang STellas all round .
  12. 21 points
    Last time I looked at a calendar, there were 22 days left in this month. I think anyone writing off the next three weeks on the basis that we have had a poor start to this month and then deducing the entire summer is a write off, probably needs to take a step back and consider their expectations. 2018 was extreme if you look at historical years with both the heat and the cold. We are not duplicating that this year so far for sure, but by the same token this also doesn't mean that we can confidently say that the next three months are going to be a copy of the last three days.
  13. 21 points
    I felt a sudden uncontrollable urge to say...BOOM..BOOM..BOOM..sincere apologies!
  14. 21 points
    Outlook - Trending towards a NW/SE split and very warm for a time The NH 500mb profile and surface analysis for midnight and the 0400 UK chart The low to the west of Scotland slowly drifts north east during today but bits and pieces of old occlusions will continue to bring heavy showers to N. Ireland and western Scotland, coalescing at times into longer spells of rain. At the other end of the country, in the south east, the current gloom will continue with further outbreaks of rain during the day courtesy of the old cold front still being a nuisance Elsewhere sunny intervals but perhaps the odd shower. Temps a little above average Tonight the low will continue to track north east to be west of Norway and the cold front in the south also finally clears. Thus a generally clearer and colder night, maybe just a touch of frost in places, and showers confined to the north west So a chilly start to tomorrow but then a fairly pleasant day for most with lighter winds, courtesy of a very transient ridge, but the nest frontal system approaching from the west with bring rain and strengthening winds to N. Ireland and western Scotland by 1400. And this will spread east and effect northern England and Wales through the afternoon. Temps still a tad above average It will continue wet and windy in the north through Tuesday night and Wednesday as the complex system tracks north of Scotland with the south of the country remaining dry. temps trending well above average. But to the west the oft mentioned deep low gas arrived on the scene and is 939mb in mid Atlantic Over Thursday and Friday amplification occurs with the Atlantic trough digging a fair way south and in the process initiating a long South westerly fetch into the UK and thus some very warm air So a very warm couple of days with max temps in the lap of the gods but certainly mid to high teens. Any rain rain confined to the far north west Wrong thread Will the string of garlic and the silver crucifix be sufficient?
  15. 21 points
    Ive been spat at and slapped...and kneeded-in the knackers..... Keep an eye on the annoms.. @500 geopt ht!.. Watch the divulge in evo..of height alignment with a STIFF-easterly flow.. And yes counterparted with notable isotherms!!!. Wear ya t'shirts...but keep a wooly hat; n jumper to wack over the top... @backloaded @winter strikes bk!! He whom laughs last...LAUGHS LOUDEST!! TA-LAR 4 NOW..
  16. 21 points
    I stepped aside of the winter season on this site for a variety of separate, but also rather inter related reasons - and the perennially occurring type of nit-picking discussion exchange on this page is just one of them. Nothing changes here - even if the UK maritime driven weather at a crossroads to a large continental landmass traditionally changes back and forth as always The reason I am exceptionally reappearing and responding to the latest sequence of misrepresentation and erroneous judgement from the posts in accord with the sentiments of alleged arrogance expressed above is because they blight not only the most busy winter period, but are demonstrated, smaller scale, a lack of respectful judgement and correct perception all year round. The original culprit most generally attributed to extreme over focus and expectation built around one preference bias solution according to the season present - that is bound to increase risk of error rate if all other probabilistic solutions, that my be present, are discounted. Such error rate leads inevitably to predictable disappointment, and equally predictable finger pointing and baseless unhelpful and judgemental blame game over the failure as part of the perennial ritual. Sadly the methodology (and methodologist) suffers the fate rather than the erroneous sky high bias expectation that feeds the negative reasctions Several things: 1) The diagnostic approach, commonly referred to as "background signals" is *supposed to be* a guide to help assess a pattern framework on a macro scale basis using intra seasonal timescales and feedbacks from recurrence factors existing within the tropics and extra tropics. These then invariably become dumbed down in acronym land as silver bullet snow-making mechanisms (in winter), hiding and invalidating the real efforts in attempting to learn and then reference their proper use 2) The reason that posts might start with statements such as "models are not picking up the signals" is not to brook arrogance and supremacy over computer software, or express the gift of a clairvoyant that other posters simply cannot possess - but as a means of matching a wind-flow (jet stream) diagnostic evident at any given time, to the "drawings" of numerical modelling and stating an interpretation of where NWP may evolve differently in future according to expected changes of wind-flow propagation from the tropics to extra tropics. It is therefore disrespectful and cynical to imply true motives of anyone styling their posts this way are disingenuous otherwise. - irrespective of the final outcome. 3) The diagnostic is extra complicated in the winter through consideration of the seasonal polar vortex - but the tropospheric wind-flow diagnostic remains an essentially valuable guide as to determining how the different levels of the atmosphere may behave, and whether they interact or assume a disconnected or overriding state. None more so than this season for example. 