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Showing content with the highest reputation on 10/12/17 in all areas

  1. 43 points
    Thanks Broadmayne Blizzard This isn't, or shouldn't be an ego platform, and I think its a good idea myself to appreciate the good thoughts and contributions of a very wide breadth of posters on this forum, and not focus on select contributors. Much as BB62/63 outlined so well yesterday evening Furthermore, as keeps being repeated but equally keeps getting ignored by a few members, its a good idea to represent correctly what posters say, in the correct perspective and context and not put a misleading slant on them, however un-intentional, in most cases at least, that may be. It takes enough time to put posts together, let alone having to keep re-correct words that often get put in the mouth Last week, advice was given not to get too sucked into ups and downs of intra day and ensemble suites and take them at face value. The summaries of bluearmy and MWB read between the lines very well and seem quite appropriate to range of possibilities over the medium terms. But, at present, from evidence that is available and up to date, the Global Wind Oscillation is heading to Phase 8 and the December composite is reflected pretty well in the upcoming weeks synoptics, and within a reliable time period I think beyond this time, is where extra care is particularly required in terms of NWP suggested output. Models are going to be very sensitive to the natural ebb in the tropical cycle and climatology will play a part in bias to a longer sustaining westerly pattern in these circumstances - especially set against a highly disorganised stratospheric profile But there has continued to show a willingness for tropical convection patterns to mirror the definitively east based nature of this La Nina - and hence display synoptic traits that are quite different to the predictable increased vortex intensification and flatter pattern that I happily admit I approached this season with a plenty of caution The evolution back to Phase GWO 4 (where we have just been), crucially assisted by seasonal wavelength cycle changes the pattern heading towards and especially into January. Nothing is ever guaranteed and no-one can be wholly psychic with the complexities of weather science. But that composite isn't too different to the anomaly chart that is still clearly in NWP running in ba's post this morning. Best not get hung up on translating that to a precise surface pattern or take the timing too literally, (though Christmas would be nice obviously in an ideal world). The downside pattern in terms of Indian Ocean tropical convection patterns taking over is the flatter pattern risk, emphasised in each and every post. But on the basis of the above analysis, the point to continue to labour is not to get pushed and pulled reactively by each and every model output suite I'm very much anticipating some atmospheric and angular momentum budget updates which will give some further important clues as to the extended Pacific and Atlantic patterns, and also developments beyond that in terms of looking NE. I'm sure others are very much doing the same By the way, its snowed in the last couple of days around the UK, away from the far south, and is snowing as I type outside folks windows at the moment and so please get out in it, take lots of pics and enjoy it whilst it lasts! Today illustrates what a microcosm one region of the country can be, let alone differences across the country commonly seen themselves. I'll trade the very underwhelming autumnal charade being played out here at the moment for putting some faith in a change of angle of approach and hopefully improve my own fortunes in joining in with some fun before too much more time has passed
  2. 33 points
    WINTER 2017/18 REPORT No. 4a WITH DECEMBER 10th INPUT PART 1: With my main weekly reports tending to be quite long, I shall continue to split them into at least 2 parts probably posted several days apart. This one will be in 3 parts. As they can take many hours to prepare, this will enable me to draw more on the most recent model runs rather than earlier ones. Part 2 will include an update of my European indicators and analysis and part 3 will focus on my Arctic indicators. A REVIEW OF THE MODEL OUTPUT OVER THE LAST FEW DAYS AND A LOOK FURTHER AHEAD I am writing this from a rainy and very windy Exmouth (currently 8 am) but I am keeping one eye on the radar and following the areas receiving the snow. Good luck to those that get (or have already had) a decent fall and enjoy it while it lasts. At least it gives me an opportunity to concentrate on this report! With the snow occupying so many regular posters with many of them on the specialist regional threads, there has been a real lack of activity on this thread with little analysis of the model output going beyond the next few days. So, I thought that I would spend a little more time today looking at this compared to my usual approach Well that was another extraordinary and very exciting week for model watching. Having struggled to nail down the detail regarding the northerly that arrived during Thursday behind storm Caroline the models then encountered the complex pattern concerning the slider low. There was reasonable agreement on the timing and the formation zone but variations in the trajectory. Although on a macro scale these were very small differences, they were highly significant in terms of our tiny island. The track varied from model to model and run to run right up until 12 hours out but they all showed a generally east-south-easterly to south-easterly direction. Around 5 days out, the range of tracks were mostly between north Northern Ireland exiting around the Humber