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  1. 7 points
    Tbh mate, its been doing that all summer and so far has failed to deliver......
  2. 7 points
    In the context of discussions in recent days about El Nino, AAM and anomalous amplified troughs and ridges then looking back at my posts attempting to document progress through the summer I think this one was quite pivotal. https://forum.netweather.tv/topic/83255-model-output-discussion-1st-june-2015-12z/?view=findpost&p=3221175 The Atlantic sector pattern at this time suggested to go the favourable route for the continental heat courtesy of ridging over Europe to extend over greater parts of the UK. What happened as we know was different. The reasoning is quite straightforward when broken down into simple English. It also should help illustrate why there is never any direct 100% correlation between macro ocean/atmosphere states and resultant synoptic patterns. It furthermore illustrates another good reason why the Global Wind Oscillation is such a useful guide in terms of interpreting where and when these variations may occur Lastly, but perhaps more importantly, such tools as valuable as they are, will always give very good guidance to macro patterns but cannot provide specific micro detail forecasts for the UK (as one very small fragment of the NH) and for that matter other boundary fringe areas where the jet stream, next to a large ocean such as the Atlantic will always determine those precise specifics in terms of placement of pressure systems - and dictate the consequential fortunes of whether one is north, south or directly under the Jetstream. This complex scenario conundrum fully epitomises a summer like 2015 for the UK and the position it holds at a geographical crossroads for weather types. The UK has been the precise crossroads of fortunes for Europe as a whole this season. It was (relatively) more straightforward in the Spring with a decoupled atmospheric negative GWO/AAM state to the El Nino ocean state which kept the UK and much of Europe homogenously cool. But the second half of June into the start of July saw what had been coming for some time - decisive coupling of the atmosphere to the ocean state through intense tropical convective forcing through the Pacific and a breakthrough in upwards tendency in AAM after months in a depressed La Nina-esque state. This breakthrough state however was more potent than envisaged - and involved a record MJO Phase 7 amplification with deep convection imprint on the atmosphere in the passage of the convective wave through the Pacific. It was actually too much of a of a good thing for the UK because although it assisted blocking, it has, largely, put the blocking in the wrong place (for warm and dry summer weather fans) This is where the relevance of eastward and northward propagating Rossby wave influence lies, as talked about in previous posts, in determining large scale global patterns which subsequently transcend the macro pattern to the more micro one - depending, globally, often where tropical convection is based around the ring of tropics. In very simplistic terms (it is more complex than this!) for the purposes of the Atlantic sector, and Europe (but most especially the UK next to a large ocean) the further west the tropical convection forcing is based, the less poleward momentum transport there is to our closer higher latitudes. In very crude terms to keep it (very) simple, for summer fortunes a position based around the maritimes is most beneficial for wave activity to pump up anticyclones from the sub tropics to mid latitudes (i.e ridging from the Azores edged east to influence the UK and NW Europe). However, stronger tropical convection forcing further east through the Pacific, with the MJO into Phase 7/8 will see augmented Rossby wave activity to higher latitudes in our sector. This raises pressure over the pole (hence the predominant -AO profile through the heart of this summer) and also upstream increases the sub tropical jet stream with the result that ridging downstream in the Atlantic sector is supressed and flattened and the main downstream warm/hot anticylonic amplification occurs further downstream over central/eastern Europe So there is not necessarily any one size fits all synoptic pattern to any given ENSO state, let alone El Nino. We also have to take into account seasonal wavelengths - and these can be provided through the guidance of GWO composites (adjusted to the appropriate 3 seasonal months) http://www.atmos.albany.edu/student/nschiral/research/gwo/composites/JFM/hgt500_1.png The upper air anomaly charts will give good appropriate guidance for the short medium terms, but they will be influenced increasingly by the direction of travel of the greater atmospheric circulation pattern - and this is where the GWO can be especially helpful +AAM is associated with westerly wind bursts across the tropics and sub tropics which are very characteristic of an El Nino coupled ocean/atmospheric circulation regime. However, regional area variations over oceans and continents will affect how synoptic patterns distribute themselves over much wider areas further away from the original forcing source. Essentially the stone and ripple effect on the pond It has been an active season for Pacific storms this summer. Such Pacific storms involve the creation of strong frictional stress signals and are superimposed onto existing AAM signals as determined by the background flow. So, strong eastward and northward propagation of wave activity from the tropical convective forcing boundary, which pumps up anticyclones at determined latitudes, and augment troughs at others, are further complicated by the net frictional "sink" source of more 'local' Typhoon activity and also are part of overall GLAMM budget (beyond just the westerly wind transport momentum of the atmosphere) in line with the Pacific El Nino state. The combined effects of these large scale frictional effects on the AAM budget are very likely linked with jet stream signals at upper tropopause level, but they also must be connected with the lower boundary where extreme torques act to either remove or add AAM. The basic principle of constant flux and Mother Nature not allowing a vacuum clearly underlined here. These are basic principles of AAM - and thus also must be principles of basic physics So, a lot of combined ocean forcing in play which affects the overall AAM budget and the trajectory of the jet stream upstream from us. But frictional torques have land based effects as well in the form of Mountain torques. Jet streams plough into high mountain ranges and provide another source of Rossby wave activity that affects the jet stream ribbon and also part determines the placement of troughs and ridges around the globe. The GWO orbited amplified Phase 4/5 in late June in response to the MJO picking up forcing amplitude significantly through from the Maritimes onwards through the Pacific. The response to this was mid latitude wave activity momentum transport that created the Sceuro ridge and the hot plume at the end of June/early July. Phase 4 into 5 signifies the engagement of an + East Asian Mountain Torque (EAMT) , . What happened thereafter is that the MJO continued to gain amplitude onward through the Pacific and this increased wave activity in our sector further poleward and created heights to our north (with the AO taking a dive accordingly). At the same time, the effect upstream of the Asian torque was to accelerate the Pacific Jetstream downstream from it, further accelerating the rossby wave action of poleward higher latitude AAM transport (to increase arctic blocking) and add strength to the sub tropical jet stream across the US and downstream to our Atlantic sector. The Global Wind Oscillation reflecting this by moving from Phase 5/6 through high amplitude Phase 7/8 as we went through July. The flattened pattern through active STJ and amplified heights to our north pushed the end June/early July mid latitude hot ridge amplification south and east into Europe. This manifested in the cooler and more widespreadly changeable pattern of the second half of July - more especially the last week. So to try and put all this recent synoptic history together, +AAM is favourable for blocking patterns per se as we can see through the poleward rossby wave action it brings. But from documenting the events of July what we also can see is that the degree of amplification and wave activity, and where the subsequent amplification(s) occur which will determine who, and where, is affected by the troughs and ridges - and which side of the jet stream they lie on. In our case, a strong westerly jet in summer with blocking in the wrong place (for summer) over