4) Clearly a very complex boundary area and formidable to attempt to dissect, and humans will continue to make mistakes and hopefully learn from those mistakes (if they are allowed the grace to) - but the advent of putting stratospheric research collected over some number of years into active practice on both an amateur and professional level showed it has been possible to make mainstream breakthrough in this aspect of science. Most importantly a degree of measured acceptance and respect.. That has proved inspiring to many, and many who have sought to attempt the challenges on sites such as this and others. Regardless of starting level of knowledge. Therefore equally, a tropospheric diagnostic that can help assess how conducive a hemisphere pattern *may be* to amplify through propagation of planetary waves (which may in turn impact the stratosphere in winter through the assistance of extra tropical mountain torque processes) is an invaluable complimentary guide next to stratospheric practice, to try to start disseminating its own processes. The "bottom upwards" approach within the atmosphere has also therefore started to become inspiring to many. in the same way as stratospheric research pushed boundaries. 5) However, the value of these diagnostics has to be to assess all probabilistic outcomes that may be evident, and so any post starting with "the models are not picking up the signals" is best attributed to the extent of all probabilities and not just the favoured bias solution. 6) It is certainly possible in the pursuit of humility to caveat posts with the disclaimer that more than just simply the bias solution is present (and I for one used to attempt to do this) but this clashes with the dichotomy apparent of where cold science meets weather enthusiast. Both have an obvious valid place. But on an internet forum there is never going to be a one size fits all answer to this and parochial attitudes relating to "background signals" will always exist on the one hand when the bias solution goes AWOL - and on the other hand intellectual snobbery will exist of those deemed allegedly trying to be too clever for their own good. 7) With all this mind, I don't see a duty of anyone to have to come back by order of proxy to explain where they went wrong, or why their allegedly "lofty" stance has ended in failure. I am sure most would wish to do this of their own volition, in the cause of positive explanation and assist to others as to what may have happened if and when the time was pertinent to do so . And last but not least as part of a process of learning from mistakes made themselves. But there is no contractual obligation to do so. I am sure all this does is serve to create wariness of ensuring they do not come back at all In conclusion I would suggest those who, commendably, persist still on these pages with the diagnostic approach, at any (or all) levels of the atmosphere are therefore between a rock and a hard place and will continue to not satisfy anyone as long as the true purpose of their posting is discredited and picked apart accordingly - through not pleasing the different ends of the reader spectrum. Minus a salary (in some cases) as just very ordinary "weather students" who are simply wanting to test their own curiosity.
  17. 20 points
    Howdy all! Just something worth pointing out - while not everyone is doing it, there has been a lot of GIFs and Memes used lately - particularly on page 27/28. Though I appreciate people are trying to add fun and humour to the thread, we would kindly ask if some of you would tone down your use of these funny animations and pictures, as it can distract from the main purpose of this thread. I know I must sound like a fun-stomper. But it’s just they’re kinda being overused now to be honest, and we may start removing some of them. Cheers guys!
  18. 20 points
    The first thing to remember is that estimating the surface temp from the 850mb is very rough and ready and is very often likely to be miles out. I don't know what you have read but it will be based on the lapse rate between the surface and 850mb. Air cools adiabatically as it rises, and the converse, and in the case of dry air that will be 9,8C/km and saturated around 5.0C/km. The environmental lapse rate is in between around 6.8C/Km So it is quite easy to calculate the surface temp, given the 850mb temp, if you assume the 850mb height as 1500m and a dry lapse rate. In the height of summer you can add two or three degrees for surface heating. But that assumes (a) dry air and (b) nothing interferes with the temperature structure between the surface and 850mb such as cloud, CAA and even subsidence and you could even include orographic features for any particular location .In practice this is very unlikely So the moral is... be wary
  19. 20 points
    Highly unlikely. Sustained Easterlies/North Easterlies (3-4 days plus in duration) in Winter across the UK are rare. Once every 5/6 years maybe (on average)? Many on here need to grasp some basic UK weather realities ahead of next Winter (and future Winters), instead of being sucked in by a few internet 'heroes' saying "It's coming" or "the models are wrong".
  20. 20 points
    Did you manage to get to work?
  21. 20 points
    I really can't understand some of the negative comments on this thread, yet again this morning. Ok, so the Old GFS, not great. But the GFS (Para), shows this and actually they're not a million miles, apart!! 00z ECM at t240, continuing on from last night's 12z run. Core of heights surging N.E., towards Scandinavia. Signs of trough disruption, out to our S.W. I certainly wouldn't describe these runs, as dreadful/hideous. A little OTT, I think!! Regards, Tom.
  22. 19 points
    What a run that was! Whatever the temps turn-out to be (25-28C will do me) a fundamental pattern-change looks more like occurring, as time goes on...Of course, it is only a model? Anyone else see something rude?