estuary and central Ireland exiting around the Thames estuary or north Kent. A few varied north and south of these limits. Then the trend was slightly further south and back again. All this fluffing about would not normally get so much attention but the final track would determine who gets snow (and how much), who gets rain and who gets nothing out of the ordinary. With so many snow starved members on this forum, emotions began to run very high. If computer models were given an emotion chip they would probably laugh at our behaviour! Turning to the broader picture and looking ahead we are in the middle of some very interesting pattern changes and the models have been struggling with the next week and beyond. It looks like most of the next 7 to10 days will be rather cold to cold but not quite as cold as the last couple of days. The milder wedge that encroached into the south-west overnight and today is being squeezed out and moving away south-eastwards. Most models now show another slightly less potent northerly later this week and, yet again, more or less coinciding with another weekend. There will be some sharp frosts wherever it clears overnight, particularly over the snowfields. Some more wintry precipitation looks quite likely but also some snow melt as well. The day to day detail will vary and really needs to be studied in the T+24 toT+60 range. This is not meant to be an attempt at a detailed medium range weather forecast, I’m just setting the scene for the following week where there is once again some considerable uncertainty with the models showing some diverse evolutions. Broadly, the background signals suggest (as explained in several excellent posts by the likes of @Tamara, @Glacier Point and several others) that we “may” briefly see the PNA turning negative with somewhat reduced amplification over the Atlantic with a flatter pattern for a few days(or slightly longer) and the PV reasserting itself to some extent. Then, the indications are that we shall see the PNA going strongly positive again with renewed strong amplification in the mid-Atlantic and into the Arctic with the PV thoroughly disrupted again and unable to take up its usual position and strength for this time of the year. There are also signs that the MJO may come to life again later this month just as it’s moving towards its important phases 7, 8 and 1 which often assist with HLB patterns. “Should” these changes transpire, we are likely to see some very blocked patterns again with the jet stream buckling, meandering, possibly splitting with the southern arm quite likely to be stronger and more dominant and probably taking a route well south of the UK. If we stay on the cold side of the jet, this might lead to further northerlies but there are some tentative but strengthening indications that we might see a strong build of pressure to our north-east. This might lead to a Scandinavian HP and even a build of pressure from Siberia and Russia pushing westwards. If this set up really takes hold, then a true “cut-off” Greenland HP is not out of the question at times and even linking up with the Scandinavian HP at times. There are also signs of stratospheric warmings later this month – not a full scale SSW shown yet but this may assist in prolonging the cold spell well into January. Remember that GP and Tamara both said that the models are highly likely to struggle with this possible pattern change and the timing of the changes is particularly uncertain. Some of the output has been quite progressive by hinting at a build of pressure towards our north-east from as early as day 10. Other runs have shown the changes around or just after Christmas (including yesterday’s MetO 15 to 30 day outlook) and this would be right at the end of the GFS and GEFS runs. So we must be really patient and not be overly concerned with any run showing a 10 day period of much milder and more zonal weather in the run up to the Christmas holidays (I know that as the model output changes from run to run so will the mood with some posters producing their usual agony to ecstasy and back again comments!). It’s extremely rare to see a prolonged cold spell lasting for weeks on end and even most of our severest winters had at least one milder interlude with December 2010 and December 1981/ January 1982 being prime examples. In fact during my lifetime (1953 vintage) only 1962/63 saw very longs periods of ice days with just the briefest of slightly less cold weather (although the south-west did see a few short-lived milder periods). CAUTION: Before anyone gets too excited about this, the renewed blocking is by no means certain and a flatter more zonal pattern with a much stronger PV may still prevail later on. The temporary change to a flatter pattern next week might gather momentum and last for an extended period. There is no point in me or anyone else having hunches about the forthcoming broad scale pattern changes and we need to take stock and follow the updates from our teleconnection specialists. Remember it’s these signals that drive the models NOT the other way around. Let’s just say that there seems to be some great “potential” for something much more memorable in terms of cold spells for this winter. We’ve got off to an excellent start and there are still 80 days of meteorological winter remaining! We can begin by having a closer look at some of the longer term output. I rarely comment on the model runs much beyond the 7 to 10 day period. What I want to show here is the range of possible evolutions. I will not do one of my cross model analysis in this report (perhaps I’ll do that comparison in a week’s time). I will not show the jet stream or temperatures and I will not even use the usually slightly more reliable model(s). I will use the GEFS