the pole is not going to assist the advection of heat to our south - with the main ridge kept too far away from us to our east and south. The argument therefore is that El Nino can be best for very amplified MJO spikes in the Pacific in winter - when heights to the north and a southerly tracking jet stream are much more popular for obvious reasons. On the other side of the coin, tropical convection forcing too far the other side of the globe over the Indian Ocean will assist the development of tropical ridges northwards - but it will also serve to retrogress those ridges well to our west so that we are on the 'cool' side of mid latitude anticyclones with a propensity for troughs to drop into the space (the UK especially) A typical -AAM type synoptic chart from the Spring - with the retracted Azores High and the strong upper Canadian trough flooding the Atlantic with cool air http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2015052800-0-6.png. Somewhere ' in between' could be simplistically argued best to get the right amount of poleward propagation to inflate anticyclones in the 'right place for warmth in summer - i.e over or just to the east of the UK and NW Europe - but not too much poleward AAM so that (in summer) the heights occur over the pole instead, depress the Jetstream and flatten the pattern. These descriptions have been deliberately over simplified for purposes of explanation. There is, as ever, more to it than this and we can look towards the effects on rossby wave activity through the tropical zone wind QBO phase state (we are transitioning from -QBO to +QBO) as well as the obvious effects on jet stream amplification through arctic sea patterns and subdued solar forcings - but the large scale atmospheric circulation, as described, is plenty reason in itself for the divided boundary that has been the UK this summer - between the heat to the SE of the UK and the cooler moist atlantic to our west and NW. Looking ahead - current NWP modelling suggests the upper trough linking into Europe and eroding the heat is a replica response to the GWO re-tracing Phases 7/8/0. http://www.atmos.albany.edu/student/nschiral/research/gwo/gfsgwo_1.png However, with MJO forcing much more repressed in the Pacific than July, returning westwards at low amplitude, and not expected to play much significant part synoptically - then a further widespread longer lasting breakdown beyond the current warmer more settled spell such as seen in July is less likely. http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ECMF_phase_51m_small.gif http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/NCPE_phase_21m_small.gif Some attempts at raising heights over the pole again, but neutral/positive AO mainly prevailing. A further SE/NW spilt probably re-commencing with the base ocean/atmosphere state keeping control. With this in mind, worth again also taking into account GEFS -AMM tropical forcing forecast bias. This re-spin cycle probably seeing out the summer. Those in Europe shouldn't expect any pause in their remarkable heat wave to last especially long. At the other end of the scale, more potential cool and changeable/unsettled frustration to the NW. But that is beyond the coming week which although still features rain/showers somewhere in the UK on various days, should also provide something better for most at some time
  3. 6 points
    The MJO is currently hanging around at relatively low amplitude in phase 6... the placement is very good for warmth to occur this time of year (based on the composites at http://www.americanwx.com/raleighwx/MJO/MJO.html), and although the amplitude is low, we are seeing suggestions in the model output of high pressure to our E/NE which does tie in nicely with the phase 6 composite for amplitudes greater than 1.0: Incidentally phase 7 in July has a similar appearance, as does phase 8 in June. Shifting by 1 phase each month... coincidence? Anyway, it will be interesting to see how soon the MJO leaves its current state, as it's spent the past 24 hours drifting in the opposite direction to what the models predicted would be the case. If it lingers for much longer, we could perhaps see high pressure to our E/NE proving increasingly stubborn in the model output. Shorter term, we already have a lot of uncertainty to contend with thanks to the anticipated low pressure over NW Europe. For example, while GFS has the system pushing in late Wednesday and crossing England on Friday, UKMO delays the arrival by at least one day and then moves it to our SE on Saturday, managing to do little more than introduce some instability to the atmosphere overhead. This by and large looks to be a consequence of low pressure near Iceland being held back further west by UKMO, the difference notable as early as Thursday. Having said that, GFS' 00z operational run had the low in a similar place to UKMO's 12z, yet the European low still pushed north(east) sooner. Perhaps it simply reflects differences in the model physics. In such situations, we often see GFS and GEM in one camp and ECM and UKMO in the other. The GEM 12z operational is similar to GFS so that's half of the equation in place... let's see what ECM comes up with later this evening. Considering the GEFS ensembles with respect to the GFS and UKMO operational runs, the spread of outcomes (see below - showing the range of 500mb heights across the ensemble suite) regarding the European low is not particularly large on Friday, just about encompassing the UKMO operational along with the GFS. By Saturday it has become much, much larger... unusually so for less than a week ahead. Clearly the advance of the Atlantic trough is a long way from sorted out: By the way, if I could do with explaining anything in my posts further, please don't hesitate to ask - I'm still getting used to sharing my analysis in this way
  4. 5 points
    The troughing into Western Europe and well into the med is a big change. the ECM op first to pick up on the drive of lower heights in a se direction from the Atlantic trough. it's been a hot dry 8 weeks in Iberia and the western med. all change!
  5. 4 points
    The GEFS 12z mean shows increasing Azores high influence for most of the UK looking beyond the week ahead which I think is good news.
  6. 3 points
    CONVECTIVE / STORM OUTLOOK MONDAY 10TH AUGUST Valid: 10/08/2015 00z to 11/08/2015 00z Synopsis A broad cyclonic southwesterly flow covers NW Europe on Monday, with a southwesterly jet stream crossing the UK. A waving cold front lies SW to NE from Devon to roughly The Wash at noon, before the front moves east to clear Kent around midnight. Further west, shortwave upper trough and occlusion moves east across Ireland and then northern UK during the afternoon. ... IRELAND, N. IRELAND, SCOTLAND ... Sharpening shortwave upper trough, visible on WV imagery over the Atlantic west of Ireland Sunday evening, will cross the above areas during Monday ... steepening lapse rates and creating forcing for ascent which will support heavy showers or thunderstorms. 40-50 knts of deep-layer shear and strong SWly upper flow will promote storm organisation with a risk of hail, gusty winds and intense downpours leading to localised flooding. There is a small chance of funnel clouds or even brief weak tornadoes forming in stronger storm updrafts, particularly as surface winds back ahead of approaching shortwave increasing low-level shear. ... WALES, S ENGLAND, MIDLANDS, N and E ENGLAND ... Further south, a warm and humid airmass characterised by theta-w values of 16C will become increasingly unstable as dry air incursion associated with the SWly jet over-runs this moisture-rich airmass combined with forcing for ascent increasing with falling heights and lift along waving frontal zone. So embedded convection is likely in the rainfall spreading NE along the frontal zone with a risk of torrential downpours accompanied by isolated thunder across the above areas. Localised flooding will be the main threat along the frontal zone. Risk of thunder will initially be across SW England/Wales in the morning, before transferring towards N and E England in the afternoon.
  7. 3 points
    We don't need KL or M.I.A we have NSIDC """sea ice extent places 2015 now at around 4th highest in terms of daily extent, below 2014, 2013, and 2010. However, sea surface temperatures just north of the ice edge were 0.5 to 1 degree Celsius (1 to 2 degrees Fahrenheit) cooler than average, raising the potential for rapid ice growth through the remainder of the winter season"" http://nsidc.org/arcticseaicenews/
  8. 3 points
    your getting it mixed up with a new law that comes into effect next april the 1st ,no wearing of hats or driving gloves and no chewing chewing gum when overtaking .