  23. 19 points
    It is indeed proving to be the case that the models have been over progressive with the eastward intrusion of the trough - too far east (and for too long) General NWP culpability evident - but just as illustration here is the ECM ensemble change even over 24 hrs representing the early part of next week @Singularityhas nicely described the tropical>extra tropical forcing in the mix which is behind some of the NWP erraticism and which also encompasses my own suggestions in the wider post (of which the selected extract above comes from) re CCKW/MJO progression that might cause the models to find something of a reverse gear on the processes of extending the trough too far east into and across the UK. The downstream ridging proving more resilient than the modelling suggesting. The other part of the equation is the seasonal transition within the stratosphere from its winter default vortex position to its summer state. This is bound to increase -ve momentum (easterly) zonal wind activity across the pole and manifest blocking tendencies at high latitude which adds further to NWP vicissitude. This cross section of the atmosphere layers clearly shows the stratospheric/tropospheric evolutionary story since the SSW of January and the equatorial flux of AAM anomalies which resulted in sub tropical and mid latitude blocking (including the spectacular late Feb "heatwave") rather than the expected high latitude cold block coming courtesy of poleward momentum of +AAM anomalies - usually seen under conditions of active MJO tropical convection propagating towards, and then through the Pacific. To follow this immediate post SSW period, the return of zonal westerlies and re-organisation of the polar vortex apparent as per the blue anomaly representation through the layers of the atmosphere during March. In turn, now leading to the relatively late final warming of the stratosphere which is also complicating the models handling of tropospheric placement of these blocks . This interaction of seasonal downwelling from the arctic with influence of maladjusted angular momentum related wind-flow patterns at mid latitude, is proving to reduce the amount of Pacific amplification that has been expected by NWP - and in turn the amount of downstream polar jet flow extending the fragmenting and decaying end of season vortex and resulting trough out of Canada and US across the Atlantic. Furthermore, and to complicate matters further, the trend of equatorial zonal winds related to the Quasi Biennial Oscillation (QBO) are slowly increasing westerly in the new +ve phase. This suggests at least at face value that effects of any "dynamic" tropospheric fall-out from final warming (easterly zonal wind anomalies) of the stratosphere into the troposphere should be mitigated, relatively supressed and shorter lived - despite the late break-up (certainly later than last year c/o Feb SSW 2018). QBO Calculated at NOAA/ESRL PSD 30mb zonal wind at the equator, zonal average For info https://www.esrl.noaa.gov/psd/data/climateindices/list/ 2018: -19.02 -19.37 -19.77 -21.41 -24.23 -28.45 -29.10 -20.41 -9.91 -2.79 3.36 + 8.05 2019: +9.02 +9.25 +11.82 (Jan, Feb and March figures) Mitigation of HLB sustaining too long also probably aided by a weak El Nino forcing which acts to help the ITCZ further north in late Spring heading into early summer sooner than under low angular momentum La Nina conditions. If we take a look at where globally averaged angular momentum is at what is looking like the bottom of the "lull" in the tropical>extra tropical wind-flow cycle, then there is scope for quite a pre-summer rally to boost prospects for warm spells in this run-up period. Still a little above average at this time, having lost the momentum peak of late winter Forthcoming prospects? As tropical forcing progresses eastwards through the tropics and westerly wind inertia builds in response, this increases +ve frictional torque tendency at the inception point where these westerlies add momentum to the atmosphere - starting the process of angular momentum tendency rising once more. Notice the red anomalies (westerly winds) progressing towards the Western Pacific as the easterly inertia (blue shading) ahead of the tropical wave is scrubbed out with time Another way of looking at the wind anomaly progression across the tropics is through the VP200 convectional anomaly chart - the convectional suppression (yellow and orange shadings) presently over the Pacific gradually being eroded by the advancing -ve convection anomalies heading from the Eastern Indian Ocean through the Maritimes and towards the West Pacific (equal to MJO Phases 3,4,5-6 on deterministic model MJO plots) These eastward progressing westerlies added to the atmosphere circulation from the tropics register a response from the Global Wind Oscillation (a phase depiction of wind-flow pattern additions and subtractions) and result in orbit from falling angular momentum Phase 8 to rising angular momentum Phase 4. This likely is a prelude to the GWO fully engaging the El Nino attractor phases 5,6 and 7 once more in the further outlook as the Nino standing wave in the Pacific is re-engaged during May and hence why in my opinion NWP is starting to advertise a ridge response once more rather than sustaining the trough On this basis, assuming active tropical >extra tropical forcing sustaining angular momentum tendency through the greater part of May c/o weak El Nino circulation and aligned with w/QBO, increasingly inhibiting Atlantic and Greenland blocking heading towards the important seasonal wavelength setting as Spring turns towards Summer, then whilst such a pattern will inevitably sustain backwards and then forwards once more- its not unreasonable to hypothesise further re-setting of the Atlantic trough and downstream W/European ridge and re-cycling of increasingly warm patterns from an ever warming continent as the days keep growing longer. In the shorter medium days 5 to 10 period, its a case of seeing how the models resolve the ridge placement now that the ejected trough is backed west into the Atlantic. This will determine how much cooler air advection comes south before the suggested higher heights close to Greenland fade in the longer term and hopefully set up a mid latitude ridge as day 10 ensemble means are trying to converge on. To copy paste the last line of the quoted post however : "A case though of keep watching to check this evolution stays constant and seeing how NWP responds"
  24. 19 points
    Looking towards the spring equinox the Gfs 00z operational becomes very spring-like with high pressure and a southerly breeze with temperatures into the mid teens celsius range..perhaps upper teens c in places!
