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  1. 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!
  2. 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
  3. 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
  4. 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.
  5. 3 points
    So is next summer.
  6. 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!
  7. 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.
  8. 2 points
  9. 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
  10. 2 points
    I'm trying, but people keep on saying summer is nearly over!
  11. 2 points
    Come on guys, "miserable season" this, "depressing season" that...just enjoy the summer, will you!
  12. 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.
  13. 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
  14. 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
  15. 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
  16. 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.
  17. 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.
  18. 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.
  19. 1 point
    Taken from a friends Facebook: Malta storm.
  20. 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
  21. 1 point
    I had to share this as it is amazing http://www.liveleak.com/view?i=20b_1438753392
  22. 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.
  23. 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€.
  24. 1 point
    Lynn Anderson has died aged 67
  25. 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=
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