  9. 3 points
    I just want to point out a difference between Antarctic and Arctic sea ice, but without taking the ENSO thread further off topic. Hopefully here is ok. The seasonal cycle in Antarctica is much larger than the Arctic, with area climbing to around 15 million km2 in their winter, and dropping to around 2 million km2 in their summer. So the ice is essentially recycled each each year. On the other hand, the Arctic used to grow to about 14 million km2 and drop to around 5 million km2. Part of the reason was that the Arctic sea ice was was much thicker on average with much of it capable of lasting through the summer despite warmer temperatures and being surrounded by warm land. The Arctic basin is quite closed off, so ice there could end up decades old, growing thicker and more resilient to melt. Now, part of the reason that the Antarctic sea ice has grown in the last few years is due to an increase in the circumpolar westerlies, which pushes the sea ice away from the continent and spreading it out. It's obviously cold enough that the ice blown out into the southern ocean is quickly replaced with a fresh thin layer during their winter, and so actual ice coverage increase. In the Arctic, we had a spell of strong +ve AO phases from the 80s until the late 90s. Many researchers believed that this increased export of Arctic sea ice further south at the time. But in the Arctic, this means transport of the old, thick, resilient ice south and out of the Arctic, only to be replaced by thin, new ice, unable to withstand the summer melt. There is much more too it all than that, such as freshening ocean surface from ice sheet melting and increased snow and rain, which can make it easier to freeze and act like a cap, prevent the more dense and warm salt water from reaching the surface. But it's safe to say the processes involved in sea ice growth and loss can be quite complex, and the Arctic and Antarctic can work in surprisingly different ways.
  10. 3 points
    There is a lot of fine and warm late summer weather on the Gfs 6z but there is also some humid thundery conditions, especially through the second half of the week further south when it's set to become very warm / sultry across the south of the UK, heavy rain in the south sweeps northwards into scotland by the end of the working week. Looking further ahead, the 6z shows high pressure in the ascendancy with nice warm temps comfortably into the mid 70's F and largely fine and sunny conditions but becoming more unsettled across northern UK later.
  11. 3 points
    Hey All, I've hopefully attached this right - this was a supercell over lake Garda, Italy 29/7. Level 1 warning at the time, and after this was taken, severe winds came across the lake and caused quite a bit of damage, with Parasols smapping and people's dinner going everywhere- awesome expierence! I'll post some more after this - WAs there from 20/7 until 3/8 - when I arrived (after a grueling overnight train from Paris to Verona), it was 36c at 9:00 am ... hot as hell for 5 days, then got very thundery as the temp started to drop a bit - mainly popcorn stuff though as the dynamics weren't there. In the second week, the Jet was racing overhead, and when cape was enough and convection wasn't getting shredded, this was the result - Sam
  12. 3 points
    HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS ISSUED AT 08:00 ON SUNDAY AUG 9TH 2015 THE CURRENT GENERAL SITUATION. A moist SW flow covers the UK today as weakening fronts move SE over the UK. Another front will move NE over Southern areas tonight followed by a fresher westerly airflow later tomorrow. http://www.wetterzentrale.de/pics/Rtavn001.gif MODELS-2 WEEK HEADLINE Remaining rather changeable with some rain at times. Some dry and at times warm, humid conditions are likely for all areas as well. THE GFS JET STREAM FORECAST The GFS Jet Stream Forecast shows the flow moving NE across Britain over the next few days moving SE and weakening.The main arm of the flow then dives SE towards Spain later this week with the UK lying under a trough. This pattern changes only slowly in Week 2 with what flow there is continuing to reside further South than is ideal for good weather across the UK. http://www.netweather.tv/index.cgi?action=jetstream GFS OPERATIONAL The GFS Operational Run today shows the SW or west flow of the next few days weakening away by midweek as pressure builds across Central areas midweek. A thundery Low pressure area is then shown to feed north from France and amalgamates with Low pressure from the NW by the weekend with the whole complex system lifting North out of Britain next weekend. So after a some rain at first Central regions dry up midweek before thundery showers in warm and humid weather affect the South. Later in the week bith thundery weather in the South and Low pressure fronts from the NW give an unsettled and cooler spell for all before the North see a fine settled period in the second week, at least for a time before a rerun of week 1 looks likely as thundery low pressure moves up once more from the South http://www.wetterzentrale.de/pics/Rtavn1441.gif http://www.wetterzentrale.de/pics/Rtavn3841.gif THE GFS CONTROL The GFS Control Run is quite similar in structure but is less bullish about the influence from both thundery low pressure from the South and the NW later this week with generally slacker conditions giving rise to less outbreaks of rain and more in the way of benign weather types right out to the end of the run. THE GFS CLUSTERS(14 Days) The GFS Clusters this morning for 14 days show quite an even split between fine conditions under a ridge especially over Southern Britain in two weeks time and an equal split in members who prefer more unsettled weather under Low pressure close to Northern Britain http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gefs&MODELLTYP=2&BASE=-&VAR=cpre&HH=372&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD= UKMO UKMO today shows a ridge of High pressure developing across Central Britain midweek with thundery low pressure moving up from the South. Then later in the week pressure falls from the NW too ending the run in a complex Low pressure zone near to South-east and NW Britain bringing cooler air to all with thundery rain at times next weekend. http://www.wetterzentrale.de/pics/Rukm1441.gif THE FAX CHARTS The Fax Charts this morning show a wrath of fronts crossing east and SE across Britain over the next 48 hours followed by a simplification by midweek as pressure builds across central areas and thundery Low pressure brings further fronts North into Southern Britain at the end of the week in warm and humid Easterly winds. http://www.weathercharts.org/ukmomslp.htm#t120. GEM GEM today follows a similar route to the rest edging thundery rain up into the South later this week as the current SW flow weakens over the coming days and pressure builds briefly across Central Britain. Thereafter Low pressure from both the SE and NW combine to bring a spell of more unsettled and cooler conditions as winds settle Westerly from next weekend. http://www.wetterzentrale.de/pics/Rgem2401.gif NAVGEM NAVGEM keeps the axis of low pressure further to the east than the rest with the same ridge as other output shows midweek lying across Central areas. With the axis further to the East less effect with regard to thundery rain or rain from the NW looks likely with drier weather and more sporadic showers likely for a time later this week before a North/South split develops again by the end of next weekend with most rain by then in the North and West http://www.wetterzentrale.de/pics/Rnvg1681.gif. ECM ECM this morning shows the thundery Low further to the West over France than NAVGEM with the resultant weather being more thundery over the South from midweek edging North. As pressure becomes slack and eventually High to the NE many northern areas will see the best of the conditions later in the period with some warm sunshine and mainly dry conditions. Southern and especially SW areas of the UK later will always lie at risk of further thundery conditions especially late in the period as pressure falls over the SW approaches. http://www.wetterzentrale.de/pics/Recm2401.gif ECM 10 DAY MEAN The ECM 10 Day Mean Chart from last evening maintains the general theme of Low pressure to the NW and High to the SW maintaining a slack Westerly feed across the UK with the best conditions likely to be towards the South outside of any thundery outbreaks in any warmth fed up from Europe http://www.wetterzentrale.de/pics/Reem2401.gif NOTABLE TREND CHANGES FROM PREVIOUS RUNS The models trend changeable today with various options between the models desiring a return to Atlantic airflow domination in the long term. 