  25. 18 points
    Hello Mike - this cross section of the layers of the atmosphere clearly illustrates the downwelling process of that final warming - quite the contrast to the +AO dominated close to winter and first half of Spring. I think that puts a perspective on this Spring and its mixed character. Aside from the anomalously very cool start to May which is concordant with the switch to -AO c/o the dynamic nature of the final warming, the CET means for March and April are fully contemporaneous with that earlier generally +AO profile - both months comfortably above average. So the capricious surface conditions of the season have rather masked the fact that this Spring as a whole (so far) has not been quite as poor as some might try to make out. Also the highly anomalous warmth of the second half of Spring 2018 is a distracting and distorting comparison perspective - even in this warming world and increasing occurrences of noteworthy temperature anomalies breaking frequent records, consecutive late Spring and Summer seasons of such homogenous warmth still represent an upper benchmark. This is the UK after all and not a sub tropical climate as much as it is not a cold continental one in winter. Expectations and preference ideals are too often asymmetric with geographical latitudinal realities Looking ahead, and striving to build on previous analysis - some further thoughts to add extra substance. There are signs a more coherent +ve PDO pattern might try to set up with come modest relative cooling in the West Pacific - and by comparison, warmth consolidating in the eastern Pacific. This accords with El Nino standing wave signature being assisted by the eastward propagation of convectively coupled kelvin wave (CCKW) MJO envelope. As such, it accords with MJO Phase 8 imprint and downstream rossby wave train amplification of the wavelength Furthermore, this contradicts the identity of Springs heading into summer like 2007,2010, 2011 and 2012 where a -ve PDO was part of either an imminent La Nina (2007 and 2010) or a long established La Nina (2011) or an even more established Nina struggling to transition to ENSO neutral (2012) If we take the globally averaged angular momentum budget, the characteristic low angular momentum state (as manifested by -ve PDO tendency) is clearly choreographed during the Springs of both 2011 and 2012 Quite different to 2019 A w/QBO prevailed as is the case this year in 2011 - however the Pacific feedback was very different and clearly much more La Nina-like than this year - and the characteristic mid Atlantic ridge and downstream UK trough increasingly played a hand as summer was arriving and seasonal wavelengths changed. Furthermore, the QBO phase does not accord with the very easterly state in Spring/Summer 2012 where some other background parameters were closer to this year than 2011. The strong e/QBO overrode any attempts made by the atmosphere to try to become less La Nina-esque during early summer 2012 and sustained blocking at the "wrong" latitude instead.. Calculated at NOAA/ESRL PSD 30mb zonal wind at the equator, zonal average For info https://www.esrl.noaa.gov/psd/data/climateindices/list/ 2012 -16.07 -15.25 -16.74 -17.62 -22.04 -25.89 -27.82 -27.93 -26.60 -24.51 -18.95 -10.02 2013 -6.07 -1.23 2.85 8.39 12.64 13.38 14.27 14.66 13.12 11.69 12.45 12.55 2014 13.13 12.68 11.72 7.15 -2.81 -13.98 -19.29 -21.64 -23.24 -23.86 -23.65 -25.38 2015 -26.70 -28.62 -28.15 -24.38 -12.33 2.18 7.45 10.97 12.07 13.38 12.79 11.39 2016 9.34 6.77 3.16 0.64 2.37 3.86 6.25 10.07 10.48 12.83 14.16 15.09 2017 14.92 14.78 14.35 13.88 8.01 -3.18 -10.48 -14.42 -15.28 -16.79 -17.20 -18.12 2018 -19.02 -19.37 -19.77 -21.41 -24.23 -28.45 -29.10 -20.41 -9.91 -2.79 3.36 8.05 2019 9.02 9.25 11.82 13.36 - (April update) Strengthening westerly phase evident. A +ve (westerly) QBO, in tandem with an El Nino forcing on the atmosphere is a more "hostile environment" for any final warming feedback to prevail than occurred in 2012 and failed as a result of too much La Nina -ve PDO forcing in 2011. Summer 2006 is that excellent w/QBO and El Nino combination example, previously referenced, where HLB in May gave away to anomalous warm mid latitude blocking early in June. In respect of the CCKW as a noteworthy event, it will be interesting to see seasonal model updates in terms of ENSO SST predictions as benchmark for how Nino might prevail. -May is often a key month here.. Should El Nino rally once more, with the standing wave engaged in the Pacific and the atmosphere reflect a coupled feedback loop with the extra tropical GWO starting to repeat orbits returned back to the Nino attractor phases, then portents are good for summer. Different to last year in respect of the likelihood of no persistent ridge for weeks on end and the Atlantic trough and downstream ridge breaking down and re-setting and allowing thundery breakdowns, and then cooler changeable interludes leading to re-set of the default warm pattern. That is not a forecast - but its quite typically traditional weak summer El Nino. There is little danger of the southern stream getting too strong as it did in the start of the "super Nino" of summer of 2015 - its more a case of avoiding increased trade winds breaking down the Nino-like trough/ridge pattern and creating a more persistent downstream trough instead. Especially because this years final warming has had a "dynamic" element to it, with considerable poleward heat flux drawn into the final warming and further amplifying the downwelling -ve zonal winds to the troposphere/stratosphere boundary. This might serve to give it that little extra resistance to the natural effects of seasonal wavelength changes and advancement of the ferrel cell in the tropics as assisted by the favourable effects of wQBO usually creating an elevated tropopause due to westerly shear in the lower stratosphere. But there are signs as previously discussed the odds are stacking against such resistance and whilst, as we know, the seasonal models like UKMET et al are not bullet proof - such general analysis as attempted here does provide some logical resonance and credence to such predictions of a warm summer pattern Time as always will tell - but much more will continue, as ever, to be gained from comparing progress of ensemble NWP suites in reading all these signals than wasting time trying to draw too many observations and conclusions from the smorgasbord of unicorns offered by intra day multi faceted operational output.at long distances All the computer models have their inbuilt biases, but the GFS continues to often display a -ve tendency (low angular momentum) response to its interpretation of tropical signal imprint on the synoptic pattern - particularly as the MJO completes its cycle and returns to the Western Hemisphere onwards to the Indian Ocean. Such timing as due later this month and where differences of modelling are already apparent with the ECM .So some further erratic output and disagreement could crop up as the coming week progresses in terms of the extended period. Good reasons therefore to particularly not overreact to operational data and also be cautious with ensemble suites and compare their progress over 2/3 days rather than 1-1..