and look at some of the perturbations and examine some of the outcomes shown. The 6z output has been rolling out for a while (it’s now 1200). GEFS 6z RUN ANALYSIS FROM DECEMBER 10TH: The current chart T+0 Moving on I have selected the T+144 and T+384 charts as well as the halfway point at T+240. a) The control run: T+144 T+240 T+384 I really do not understand all the worry. The control run is one of the warmest towards the end and finishes with HP just to our south and a fairly week westerly flow. The most important feature is the PNA returning towards neutral and showing signs of going positive. Out of the 20 perturbations there are none which are really negative and only 5 which are close to neutral with the other 15 either positive or very positive again. Many show HP somewhere over the Arctic with some maintaining it right over the pole. About 6 have HP over or close to the UK. Some have LP close to the UK but often to our north or north-west (not dissimilar to the patterns we have seen recently with quite frequent northerlies). The most common feature is that the vast majority of perturbations show HP somewhere over Europe, Scandinavia of Russia, with some showing some very strong cells and ridges. b) The Mean: T+144 T+240 T+384 The mean chart can be a little misleading as it averages out some of the more extreme variants. The main thing to notice is the PNA going positive again with higher pressure extending across the pole from Alaska to Siberia. The weakish looking LP centred around Greenland masks a few perturbations showing much deeper LP in that region and many showing higher pressure near there. b) Perturbation 4: T+144 T+240 T+384 b) Perturbation 7: T+144 T+240 T+384 b) Perturbation 8: T+144 T+240 T+384 b) Perturbation 12: T+144 T+240 T+384 So if you run through all these charts, you'll see that I deliberately selected those which show quite a variation in the final outcome but my main point stands and even the charts which show LP close to the UK still show "mostly" colder than average patterns. Currently, following the milder period in week 2 (possible lasting from 7 to 10 days or so), the longer term indications are very encouraging for "coldies" and very much in line to what GP and Tamara have hinted at. Finally, I'll be back within a day or two with part 2 of this report with a close look at European temperatures and what we might expect from a possible easterly later on.
  3. 24 points
    Could you explain what is 'interesting' to some new members that chart just looks like a kid has drawn on it with crayons
  4. 24 points
    Five clusters on the extended eps tells me that the modelling is waiting to decide where it's going also, it's just over two weeks since we saw this mid Atlantic/greeny high and nw euro low anomoly raise some eyebrows in here this morning we have this chart for Xmas - not a bad place to be methinks as it won't be exactly like this and adjustments in coldies favour could be very festive indeed
  5. 19 points
    You know the weather has turned into something serious when the model discussion thread has vanished in importance behind the regional threads When was the last time we had a start to winter like this? Anyway, a week of pretty cold uppers showing across the board now. Beyond that, the scatter is HUGE so I'm not too worried about the 6z operational at this stage.
  6. 15 points
    Snowline has moved back across the water now so north kent / Surrey etc back in the fray - great wrap around as well heavy snow here in Eltham -1cm , wifey just text 0.2c in NAG with heavy snow as well - settling on top of the earlier snow as temps only got to 0.8c because we lived in Greenhithe today was the first day my 3 year old saw snow !
  7. 15 points
    Must be a snow event if you can hear a pin drop in here right now! Anyway, Tomorrow night could spark some interest once again for people in SW or Southern England. Some undercutting cold air could bring some snowfall from that approaching storm from Northern France. Some strong winds yet again with this system, especially so for the Far SE coastal regions. ECM is a little more keen on the low being further North. After then, enjoy the snowfall as a brief (becoming v.brief with every run) mild intrusion likely on Wednesday, and then back to a colder Northerly setup. Rinse and repeat basically. And then there's the current conditions in the strat... What a winter this could turn out to be and its only December 10th!
  8. 15 points
    Very quiet in here which often happens when some snow is imminent for certain areas . This slider low must surely go down in NW history as one of the most microscopically analysed , with every jog south or north by a few miles met with panic or joy ! Putting aside this current saga which is drawing to a close we have seen some interesting trends over the last day on both the ECM and GFS trying to develop a ridge near Scandi towards day ten. Looking at the De Bilt ensembles we’re beginning to see a small cluster developing some very cold conditions. There are hints upstream that we could see a bit more amplitude developing after a relaxation of the positive PNA. This would help as it will begin to pull back the PV and send a bit more energy se which you need to develop lower heights over Southern Europe to support any high. It might be that we might need more than one attempt to get that Scandi high but perhaps it might arrive a bit sooner if the models are still slow at picking up the correct MJO signal . Singularity a few pages back made an excellent post regarding that and it does seem that the models forecasts were wrong and weakening the signal. So after an initial suggestion that things might turn milder it’s possible we could see the mainly cold weather extended .