31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKMO & ECM The Verification Statistics of GFS, UKMO and ECM. This morning's verification statistics show ECM leading the way at 3 days with 95.9 pts followed by UKMO at 95.4 pts and GFS at 94.6 pts. At 5 days ECM is stll king at 86.0 pts followed by GFS at 84.2 and UKMO at 84.1 pts. Then at 8 Days ECM still leads at 58.1 pts over GFS's 54.1 pts. Finally at Day 10 ECM leads GFS at 40.0 pts to 33.2 pts from GFS. http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day3_PMSL_MSL_G2NHX.png http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day5_PMSL_MSL_G2NHX.png http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day8_PMSL_MSL_G2NHX.png http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day10_PMSL_MSL_G2NHX.prig MY THOUGHTS There is some coming together of the output this morning, certainly within the first week although with small synoptic differences still present from some output could have radical effects n local differences in weather at the surface. In general this week looks quite warm and humid especially at first and again from midweek in the South. early rain in the South should give way to brighter and fresher weather over Tuesday and Wednesday as ridge builds across Central Britain. Pressure will then fall across France and it looks increasingly like it could turn quite thundery across Southern Britain from midweek. In addition the ridge across Central regions where it could be quite a dry week will be superseded by Low pressure from both the SE and NW next weekend probably forming a Low complex near to our shores with a cooler and unsettled phase next weekend. This is where the togetherness in the models fall apart as a variety of options are shown then ranging from a return to a North/South split in conditions to a generally more unsettled period as Low pressure close to the North return westerly winds and rain at times for many. However, I strongly believe that Week 2 belongs in never never land at the moment and until the fine detail of the latter stages of this week are sorted Week 2 could go one of many ways at the moment. However, looking at what looks more certain this week many places will end up warm and humid but unless the sun breaks up a lot of the predicted large cloud amounts high temperatures will be very localised and when thundery rain comes along later in the week in the South some redress of balance in rainfall amounts between north and South looks likely. All in all then a typical August week to come with something for everybody but never overly cool or wet. Next update from 09:00 Monday Aug 10th 2015
  13. 3 points
    so where are they then? Are you referring to their predictions or summation of each month after the start of the next month. confused as to what you mean. that you have a cold bias is pretty obvious. I try to present an objective forecast when I post my thoughts using the 500mb anomaly charts.
  14. 3 points
    So is next summer.
  15. 2 points
    Not only that Stew, but in the Arctic climate section of the report it states that conditions have remained favourable for ice loss due to conditions 'very similar' to the dipole anomaly in the arctic for the last month. Inspite of this the chart presented as an average for July shows more ice extent than any of the last 4 years. I agree that it is dropping quicker now (upto last week) but is it going to break any record lows? It would seem that GW is getting more and more bullish with his posts and speculations on where it will end up for the Arctic, whereas for the Antartic which is still running 4th highest in the last 35 years, every small drop is greeted with a post basically claiming that the whole of Antartica is under threat from the ENSO events. I prefer to wait and see what the data actually brings before making any conclusions rather than to speculate (on either ice pack as GW has done above!) MIA
  16. 2 points
    The spectacular glaciated summit plateau of Saunders Island in NW Greenland surrounded by sea ice Image NASA
  17. 2 points
    Lovely post stainesbloke - it just summed up the day nicely! Me and Mrs Blessed also enjoyed a trip to the pub this afternoon and a nice bbq in the garden this evening and it was still 21C at 20.30. It doesn't get much better for a British summer's day! Hope we get a few more weekends like this before summer's end.
  18. 2 points
    I think NOAA is moving in the direction of the GEFs and relaxing the upper trough and allowing more influence from the Azores and slightly veering the upper flow. Which can only be good news for those living further north.
  19. 2 points
    These are the evening visitors to my garden, bless the little monsters!
  20. 2 points
    Everything has taken for ever this year to bloom, think the nights were a little cold for them earlier in the summer and we've had a dreadful pesky wind for what seems most of the summer months and so the baskets have taken quite a bashing. One plant that was splendid this year was my climbing rose, it was an absolute picture. Anyway this is my garden complete with a 50 year old tortoise playing with his pot
  21. 2 points
    That is a feature of any 8-14 in about 8 cases out of 10. The 'meaning' seems to show a less deep trough or intense high and lower values of both + and -ve heights. What one is looking for in the 8-14 is, either a marked change from the 6-10, rare that happens but it does now and then, or, a continuation of the 6-10 overall pattern, including moving troughs and riges if the wave length is the right length.
  22. 2 points
    It's really encouraging to see the gfs is sticking with a change to warm anticyclonic conditions during w/c 17th August with high pressure building in to bring a week of settled and warm / very warm weather to most of the UK, I hope this trend continues to firm up, great charts for week 2 on the Gfs 12z.
  23. 2 points
    The last vageries of 'high summer' are upon us now as we gradually slip towards late summer. The outlook remains mixed for all, and for the NW very much more of the same, with time fast moving on even if we do see a late summer lengthy warm settled spell; the summer as a whole will only go down as a very average one for many I suspect. For the SE perhaps better to describe as none too bad, but certainly nothing special... for the NW probably 'below par' best way to describe things but not terrible (at least in terms of rainfall, though temps admittedly have been very poor). My interest in the weather traditionally reaches its slumber point as we move through latter part of August and reaches its absolute low point around the middle of September.. mainly because the expectation and high hope of early-mid summer becomes a distant memory, but likewise the expectation and hope of proper autumnal weather can never manifest itself properly until later in September. I find it a trying period in this respect. Mid March also carries a similar feel but not to the same extent, as we can see some interesting topsy turvy weather then from one extreme to another, something that can't really be said for early-mid September, though yes we can still achieve very high maxima low 30's even in some spots, but no real cold weather to counter balance things. Just thought I'd share some ruminations..
  24. 2 points
    Update for the week to August 8th The current 5 day mean is on 6,383,400km2 while the 1 day extent is at 6,238,000km2. The daily anomaly (compared to 81-10) is at -1,359,140km2, an increase from -1,321,970km2 last week. The anomaly compared to the 07, 11 and 12 average is at +453,267km2, an increase from +365,200km2 last week. We're currently 4th lowest on record, up from 5th last week. The average daily change over the last 7 days was -79.9k/day, compared to the long term average of -74.7k/day, and the 07, 11 and 12 average of -96.2k/day. The average long term change over the next week is -62.7k/day, with the 07, 11, and 12 average being -87.7k/day. The loss so far this August is the 12th largest on record. To achieve the largest monthly drop, a daily loss of at least 91.8k/day is required, while the smallest drop requires a loss of no more than 25.2k/day and an average drop requires a loss of 48.3k/day.
  25. 2 points
    Beautiful mainly sunny morning here and feeling very warm, sadly this afternoon spoilt by loads of vile mid level muck moving in from the NW. May be some breaks in the cloud still though, hopefully. Made the most of the lovely morning by going for a 5 mile walk around Windsor Great Park followed by a cheeky pub lunch :-) Edit: It's 5pm and the cloud did indeed break up nicely, with temps up to a very pleasant 27C. Perfect temps and it'll be another BBQ dinner this evening here, yay!