  26. 18 points
    ECM T240 out now, and there is a reason I've been posting NH charts recently, would only normally do in winter, the very strong final warming of the stratosphere is important here, we need to see this wane, and is doing. ECM T240: No ridging into Greenland, and a ridge coming our way...start of summer...
  27. 18 points
    Calling it a day! Towell has been thrown No lasting cold 850s in view again and have been trying to hang in there, still believing since the big bust in January! Was giving it till Sunday but calling it now, hoping as I write this something may still show soon but my faith in model analysis has been broken. Sad seeing the beeb showing the bfte last year this morning. Siberia! Unreal graphics on forecasts. Red warnings, (m74) closed. I was on route to Scotland the day after. Made it but couldn't see anything bar the poles on the a66.☺ Enough reminiscing. See u for the thunderstorms during the heat or December for another 47 hunt. Thanks to you all for your posts. Good and bad. Hot and cold.
  28. 18 points
    Spring may well be approaching but the ensembles are trending back to winter! After what could be record February warmth I wouldn’t mind a bit of March snowfall
  29. 17 points
    I've been watching like a hawk for any signs that the Atlantic trough will behave more Nino-like and resist becoming negatively tilted with the blocking high being able to build to the northwest of the UK as a result. The 12z GFS and to a lesser extent ECM runs have finally brought that and have also thrown in a shift north with greater link to the Canadian trough for good measure, but it's just one set, with no preceding trend. So I can only hope that they're onto something; I want to see signs that the Nino base state is establishing itself better while we wait for the final warming fallout to fully subside. If they are on the right track, then we do at least see a more eastern position to the Arctic blocking focus become the most probable compared to a Greenland-Canada one. This provides the opportunity for the far south to see some useful rain (which it's been missing out on lately) without having to contend with low temperatures; troughs to the south are better able to drive warm air across the UK from the eastern Med. That being said - I have a sneaking suspicion that the models are generally being a bit too 'clean' with the Arctic blocking, with the actual result keeping the main focus of the blocking high further from the pole. A tendency to overdo those Euro troughs at the 5+ day range may also play into that.
  30. 17 points
    Some longer term musings from me tonight. My position coming into spring (my 'prior' in Bayesian speak) was that summer would be decent and hot one, but less settled overall than last year (see previous posts I think around early April), with more thundery breakdowns. How are things looking now? On no account can it be argued that the latter half of Spring is similar to last year! I think some of that can be put down to the late and exceptionally strong final warming in the stratosphere, which has resulted in the kind of high latitude blocking that those of a cold persuasion crave in the winter, this year without result. But that should dissipate, and if it does where does it leave us? Long range model output over the last few months has favoured high pressure domination in the region of the UK, although as far as I can see with more variability as to precise location re the UK (see my post yesterday on latest CFS runs). Sea surface temperatures are interesting, the current ones conducive to N Europe high pressure: Compare mid April last year and mid June last year: Clearly in April SST subdued near the UK after the Beast From the East, by June that's all gone after the hot second half of Spring last year. We haven't had that this year, so we could end up in a similar place by mid June, close to UK, but we need to watch the heat from Azores to UK, very strong last year, a signal there this year but weaker at the moment. The cold water south of Greenland is present in all plots though - some continuity there. So there may be some similarities with model output, SSTs going into summer, also atmospheric angular momentum (AAM) generally above average looks likely (see recent post by @Tamara ). Todays models, here GFS, FV3, GEM and ECM on NH view at T240: Whilst the blocking is to the north, the models are not suggesting a rampant Greenland high. Remember last year, in May the driest warmest weather was in the NW, only translating to the heatwave further south in mid June. Different so far, but is the journey into summer 2019 about to join a similar track to 2018, but a month or a bit more down the line. Will be interesting to see!