  9. 14 points
  10. 12 points
    Im in the milf sector too, I guess it has its benefits
  11. 12 points
    MORNING GANG ,i have not posted much lately ,recently lost my lovely wife of 38 yrs married .Up till about 10 minutes ago i was sat watching the pouring rain and watching the trees swirl in the wind ,hoping that it would turn to heavy snow HEY PRESTO its arrived , now this is much earlier than i expected . pretty heavy now ,for those who say it wont pitch i have seen many a snow fall pitch on wet ground over the years , no guarantee though .Radar looking impressive to our north and if the precipitation can carry on for several hours we could see a winter wonderland , great reading all your reports on this forum ,the snow currently is coming down in waves but likely that once the colder air takes a hold proper ,and gets rid of the warmer air just a little above our heads we could see i guess a good prolonged fall ,cheers all LEGRITTER .
  12. 12 points
    Good news for the s / se..Latest information shows an increasing risk of some snow across London and other parts of the southeast today and overnight compared to yesterdays models plus an increasing chance of wet snow across the southeast tomorrow with temps a little colder than yesterday's models were showing..good luck with the snow! Looking at the week ahead, tomorrow and tuesday looks cold with frosts, ice and snow in places..the midweek period becomes less cold with some rain but then later in the week cold air returns from the north with widespread frosts and ice risk returning. The Gfs 00z then shows a strongly anticyclonic outlook with crisp sunny days and very frosty nights with freezing fog & further ice days, especially where fog persists or is slow to clear!
  13. 11 points
  14. 11 points
    Because as Tamara and GP pointed out the other day there will be a transition period from the end of the current Atlantic ridge driven cold spell to another cold spell come xmas/new year driven by hieght rises to our north and northeast. This was always on the cards and it is no surprise to see it in the modelling.
  15. 10 points
  16. 10 points
    Big forecast bust for the GFS here high res hirlam & aperge spot on- !! Another 20-30 mile slide overnight brings heavy snow to london --
  17. 9 points
  18. 9 points
    What's really interesting today is that the model data has done a great job for 99% of the time in terms of prec type, with the prec in the SE, it has it turning inrceasingly wintry from 1400, so the radar will start to change more at that point. One thing we've looked at, and may start doing for the radar is running the modelling for the prectype in 15 minute increments rather than hourly, then changes will come through earlier in situations such as this.
  19. 9 points
    To the folks saying no gritters are out...Just think about it. Each local authority has thousands of km of roads, and a handful of gritters. The chances of you actually spotting one unless you are stood there for 3 or 4 hours in the same spot are pretty small The gritters were out. Grit isn't a magic pixie dust that stops snow from settling.
  20. 8 points
    In Bournemouth 23c but at least we have the sea all is not lost.
  21. 8 points
    A quick look at last nights NOAA, GEFS and EPS anomalies, not forgetting previous runs, to see whether there are any indications of the forthcoming evolution. I need to keep the waffle short as I'm on my Tablet as my main website connection is still on the blink. Overy the next 14 days there are some upstream changes perhaps indicative of the PNA going negative. An Aleutian trough develops with a stronger Alaskan ridge and more importantly a reorientation of the Canadian vortex lobe and associated troughs, one of which is aligned east south of Greenland. Quite importantly this affects the orientation and intensity of the Atlantic Ridge and with a strong upper flow still leaving the eastern seaboard a tendency for the flow over the Atlantic to become more zonal Having said that the flow in the eastern Atlantic does abate somewhat and splits under the influence of the aforementioned Atlantic Ridge, positive anomalies NW of Norway connected to the east European Ridge and the weakening trough to the south East of the UK. Ergo the changeable and quite cool weather could quite possible become more settled with Temps creeping up to be near average but more than likely a return to the proverbial north south split.
  22. 7 points
    Re the Scandi HP, there is definitely signals for a strong Scandi block, several methods suggest it. What isn’t clear is the infkuence it will have on us. Wrong orientation or too far east and nothing, then the other option. I too am not buying the brutal flat outlook in FI charts, I think we’ll lose a touch of amplification along the way but next weekend’s Atlantic Ridge still very much on in my books. Beyond .....it is FI. BFTP
  23. 7 points
    We've got 4" of snow already, and judging by the radar, it's going to keep coming for hours and hours!! I am restored!!!
  24. 7 points
    Trying to fall back to sleep with a lamp post outside your window is the hardest thing ever
  25. 7 points
    Hi guys... (just about) Snowing lots of smallish flakes, settling easily. Temp -0.5C,Dew Point -2.4C Winds fairly light.ESE. All looks good for snow to last at least until midday according to the BBC News weather just seen. To me it looks like last nights forecast. Good to see it is sticking everywhere. I think we are all going to get something and in some areas it may become very heavy as it pivots. I expect most people to get about 10cms -some areas will get more. I see we already have 25 people on board - you lot are idiots. My wife told me!!! MIA
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