  26. 2 points
    Not necessarily, look at Autumn 2009. November was very mild and very stormy and this continued into the 1st part of December. The rest is history!
  27. 2 points
    To me, as we head into mid-August, summer typically is in its final throes. Yes, we get exceptions like 2003, but generally speaking Autumn is not far away. Mornings can have a slight chill, like mushy said plants are past their aesthetic best and the evenings are getting increasingly dark.
  28. 2 points
  29. 2 points
    Autumn looks like starting settled and sunny before turning very stormy come November, yup winter 2015-2016 is already over It is looking like a mild, stormy winter, if this guy is on the ball. http://www.weatherweb.net/wxwebtv2.php
  30. 2 points
    I'm trying, but people keep on saying summer is nearly over!
  31. 2 points
    Come on guys, "miserable season" this, "depressing season" that...just enjoy the summer, will you!
  32. 2 points
    The 18z GFS operational takes the deported heat as far north as Svalbard (much diluted by then of course): This is largely down to the Atlantic trough jumping back south again when compared with the 12z. Seems that its behaviour is anyone's guess at the moment.
  33. 2 points
    indeed. i would class the misery months as december, january and febuary, not to keen on november either as you know what lies ahead, things reverse , the summer haters are always on edge in summer in case any humid stifling heat is pulled in on a plume, likewise I am on edge in winter in case any bitter frigid air is pulled in from the east and stagnates over us, both tend to fail though apart from the odd occasions
  34. 2 points
    Where the UK continues to be affected by periods of unsettled weather associated with active troughing and over the eastern Atlantic ocean, parts of central and northern Europe are experiencing much hotter and drier weather. In fact, Germany touched upon its national heat record from 2003 (40.3*C). This weather is associated with anomalous ridging (high pressure activity) both near the surface and at 500 hPa over Eastern Europe. On the last few pages of this thread an interesting discussion has been going on about this ridge and the connection to El Nino. In order to explore this link, and (hopefully) find a few answers, I will examine some teleconnections, as well as have a look at the general circulation pattern. Bridging the gap A nice bridge to my previous post (discussing the ocean and the NAO in connection with troughing over the UK), and the current topic is that we are now not looking at the Eastern Atlantic trough and small sea surface temperature anomalies in the Atlantic, but the neighboring ridge and a much greater phenomenon - ENSO. Here is the link to my previous post: https://forum.netweather.tv/topic/83477-model-output-discussion-1st-july-onwards-18z/page-47 Furthermore, on the same page, Knocker posed a key question for the current discussion, and a first start in our search for an answer: To clarify: Michael Ventrice is a leading scientist in the field of teleconnections related to weather. And the image shown in the quote is an ECMWF forecast for 30 days out of surface temperature anomalies, NOT a representation of average surface temperatures during an El Nino event. Link real or nonsense? Validating the link is crucial here, so to test that below are 500 hPa height anomalies during El Nino events in summer: 500 hPa height anomalies during an El Nino summer, composed by averaging over various El Nino years. Courtesy: NOAA. Unexpectedly (at least for me), there are negative rather than positive height anomalies present over central and eastern Europe.This means that on avearge, during an El Nino summer, the 500 hPa heights are lower than usual. This would coincide with more low pressure activity than usual. In short, this is contradicting what I initially expected (namely that an El Nino summer correlates positively with 500 hPa height anomalies over central Europe). Does this mean the answer is that there is no link? It is good to realize that we are currently facing a rather strong summer El Nino, and in the plot above also weak El Ninos are taken into account. Therefore, it might pay off to look only at strong El Nino events (although one could question the value of comparing only one year). Below are the 500 hPa height anomalies for the summer of the El Nino event of 1997: 500 hPa height anomalies during 1997 between June and August. Courtesy: NOAA. In this particular El Nino event, we do see strong positive 500 hPa height anomalies covering the whole of Europe. However, does one year's match make the link to be true? This is a difficult question, where further examination of other strong El Nino years could be very valueable. Finding an explanation for a phenomenon that may or may not be there is even more hazardous. Therefore, for the remainder of this post I will attempt to explain the current anomalous ridging over central Europe without looking at past analogues. A rather amplified atmospheric state In order to explain the current ridging over central Europe, it is good to take a look at the big picture. As such, below are the 100 hPa heights of the Northern Hemisphere (in order to retain the most clean view): ECMWF height analysis at 100 hPa as of 06-08 12 UTC. Note that even though the given level is near the stratosphere, the general pattern nicely matches the pattern at 500 hPa. The red lines indicate the position ridges, whereas the blue lines indicate the position of troughs. What can be seen is that, if one follows the 1648 dam line, the pattern is rather wavy/amplified. In other words, there are a lot of rather deep troughs (isolines pointing towards the equator) and strong ridges (isolines pointing towards the poles) present. In my post on the 25th of June, I treated that subject in somewhat more detail, that post can be found here. If we look into somewhat more detail (towards our region) we can see a deep trough extending southward just west of mainland Europe, while a potent ridge is positioned all the way up from central Europe to Siberia. This is a pattern that has been observed a lot during this summer. One key conclusion can be driven from this is that the ridge over central and eastern Europe is present throughout the troposphere, and that it may be seen as a blockade in the atmosphere. The same applies for the trough just west of Europe. Arctic oscillation as a measure: high pressure over the poles Another way to look at this 'waviness' is the arctic oscillation. When this oscillation is positive, little 'waves' are present in the atmosphere resulting in a generally east-west circulation with weak to no dominant ridges or troughs. On the other hand, when the AO turns negative, lots of meanders (visualized by troughs and ridges) are present, resulting in lots of blockades and north/south orientated flow. During a large part of the summer, the AO has been negative: Arctic oscillation trends over the past few months (courtesy: NOAA) What can be seen is that the AO has been negative a lot, indicative of a rather amplified flow. Therefore, anomalous ridges and troughs are more often than not occurring. Linking back to the ridge over Europe, the negative AO nicely coincides with the anomalous ridge present over central Europe. In terms of the 500 hPa pattern over the pole itself, this pattern could be explained by the fact that the North Pole has seen higher than average heights (so higher than average pressure) during most of summer. This acted as a catalyst of the amplified flow. More about this can