  31. 17 points
    Hi Knocker, you’re always welcome to post in here! Try not let anyone get under your skin (or whatever it is that is causing problems). Best to ignore any posts you may not be happy with, including ignoring/reporting any members that are being a nuisance, or you can always chat to us! Some people maybe getting a little bit over excited by some of the charts this evening - which, in a way, is understandable as I guess some of us are eager for some hotter weather. Some of the charts are likely being over-hyped too. There’s no total guarantee that some of those charts, especially the ECMWF ones, will come off like that. Charts a week(ish) away can always be liable to changes. I suppose though, the general pattern seems to be establishing to see some build of pressure next week. While I don’t want to force you to use this thread, your posts are appreciated by a lot of people (your morning summaries, for example, are really handy) and you provide balance and level-headedness with your content. (That’s not to say everyone else on here are biased with their posts, but you definitely one of the members that provides value to the Model thread )
  32. 17 points
    Starting to get interesting I see - these adjustments in the Sunday ridge position put me in mind of how we've seen many advertised cold easterly incursions become adjusted east or southeast of us. The plume creeping closer to us for early-mid next week shows the mark of the exceptional WWB that Tamara included in her excellent roundup yesterday. Top-drawer WWBs drive top-drawer amplification of weather patterns. We've been fearing further cool winds from the ENE but it seems the Atlantic trough might just about have a positive enough tilt (well, non-negative is what matters here) that the surge of warm air is due north then east of north, which then invigorates the polar jet to the north of the UK: ...keeping the HP cell from heading to our NW or N and so setting up a prolonged plume event for the UK. Remains to be seen how much the surface flow orientation will favour us , mind! While the 850s look very impressive over SW UK especially, surface temps don't look that way. While GFS' maximum temp predictions are probably showing some of the usual low bias that we see during spring-early summer events involving very warm airmasses arriving via a brisk flow, it's likely not to be by as much as some may think, as the surface flow is still from east of the plume on Tue and still a bit east of the main thrust of it on Wed. Further on, it appears that the Nino-like theme of reloading plumes punctuated by thundery breakdowns is becoming the GFS favourite. I'm a little wary, though, of just how much it lowers heights across the Arctic all of a sudden. It'd be a lucky break for UK warmth (or heat) - seekers though!
  33. 17 points
    Christ alive, its the UK not death valley. We'll have months and months of rain to endure from late July until next May. Chill.
  34. 17 points
    Hi James - a thoughtful summary and deserves a response I think in the context of seasonal wavelength changes in addition to the transition period of the stratosphere to its "summer" position there is bound to be flips in patterns when wind-flow patterns undergo sequences of retractions and then forward momentum once more as we have been seeing this Spring - and is quite common to see in many Springs, notwithstanding the unprecedented changes in climate that inevitably will amplify and/or distort responses. But the physical responses of changes in wind-flow patterns and the torque mechanisms that drive these changes remain constant nonetheless and continue to play an important role in attempting to decipher pattern changes. In that respect its another reminder that its not the ENSO base state per se that matters in terms of direct correlation, but the relationship that the atmosphere adopts to it in terms of weather pattern adjustments (in tandem with all the factors between the seasonal changes between tropical and polar stratospheres and also of course how the seasons impact sea ice at such pivotal times of switch. What of those wind-flows? We can see from the Hovmollers plot that since the first few days of the month we have seen a drop in a long period of westerly wind bursts across the Western Pacific towards the dateline, as part of a response to tropical convection patterns having finally weakened through March following a very long active period since November. With an imminent trade wind burst in the Eastern Pacific as can be seen shaded blue on the plot this represents a peaking of something of a "lull" phase in this Nino phase - which is not unusual in any ENSO cycle. The effect of greater easterly trade wind inertia or reduction of Nino westerly's c/o eastward progressing tropical convection is to create a deceleration of wind-flows upstream in the Pacific and a consequential fall in angular momentum tendency Initially this serves to weaken the Jetstream heading downstream across the Atlantic, and hence has helped to promote and preserve the downstream ridge across Scandinavia, but as at the same time as the lobes of polar vortex start fragmenting in response to approach of final warming of the stratosphere, then breakaway troughs appear such as programmed next week to disrupt from Greenland to close to the west of the UK. Meantime the downstream ridge is preserved to the east and north and east as the negatively tilted trough process gets underway as modelled. The response of the Global Wind Oscillation, which is a plot depiction of these changes of wind-flow, is to head towards Phase 8, as reflection of falling angular momentum tendency of at least temporary loss of surfeit Nino westerly wind inertia in the global atmosphere. This gradual orbit from the Nino phase 7 represents the first part of the jet retraction process of recent days with the blocked Scandinavian High. The second part of the process is the trough splitting the ridging pattern as the amplifying Bermuda High hoovers up our ridging to the west and allows pressure to drop in its place. There are indications from the modelling that this retrogressive process c/o decelerating tropospheric and stratospheric zonal winds might complete with a further backing west of the trough and pressure rising from the SE to follow the more unsettled phase starting from the end of the Easter weekend. This needs to be watched to see how it might unfold for the extended period in ensemble products in the next few days
  35. 17 points
  36. 17 points
    Morning all, So, a big pattern change is on the way, as the blocking area of high pressure over Europe the last 7 days slips south to allow Atlantic lows and frontal systems in from the west across the UK from tomorrow. The change comes as the jet stream, which has diverted well to the north of the UK over the past week, shifts south, strengthens and takes aim at the UK over coming days. The strengthening of the jet stream is likely linked to an upper ridge pushing north across Alaska and the arctic before dropping down across NW Canada, kicking out very cold air here and northern Canada southwards across central and eastern US later this week and into next week. This will in turn cause a steepening thermal gradient across NE USA and out across NW Atlantic strengthening the jet stream across the North Atlantic. Over the weekend, the models forecast an increasingly disturbed spell, as the developmental left exit of a strong jet streak (where there is strong divergence aloft and convergence at the surface) moves toward the UK/Ireland and will likely to allow rapid cyclogenesis to take place over the Atlantic with a deepening low pressure system headed towards NW UK for Saturday, though GFS, UKMO and EC differ on depth, EC has more of a wave, GFS and UKMO a deeper closed low passing Scotland. Another low looks to develop in a trough in the jet which looks to move further south across southern Britain for later on Sunday, this could deepen as it approaches the UK too. Potential for a named low if one these lows deepens sufficiently to produce severe gales. Then the models suggest unsettled cool to sometimes cold zonality next week, as the jet stream shifts south of the UK, the depth of cold of the polar maritime westerly flow differing between 00z GFS and EC, sub -5C 850mb temps spreading east a lot further south than EC, which keeps the sub -5C air generally over northern UK. So question marks over how far south any wintry precipitation can develop, so would hold off getting too excited for snow away from northern hills. Even the colder GFS shows little in the way of wintriness away from hills in the north and west, though some low-level snow possible in the far north. But, with air pollution levels rather high today bringing poor air quality to much of England, Wales and southern Scotland, thanks to high pressure inversion and lack of wind, it may perhaps be some relief to get some clean Atlantic air blowing in by the weekend! Though the unseasonably warm sunshine will probably be missed and unlikely to return for a while.
  37. 17 points
    ECM looks wintry at day 9-10 with a slightly undercutty scenario- also a dusting over the uk @day 6
  38. 17 points
    Outlook - Warm, very warm for a time, and relatively dry but tending towards a NW/SE split The NH 500mb profile and surface analysis for midnight and the Chatham, Cape Cod, sounding for same time just to show the measured 190kt jet over the eastern US There is currently still a fair bit of rain around over the north west as the waving cold front continues to move slowly south east, and this will persist through the morning but slowly fragment on it's travels as it reaches Wales and the Midlands by late afternoon. Another mild day but cloudy for most apart from the south where there will be sunny intervals. The front will slowly clear most areas overnight but still generally cloudy with bits and bobs of rain/drizzle around, mainly in western regions. Another frost free night except perhaps for northeast Scotland where is clearer. On Thursday we are in the pattern that has been discussed previously so will skip any repetition and suffice it to say becoming dry and warmer with perhaps some cloud and patchy drizzle in western parts early on Overnight Thursday through Friday a similar, very warm and dry, day but the complex upper trough to the west is taking slightly closer order and some rain may effect the north west from a surface cold front. Another very warm day on Saturday, these temps are not written in stone, but we now have twin cyclones to the west and the trailing cold front from the initial one, now near Iceland, may bring some rain to the far west late on. As the two cyclones adjust positions overnight Saturday through Sunday the weakening cold front will finally traverse the country so cloudy with sunny intervals and maybe just a tad cooler
  39. 17 points
    Sorry but i told you so isn't an attractive trait. You took a punt on mild and the coin dropped right for you this time. Maybe you should call the meto and tell them to ditch their 100m super computer for your gut?
  40. 16 points
    The May GloSea5 output has been published today, so here are a few charts for the June-August period. Bottom line first, here are the tertile probability charts for 2m temperature and precipitation: Strong signal for above average temperatures, and no real signal for precipitation. I think this is consistent with a largely settled summer, punctuated with thundery breakdowns. To the extremes then with the outer quintiles plots for 2m temperature and 500mb heights: The hottest category is much more likely than climatology and is an increased signal over last months output. The heights plot shows less than 5% chance of the lowest category, should be the last nail in the coffin for those who are predicting a 2007/2012 redux!
  41. 16 points
    A new version of the v8 radar is going to be available soon (initially as a beta product) to Extra subscribers. We've been hard at work with a variety of additions and improvements, including: Fullscreen radar option Improved controls Upgraded precipitation type display with improved detection and additional precipitation types Virtual weather stations Upgraded weather station overlays Rain and snow notifications (optional) Upgraded future-radar Upgraded lightning display Multiple postcode markers and zooms Some screenshots of a few of the features - they are from earlier versions so will have changes/updates in the beta. New weather station overlays: Virtual weather stations, on radar display of a station (you can setup multiple locations) Your stations will also store historic data which you can view: We hope to have the beta version available shortly
  42. 16 points
    Gorgeous end to ECM this evening!! Yes please!!