be found here: https://www.aer.com/science-research/climate-weather/arctic-oscillation What can be seen in the AO forecast in the image and the article above (the red lines are a forecast ensemble of the GFS model), is that the AO is going to turn positive. In other words, the flow at the midlatitudes is forecast to become more zonal (east-west oriented, with less strong ridges/troughs) Europe ridge not responding So that would mean easing of the ridge over central and eastern Europe? Well, this is not the case. In fact, the ridging only seems to stubbornly maintain itself, only changing some in shape. This is illustrated in the GFS ensemble 500 hPa heights chart below: GFS ensemble 500 hPa heights and surface level pressure as of 18Z 07-08 T+240. As can be seen here, there is still a strong ridge present at 500 hPa (orange and red colours) over Scandinavia. Concluding, the decreased 'waviness' of the atmosphere does not seem to lead to a relaxation of the ridge over central Europe. The 'waviness' of the atmosphere can therefore not be seen as a lead contributor to the ridge. Taking a different approach: Atmospheric Angular Momentum linked to El Nino as a key player? For a further search towards an answer, we might want to turn our eyes on the AAM budget, reflected in the Global Wind Oscillation (GWO). The AAM is, in short, the velocity of the movement of the atmosphere relative to the earth. It is well-known that during an El Nino event, there are often higher than usual AAM values. This is also the case as of speaking, and will remain the case for the next weeks: GWO analysis and forecast (in green). Courtesy: University of Albany. The upper part of the diagram indicates high values of AAM, while the lower part of the diagram indicates lower values of AAM. As can be seen here, the AAM is currently positive, and will remain positive, despite the GWO making some orbits. Unfortunately, this is as far as my knowledge allows me to go. Possibly somebody else can make or break the theory that this ridging over central Europe is associated to El Nino via the AAM budget, of course assuming that the link exists at all. It would be greatly appreciated! Conclusion In this post I came to the conclusion that the anomalous ridge over central Europe may not be directly coupled to El Nino, despite me initially thinking otherwise. Furthermore, we have seen that a rather amplified flow has been associated to the ridge, yet this waviness of the atmosphere did not seem to be directly linked. This was because even though forecasts pointed towards less 'waviness' in the atmosphere, the ridge over central Europe was not weakening as would be expected. Finally, I touched upon the atmospheric angular momentum and the link with El Nino as being a possible driver. And yet, the only thing this post seems to do is raise more questions, rather than a definite answer to the question whether El Nino is related to anomalous ridging over Europe. This is the interesting part of science, though, as unveiling one aspect of a phenomenon reveals even more parts to discover! Hopefully, despite the lack of a definite answer, this post is an interesting read, and more contributions/theories/corrections are greatly appreciated as always . Sources: http://www.earthgauge.net/wp-content/CF_Arctic_Amplification.pdf https://www.aer.com/science-research/climate-weather/arctic-oscillation http://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php https://twitter.com/MJVentrice http://www.wetterzentrale.de/topkarten/fsavneur.html http://www.atmos.albany.edu/student/nschiral/gwo.html http://www.esrl.noaa.gov/psd/enso/compare/ http://www.geo.fu-berlin.de/en/met/ag/strat/produkte/winterdiagnostics/ http://www.usclivar.org/working-groups/mjo/science/mjo-atmospheric-angular-momentum-length-of-day http://www.iers.org/SharedDocs/Publikationen/EN/IERS/Publications/tn/TechnNote26/tn26.pdf?__blob=publicationFile&v=1
  35. 1 point
    Must be dog crap Paul! Big Innes
  36. 1 point
    Poor nuts and melons ! Now see this is why I had to make a return .... To check how your nuts and melons were coming along
  37. 1 point
    I'm not well versed in making the NOAA plots so hope this is air temp anomaly for summer to date. It sure wouldn't go down in my records as an average British summer.
  38. 1 point
    It's thought that the ozone hole caused a cooling of the stratosphere which enhanced the SH polar vortex, promoting a positive Antarctic Oscillation. This tends to push ice away from the continent.
  39. 1 point
    theres been plenty of cold mornings in the summer.. so whats the difference?.. you can get plenty of warm days in September, august as been excellent so far.
  40. 1 point
    Simon Keeling's thoughts for September and October *September* Higher than normal pressure is expected to be the dominant weather pattern through September. Indications are that this will tend to be situated to the east of the country. Conditions are expected to be drier than normal, probably more so later in the month. Temperatures are also likely to be above normal for the time of year, although not by much. Later on in the month we expect the risk of air frosts to increase and it may be that periods of rain affect Scotland and Ireland from time to time. *October* A reversal in conditions in October as low pressure deepens and becomes a predominant feature. Strong winds and heavy rain are likely, especially in more central and southern parts of the country where the jet stream will be strongest. Temperatures will be near normal overall. whilst rainfall totals as a month will be close to normal, although tending to be focused in the second half of the month. Probably drier in Scotland, although still rain to come here. http://www.weatheronline.co.uk/cgi-app/reports?LANG=en&MENU=seasonaloutlook&DAY=20150717
  41. 1 point
    Just 7.2 mm of rain in the first week of this month which makes it the driest first week in August since 2005. Yesterday, with a maximum of 22.6c, was the warmest day since July 1st.
  42. 1 point
    thanks lilies are easy to grow in pots, they like being in pots, just dont over water them and kill lily beetles (i do it by squashing them between finger/thumb). you can buy them easily online, several producers (parkers, hardys, hydes) have online catalogues where you can order bulbs for delivery and at really cheap prices too. far greater variety and much much cheaper then garden centres.
  43. 1 point
    but to be fare, frosty always posts charts that support totally what hes saying. posts that refer to the poorest possible outlook only appear to chose one chart to 'prove' their negetive spin, and overuse those smileys (which add nothing to the point being made). as i see it, this summer has been one where ridging off the azores high was often predicted to become more of a feature as it developed into a proper displaced high over the uk - but its never developed that way and the ridges have all collapsed, failing to develop and produce us all a decent lengthy settled spell. frosty and others didnt have to look too hard to find numerous summery charts on nearly every run , it was there in front of our eyes! on many occassions. those sceptical of the predicted pressure rises have been proven to be right in their scepticism, but on the other hand their alternative wet predictions too have failed to become reality. looking at the models, i can see this pattern continuing, with 'spoiling rain' spells between more settled, dry, pleasantly warm, sunnier spells. no heatwave, no monsoon.
  44. 1 point
    Taken from a friends Facebook: Malta storm.
  45. 1 point
    HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS ISSUED AT 08:00 ON SATURDAY AUG 8TH 2015 THE CURRENT GENERAL SITUATION A ridge of High pressure lies NE across the UK today. The ridge collapses SE tonight and tomorrow to lie in the English Channel while a fresh SW flow develops over the UK with troughs weakening as they move SE over Britain tonight and tomorrow. http://www.wetterzentrale.de/pics/Rtavn001.gif MODELS-2 WEEK HEADLINE Remaining rather changeable with a little rain at times. Some dry and at times warm conditions are likely for all areas as well. THE GFS JET STREAM FORECAST The GFS Jet Stream Forecast shows the flow moving NE across Northern Britain with the axis gradually feeding further SE over the coming days. The flow then steadily weakens close to Southern Britain before becoming generally quite slack though still troughed well South over the Atlantic and later towards the UK once more.. http://www.netweather.tv/index.cgi?action=jetstream GFS OPERATIONAL The GFS Operational Run today shows the ridge across the far South of the UK weakening as the fronts moving down from the NW on Sunday and Monday weaken too and the accompanying SW flow lightens. occasional rain and drizzle will largely break up into showers by Tuesday. at the same time pressure falls from the South and a thundery spell of weather develops across Southern and Eastern Britain with a drier spell in the North. Then Westerly winds with rain at times looks likely as Low pressure to the North and NW returns with the best of the drier and warmer weather back towards Southern Britain late in the run. http://www.wetterzentrale.de/pics/Rtavn1441.gif http://www.wetterzentrale.de/pics/Rtavn3841.gif THE GFS CONTROL The GFS Control Run looks broadly similar, certainly in the first week with the ridge of High pressure developing across the North towards midweek and a thundery low to the SE. The weather turns changeable generally at the end of Week 1 before week 2 shows a mix of a High pressure ridges followed by a Low pressure cell moving slowly North-east or North over the UK to leave the UK in a NW flow at the end of the run. THE GFS CLUSTERS(14 Days) The GFS Clusters this morning for 14 days are not quite as good as yesterday morning's today as they indicate High pressure likely to be parked out over the Atlantic with a ridge only towards Southern Britain but with more influence from a West or NW flow over all areas with rain at times particularly towards the North and West. http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gefs&MODELLTYP=2&BASE=-&VAR=cpre&HH=372&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD= UKMO UKMO today shows increasingly thundery conditions developing next week as the SW flow weakens from all but Scotland by Tuesday with warm and humid air in place. Wednesday sees Low pressure edge into Southern Britain from Europe continuing in situ up to the end of the week with thundery showers in warm and close conditions while the North sees the best of the drier weather and just occasional rain on Thursday from an Atlantic trough. http://www.wetterzentrale.de/pics/Rukm1441.gif THE FAX CHARTS The Fax Charts this morning show a series of troughs weakening as they move SE into Southern Britain over the coming days. They remain active enough to give cloud, occasional light rain and eventually thundery showers as humid and unstable air reinvigorates them by midweek when the North sees drier and brighter conditions. http://www.weathercharts.org/ukmomslp.htm#t120. GEM GEM today shows a SW flow with embedded troughs too moving SE into Southern Britain early next week. A ridge then develops across Central Britain but the old troughs get reinvigoration from thundery instability moving up from Europe close to the SE. So thundery showers become a risk in the South from midweek with the best weather in the North before a gradual change to cooler and more changeable conditions with rain at times look likely from later next weekend as Low pressure feeds slowly East over the UK from the West. http://www.wetterzentrale.de/pics/Rgem2401.gif NAVGEM NAVGEM follows a similar route in bringing a thundery continental Low North close to SE Britain midweek with warm and close conditions developing after the innitial days of cloud and a little rain early next week. After the first few days the best of the drier and brighter conditions transfer to the NW of the UK close to a ridge from the SW.. http://www.wetterzentrale.de/pics/Rnvg1681.gif. ECM ECM this morning shows the thundery Low further to the East and as a result probably only affecting SE Britain with dry and bright weather elsewhere and pleasantly warm in any sunshine. Then as winds settled NW'ly for a time it will likely become a little cooler with just a few showers in the East before a North/South split in the weather gradually returns with rain at times for all but more especially in the North and West with longer dry spells for the South and SE. http://www.wetterzentrale.de/pics/Recm2401.gif ECM 10 DAY MEAN The ECM 10 Day Mean Chart from last evening shows a Westerly feed across the Atlantic towards the British Isles with no doubt some influence across the UK given Low pressure lies to the NW and High pressure near the Azores. The likely result is a familiar tone of rain at times, chiefly in the North and West with longer drier, warmer and brighter weather towards the South and SE.. http://www.wetterzentrale.de/pics/Reem2401.gif NOTABLE TREND CHANGES FROM PREVIOUS RUNS The models trend changeable today with various options between the models desiring a return to Atlantic airflow domination in the longer term. 31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKMO & ECM The Verification Statistics of GFS, UKMO and ECM. This morning's verification statistics show ECM leading the way at 3 days with 95.9 pts followed by UKMO at 95.5 pts and GFS at 94.7 pts. At 5 days ECM is stll king at 85.9 pts followed by GFS at 83.9 and UKMO at 83.8 pts. Then at 8 Days ECM still leads at 58.3 pts over GFS's 53.5 pts. Finally at Day 10 ECM leads GFS at 39.7 pts to 34.0 pts from GFS. http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day3_PMSL_MSL_G2NHX.png http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day5_PMSL_MSL_G2NHX.png http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day8_PMSL_MSL_G2NHX.png http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day10_PMSL_MSL_G2NHX.prig MY THOUGHTS Details of large scale changes are non apparent again this morning as the models serve up yet another cocktail of options on specific weather events over the coming two weeks, none of which have major implications for any one area in particular. In sequential order it looks like a SW flow will develop across the UK over the next three days with a series of troughs moving SE across the UK, weakening as they do and becoming slow moving over the South early next week but delivering occasional rain and drizzle where they lie. Behind them a ridge builds across the North but humid and thundery air over Europe looks like reinvigorating the troughs in the South to increase the risk of heavy and thundery showers for the rest of next week. While warm or locally very warm cloud amounts will deter the very highest temperatures but it is likely to feel close and humid. The North at this time look at long last likely to have some reasonable if not memorable conditions at this time. Then all models seem to then want to use this thundery Low to the SE as a catalyst to return a more Atlantic influence back across the UK through week 2 to a greater or lesser degree depending on which model you look at. What this would likely mean at the surface is a fall back in temperature to nearer average, less humidity but dare I say it a more North/South split in the weather again with rain at times for all but a lot of dry and bright weather in between especially for the South. The models seem to be really struggling at the moment which is quite a common occurrence when pressure conditions are generally quite slack as they look like being over the second half of next week meaning long term projections come with a lower than normal degree of confidence. I will say though that the ECM longer term projection illustrated by it's 10 day mean chart each day has been consistent in maintaining a loose westerly bias across the UK at the 10 day time point for several weeks now and this continues this morning. It's verification statistics listed above have shown this to be the right call and alone has not been sucked in by High Summer synoptics occasionally thrown out by some of the other output only to be watered down in later runs. So where that leaves us is in a continuing changeable theme of weather which looks much better than recently for the North but much the same for the South as occasional rain or showers looks the order of the next two weeks for many and while warm and humid but typical August conditions look likely there may well end up a more even distribution between amounts of rainfall having fallen North to South at the end of the next two weeks than has been the case so far this Summer. Next update from 09:00 Monday Aug 10th 2015
  46. 1 point
    I had to share this as it is amazing http://www.liveleak.com/view?i=20b_1438753392
  47. 1 point
    Ha, yea no doubt, thought I'd update what happened anyway, we were all hoping for a bit more but the official forecasts were actually spot on. The best lowest elevation snow of the 21st century anyway for us .We have our own versions of Mr Madden springing up so sometimes its hard not to get slightly over excited.
  48. 1 point
    I rather like the story when Cilla's father demanded a name change when Epstein took her on. When Epstein agreed to take her on, her father — who was required to sign the contract because she was under 21 — told him he wanted her name changed back to White, otherwise his fellow dockers would not believe she was his daughter. Epstein declined and, according to Cilla, her father’s workmates then nicknamed him The Frustrated Minstrel “because he didn’t know if he was Black or Whiteâ€.