  43. 16 points
    Eagle eyes obviously present... Based on yesterdays assessment those day 10 means reflect good cross model continuity for re-set of Atlantic trough and downstream ridge and warmer air to approach from the south. Taking account of the caveats that could still alter this evolution for all the detailed reasoning also given yesterday and recently, it still pays to do some QC on NWP assessment in terms of latest suite consensus (at the very least) before reacting However, the next few weeks continue to advertise a significant westerly wind burst propagating east through the West Pacific to the dateline and providing a timely shot to keep an atmospheric Nino feedback going into early summer. We are not quite there yet, but Its worth keep repeating that this is increasing the chances of warm plume scenarios rather than cool and changeable North Atlantic flow around a mid Atlantic ridge and downstream trough response
  44. 16 points
    Outlook - Due to become colder by the end of the week but the weekend should be sunny for most with light winds. After that still a tad uncertain with the energy flows jockeying for position. The percentage play is for the Atlantic trough to win on points. The 300mb wind field at midday Monday illustrates this quite well The 500mb NH profile and the Atlantic surface analysis for midnight and the 0300 UTC UK chart A clear start to the day in the east and N. Ireland and this will remain the case pretty much during the day, albeit clouding over somewhat. But the cold front that is causing patchy rain in western regions at the moment will move slowly east with the patchy rain becoming increasingly showery. during the afternoon a trough will bring more showers to N. Ireland. The temp spread reflects all of this with the south east becoming quite pleasant The showers will peter out through the evening and overnight but will continue a while in northern Scotland and the south east of England. So generally a clear night with the odd fog patch by morning. But note the trough over Scandinavia is getting organised and the associated cold front is on the way south. Thursday will be a day of sunshine and heavy showers but the cold front is now tracking down Scotland so a belt of more persistent rain here and colder air in it's wake Over Thursday night and through Friday the cold front stalls across the country as the subtropical high amplifies in the west so essentially a cold day with frequent heavy showers, The cold front clears the south coast during Friday night as the ridge moves east resulting in Saturday being a sunny day with temps a tad below average after a frosty start, Not feeling that bad in the very light winds. But showers will still effect eastern coastal regions as troughs track down the North Sea in the northerly flow by Sunday we are getting to the tricky time, After a widespread frost a generally sunny day with temps still a tad below average but still possible showers in eastern regions. And another cold front is on it's way south and is just north of Scotland On Monday the gfs has the front tracking down the country some some rain and showers around with temps still a tad below average
  45. 16 points
    I've mentioned this before - people are unduly worried about this. The UK's reservoirs are at generally high levels across most of the UK. (some regional exceptions) Put that into context - we had one of the driest summers on record last year and there were little issues. The media fans peoples fears and there's no need. We'll be OK. We can enjoy a nice summer... Read the UK reports here: https://www.gov.uk/government/publications/water-situation-local-area-reports Even Kent and South London is at close to full which is arguably one of the driest parts of the country: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/794178/Water_Situation_Report_Kent_South_London_March_2019.pdf Honestly - no need to worry.
  46. 16 points
    Right folks after a think im calling time on this cold search, it's been fun while it lasted. I don't feel the need to have to keep coming on here and explaining to certain posters why I post 10 day charts and how much of a waste of time it is. I sincerely respect every poster on here including the mods etc. I for one will never come on here to ridicule any poster who posts far fetched weather charts and information, as far as I'm concerned they do it because they enjoy it and they are entitled to their opinions. It's been a blast folk, even though things didn't go to plan... Well for me anyway!! So I wish you all a fantastic and healthy summer and hopefully I will be back in November for another long haul in finding the winter that many, myself included have craved for so long. Thanks folks. Kind regards
  47. 16 points
  48. 16 points
    Depends on what you are seeking from a cold spell. Chances of powdery snow, ice days, many days of lying snow is becoming increasingly unlikely, although remains possible to early March. However a snow event which may slowly thaw the next day is possible for the next 6 weeks. After such a dreadful winter I would be happy with the latter.
  49. 16 points
    Got to disagree a bit with that. This winter without doubt has been a fail - but not just for teleconnections. It was a fail for the model forecasting industry too, most especially in our neck of the woods for the UKMO....and I suspect you dont see them as teleconnective forecasters. Your reading of "overarching authority" I would take as a theory of where the signals appear to be taking us. This is not certainty - it is a reading of signals. Those who take them as certainty are either irritated by the attempt in the first place (though I've never been able to work out why anyone would be irritated with another person's attempt to make sense of a very complex process and put out a forecast on a weather site) or have no faith in our ability to try and make sense of the process....and this is usually very strongly flagged by those posters being the ones who choose never to make an attempt at a forecast at more than about 10 days' range. I have absolutely no problem with that - there is a lot of sense in sticking to what can be reasonably seen as falling within a window of reasonable model accuracy, but where I do have an issue is when those characters then choose to pour cold water on the attempts of others to make sense of the longer term.....particularly given that the critic tends to stay within the conservative window of accuracy and then pour scorn on those who are trying to work further ahead. That's just bad from every angle - humanity would have made next to no process throughout history if progress were left to those with that kind of mindset. "Extenuating circumstance"? - is that just code for another unforeseen factor? Surely it must be....and by its very definition that falls, once again, within the envelope of reading signals. Not sure what point you are trying to make here other than suggesting that teleconnective forecasting ignores the bits that disagree with the "theory" - whatever theory for a season that might be. No - certainly dont agree with that. All signals are valid and I'm sure we are going to learn a lot from this season. Furtado put out an excellent tweet over the weekend on exactly this topic. Test and observe. Isnt that science? And "if revisited at all" - you are just being negative here. You know very well there have been papers produced over the last 20 years on a range of forecasting developments, from solar impacts to vortex disruption - and all of these were seen as fringe science prior to investigation. I remember being on weather forums when low solar impacts were chuckled at by serious posters....and then peer reviewed literature silenced them. The same to an extent has happened with vortex disruption - and now we are wrestling with developments in our understanding of ozone circulation, different types of split, QBO phase etc etc. None of these are factors that are not revisited. Quite the opposite. You are right that certainty is limited. But I'd rather push the boundaries of that limitation rather than not even try.
  50. 16 points
    I hope not......that would be 16th June
This leaderboard is set to London/GMT+01:00
  • Newsletter

    Want to keep up to date with all our latest news and information?

    Sign Up
×
×
  • Create New...