  49. 1 point
    Lynn Anderson has died aged 67
  50. 1 point
    Short answer The short answer to your question is yes, the presence of low pressure (at higher altitudes, being coincident with very cold upper air), makes the air more unstable, as the gradient in temperature between the surface and higher altitudes becomes larger. Long answer The long answer requires some explanation on stability. To avoid things from getting too complex, I will not go into detail about Skew-T diagrams. (If one wishes to have an explanation via Skew-T charts, just ask ) Stability of the atmosphere (Un)stability has to do with the 'tendency' of a parcel of air to rise from a certain position (in altitude) or to stay at the same position. This tendency is related to the temperature a parcel has compared to its environment. Imagine a parcel starts to rise from a certain altitude (say, 1000 meters). The parcel then cools adiabatically (meaning it does not 'mix' with its environment) up to a certain height. If a parcel then finds itself being cooler than its environment (stable conditions), it will drop back to its original position (remember that a certain volume of cold air is in general heavier than an equal volume of warm air). However, if the parcel is warmer than its surroundings (unstable conditions), it will continue to lift to even higher altitudes until it reaches a height when the parcel becomes saturated. This height is the height where clouds start to form. Thereafter, the parcel will still continue to rise up to where it finds itself in an environment that is warmer than the parcel itself. (Note that the cooling process during ascent of a parcel is different when the parcel is saturated, but goes too far to treat this in detail). The parcel then stabilizes, and this can (under great simplifications) indicate the height of a cloud. What this comes down to is that when the air is unstable, showers are easier to form based on the parcel analogy described above. A good measure of stability is the change of temperature with height. If the temperature drops sharply with height, the atmosphere can be considered unstable (referring back to the parcel analogy). When the temperatures decreases only weakly with height or even increases with height, the atmosphere is stable (from the parcel analogy: a parcel will find itself colder than its environment after ascent, meaning it will drop back to its original position). To illustrate this, below is a series of images showing the parcel analogy: Stable situation Unstable situation In the images above, the x-axis indicates the temperature, while the vertical axis (y-axis) denotes height. For both graphs, the red line indicates the change in temperature over height of the environment of a certain parcel (technically spoken: lapse rate). Note that the environmental temperature drops much more with height in the unstable situation than in the stable situation. The black dot indicates a parcel on a random level. The arrow pointing to the upper-left stands for the adiabatic rising (and the accompanied cooling) of this parcel. For both images, this parcel cools at a same rate (so the black arrow has the same slope to the left on both images). As can be seen in the stable situation, the parcel becomes colder than its environment after rising. Therefore, it is being forced downward again. On the other hand, in the unstable situation, the parcel becomes warmer (and thus lighter) than its environment, indicating the parcel will continue to rise. Temperature difference representation between surface and aloft Coupling the part given above back to the presence of low pressure at higher heights and stability, one can realize that the difference in temperature between the surface and aloft (I'll be using the 500 hPa level, being about 6 km, as a reference for now) must be very large in order to have an unstable atmosphere. If the atmosphere can be more or less unstable when the temperature at the surface stays the same, the temperature at 500 hPa has to vary accordingly. In other words, changes in stability can be explained by variations in temperature at 500 hPa level. Simplifying a bit, one can assume as a general rule that low pressure activity at higher altitudes is accompanied by lower temperatures at that same level. (more in-depth explanation can be found here). This means that, in general, low pressure at higher altitudes indicates the atmosphere is more unstable than when high pressure is present at higher altitudes (and thus showers are by approximation more likely to form when low pressure is present at higher altitudes) Seasonality in stability An important difference between summer and winter regarding stability is that the surface is usually colder during winter than summer. This means that the upper air has to be colder in winter to acquire instability than during summer. Combing to current weather The weather that we are about to observe this Thursday up to the weekend is a very nice example to illustrate the relation between stability and the presence of low pressure at higher altitudes. Therefore, given below is the pressure forecast of the GFS for next Thursday: GFS surface level pressure and 500 hPa heights (colours), 18Z T+48 It is important to focus solely on the 500 hPa heights, indicated by colours. As a rough guide, purple/blue colours indicate low heights (lower pressure activity at 500 hPa height) while yellow/red colours indicate high heights (high pressure presence at 500 hPa height). Note that there is a very deep trough (low pressure area) present at 500 hPa height over Western Scandinavia and Northeastern UK. Referring to the explanations, low pressure at 500 hPa should coincide with lower 500 hPa temperatures. Much higher heights (relatively higher pressure) are present to the southwest, west and north of the UK. Therefore, the 500 hPa temperatures for the same timeframe (from the GFS forecast) are given below: GFS 500 hPa temperatures, 12Z T+54 The runs of the GFS are two different ones (18Z above, 12Z below), but they are valid for the same timeframe. Since big changes between runs for 2 days out are not likely, I'll therefore assume that both runs show the same situation. Note that there is a large swathe of very cold 500 hPa temperatures present to the east of the UK (down to -38*C). This is associated with the very deep trough present to the east and over the UK. Much warmer 500 hPa temperatures can be found to the south and west of the UK, while the 500 hPa temps are also slightly warmer to the north of the UK. The surface temperatures do not vary much in the neighbourhood of the UK at this timeframe (except for land/sea effects). The surface temperature chart for this Thursday can be found here. Thinking of the parcel analogy given in the beginning of this post, it becomes evident that showers are more likely to develop over or to the east of the UK than to the north, west or south (assuming equal surface temperatures). Northerlies and stability Regarding wind, there are northerlies present over and to the north of the UK, while to the east of the UK there is barely any wind. (you can find the wind forecast from the GFS here). However, as we can see above, the air to the north of the UK is less cold than over the UK itself. This means that despite the fact that the northerlies are stronger to the north of the UK are stronger than the ones over the UK, the air over the UK is more unstable (due to the lower upper temperatures). Exceptions One possible exception is the presence of a polar low. Such systems may pop up out of nowhere and yield a lot of snow, being completely overlooked by global models. Quoting from s4lancia: Summary To summarize the relationship: low pressure at high heights is coincident with cold upper air, yielding a bigger temperature difference between the surface and aloft. This yields a more unstable atmosphere. It has to be kept in mind, though, that this relationship is simplified, so it does not have to match the actual conditions in any case. Conclusion Even a very short question can have a very long answer, and in fact there was much more that possibly could have been told about this. I hope this answers you question sufficiently . If something is not clear, do not hesitate to ask! Furthermore, I am by no means an expert on this subject, so any additions/corrections are also very welcome! Finally, if one would like some explanation about this via Skew-T diagrams, that's possible (probably with some delay ). A good read about Skew-T diagrams, which could also serve to visualize stability, is given below: https://forum.netweather.tv/topic/16002-a-simple-guide-to-understanding-skew-t-diagrams/ EDIT: Added graphical representation of stability. Sources: http://www.wetterzentrale.de/topkarten/fsavneur.html http://www.keesfloor.nl/weerkunde/10neerslag/10neerslag.htm https://forum.netweather.tv/topic/27989-how-to-try-and-forecast-snow/ https://forum.netweather.tv/topic/16002-a-simple-guide-to-understanding-skew-t-diagrams/ http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=ukuk&MODELL=gfs&MODELLTYP=1&BASE=-&VAR=z500&HH=48&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD=