Model output discussion - 20th Feb onwards

[William Grimsley]

15 minutes ago, knocker said:

A showery regime for a day or two before the next frontal system sweeps in Friday/Saturday. After that low pressure to the SW will become the dominant feature for a little while.

Which means more warm and thundery weather!

[mb018538]

Both GFS and ECM firming up this morning on the idea of heights lowering over greenland in the 7-10 day period. Pressure patterns look quite slack there after, which could lead to a whole range of outcomes.

[Summer Sun]

With the low parking its self to the south west of the UK it will start and draw in some milder air for the start of next week in the south

Cooler mid week afterwards its more mixed

Rather cold Friday night into Saturday in the north the MAX temps for some are minus double figures!

[Gibby]

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS ISSUED AT 09:00 ON WEDNESDAY APR 6TH 2016

THE CURRENT GENERAL SITUATION A cool NW flow over the UK will weaken as a weak trough clears SE over England this afternoon with an area of slack pressure ahead of an occluded front approaching Western and SW Britain later tomorrow.

http://www.wetterzentrale.de/pics/Rtavn001.gif

CURRENT SNOW FORECAST AND FREEZING LEVEL OVER THE UK The freezing level across the UK will remain below average for this time in April hovering around the 3000ft mark for much of the time though rising briefly across the SW later tomorrow before falling to as low as below 2000ft behind an occlusion on Saturday. As a result some snowfall is expected in showers above 1000ft today and possible 600ft on Saturday in the West.

http://www.snow-forecast.com/maps/dynamic/uk

http://www.natice.noaa.gov/pub/ims/ims_gif/DATA/cursnow.gif

MODELS-2 WEEK HEADLINE Unsettled with showers or spells of rain with some brighter spells too especially over the North. Near average or slightly below average temperatures. Perhaps warmer later in the SE.

THE GFS JET STREAM FORECAST  The Jet Stream is shown to maintain a trough or circulation to the South of  the UK over the next week to 10 days with the Jet flow only slowly recovering it's way Northwards in a NE flow over the UK at the end of the period.

http://www.netweather.tv/index.cgi?action=jetstream

GFS OPERATIONAL The GFS Operational Run today shows a lot of cyclonic conditions across the UK over the first week. With Low pressure to the SW the UK will be subject to areas of rain and showers moving up from the SW periodically with some quite chilly conditions across the North. Then from the beginning of Week 2 the unsettled and cool conditions will slowly give way to drier and brighter weather especially towards the South and East with the unsettled weather restricted towards the North and West by the end of the period.

GFS CONTROL RUN The GFS Control Run is less optimistic in the second week as Low pressure after a brief lull re-invigorates and moves across the UK from the West with rain and showers for all still with just a hint of better weather moving in from the West and SW right at the end of the period.

http://www.wetterzentrale.de/pics/Rtavn1441.gif

http://www.wetterzentrale.de/pics/Rtavn3841.gif

http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=144&mode=0&carte=0

http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=384&mode=0&carte=0

GFS ENSEMBLE DAY 14 DATA  The GFS Clusters today show a Low pressure bias again at Day 14 though positioning and influence to what areas is harder to interpret with a 20% cluster indicating a more High pressure based pattern at that point with drier and quieter conditions as a result.

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 The UKMO model this morning shows Low pressure a little less influential as we move through the start of next week as it's positioning seems further to the SW than on previous runs and while some rain and showers is likely across the South and SW in particular some dry and breezy weather is likely in the North where it will feel cool. This period of relatively unsettled conditions then looks like continuing as we move towards the second half of next week.

http://www.wetterzentrale.de/pics/Rukm1441.gif

THE FAX CHARTS The Fax Charts show Low pressure setting up shop down to the SW of the UK over the weekend and start to next week with rain and showers spilling North across the UK from time to time occasionally accompanied by strong and cool SE winds while some warmer brighter periods also look possible especially towards the East and North.

http://www.weathercharts.org/ukmomslp.htm#t120

GEM GEM today continues it'e recent pattern of maintaining it's unsettled feel throughout the next 10 days with Low pressure dominant down to the SW at first then after a brief respite towards the middle of next week we see further Low pressure across the UK later which will maintain an unsettled and sometimes cool feel to conditions with rain and showers for all right out to day 10.

http://www.wetterzentrale.de/pics/Rgem2401.gif

NAVGEM NAVGEM today also maintains a very unsettled outlook with Low pressure down to the SW influential throughout. Rain or showers would be the order of the day with some longer spells of both wet and drier conditions for all the latter especially in the early part of the week in the North while  by the end of the run all areas look at risk of some strong winds and rain.

http://www.wetterzentrale.de/pics/Rnvg1681.gif

ECM ECM shows largely unsettled conditions continuing over the next week as Low pressure slips South to lie to the SW of the UK. Rain and showers can be expected for all through this period through the far NE may see the least of this while it is cold in a raw East wind. Some warmer and drier interludes could occur between the showers in the South. Then towards the end of the period a change in the charts indicate dry and settled conditions under UK based High pressure having developed with sunny spells and the risk of slight night frosts likely should this pattern evolve.

http://www.wetterzentrale.de/pics/Recm2401.gif

ECM 10 DAY MEAN (12z) The 240hr mean Chart from last night shows Low pressure further to the West and SW than of late at 10 days with resultant milder Southerly winds and rain or showers restricted towards the South and West rather than elsewhere possible if this develops as shown.

http://www.wetterzentrale.de/pics/Reem2401.gif

NOTABLE TRENDS & CHANGES FROM PREVIOUS RUNS A changeable and Low pressure driven period of weather for all is maintained from the models once more this morning though there is a trend towards improvements later.

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKMO & ECM The verification Statistics of GFS, UKMO and ECM show at 24 hours ECM ahead at 99.6 pts with UKMO at 99.5 pts and GFS at 99.4 pts.  At 3 days ECM is leading with 97.6 pts to UKMO's 97.2 pts while GFS lags behind at 96.1 pts. At 5 days ECM leads with 90.2 pts to UKMO at 88.9 pts and GFS at 85.5 pts. Then at 8 Days ECM has the leading spot from GFS with 66.0 pts to 61.3 pts. Finally at Day 10 ECM has the lead from GFS with a score of 44.8 pts to 41.4 pts.

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day1_PMSL_MSL_G2NHX.png

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.png

MY THOUGHTS  There are slow changes shown within the output again this morning but at least such changes do appear to be leaning towards somewhat better conditions over all developing late in the period. If these improvements are to verify we have to lose the deep trough expected to develop down to the SW of the UK in a few days time where it looks in no hurry to move from for some considerable time. Nevertheless, some output has placed this feature a little more to the SW today and if this is so some warmer continental air may be allowed to filter across the South at times with less in the way of rain and showers too away from the SW. It looks like the North will stay cool under an Easterly feed, particularly so in the far NE. Then as the Lo to the SW fills somewhat it still looks possible for it to be re-invigorated by another tongue of cold air moving SW from Norway and engaging in the Low pressures circulation to the SW and creating a resurgence of wet and unsettled conditions at times later next week. However, having said that ECM has moved away from this theme and splitting Low pressure to the SW and NE then with High pressure which would settled things down nicely next weekend. Other output too show the chance of lifting Low pressure towards the NW which would give rise to another route to rather better weather across the South and East with milder air in tow. So in summary while some improvements are shown today it needs all the jigsaw pieces to fall in the right places for it to verify and with still a lot of cool and unstable air around on the charts this morning we may well have to be patient for marked improvements in the overall pattern to develop. However, it is April and any sunshine will make all the difference to how things feel and while unsettled remains the nature of this morning's report it's not all doom and gloom and quite normal for this time in Spring  

Next Update Friday April 8th 2016 from 09:00 

[johnholmes]

1 hour ago, knocker said:

I think care should be taken whatever criteria one is using. But having said that as a means (no pun intended) of detecting future trends ( in the medium term) of the upper air pattern. IMO the proper use of the anomalies. NOAA, GFS and ecm, is as good as any and better than most. Used correctly, that is a conformity between the three, preferably over two or three days, whilst also keeping an eye on the very variable ops output. That is the case at the moment and although obviously this interpretation can still be incorrect I know of a no better guide. I am of course open to other suggestions that may be superior.

Yes care is certainly needed in any attempt to analyse any model of whatever duration. The anomaly charts are in my view the best available set of charts that we have free for giving a fair, even good, idea of the overall upper air pattern. As 'mean' charts they are much less susceptible to the changes we see in the 2x or 4x daily synoptic chart outputs. It is rare in my opinion that they are far out in the 6-10 or 8-14 day periods. That includes when they predict no change in the major pattern or when they predict a major pattern change. 

Over the past 7 or 8 years they give something like a 70% average correct pattern in the upper air which is far better than any of the major synoptic models. Very careful use, in conjunction with all other available data, will also point to the possibility of major storms, development of minor (in terms of the major pattern) surface features that can have important implications in surface weather.

Looking at the last few days of 500mb anomaly ouputs, especially the main 3 I use, and what continues to strike me is the relative coldness of the predicted 500mb flow and its origin. Over the winter it was not very often that the 500mb contours turning up over the south of the Uk had their origin from just south of Hudson Bay but this has been the case, as a mean, for some days now, and continues to show out to day 14 on the latest NOAA from last night, see links below. So no sign yet, other than an odd day now and then when the surface flow will give air from a much more southerly area, of major warmth occurring well out into April

http://www.cpc.noaa.gov/products/predictions/814day/500mb.php

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

Edited April 7, 2016 by johnholmes

[Nouska]

It is interesting that there is so much divergence between the different types of interpretation of the extended means. I suppose this reflects the fact that there are so many options among the ensemble members.

ESRL/PSD 

The other upstream analogue looks very different for day 11 and with such a negative AO, maybe using past climatology to create it is rather suspect.

 

[knocker]

The ecm 5-10 this morning is as expected but it should be noted that towards the end of the period it begins to rapidly erode the Greenland HP.

This process continues in the 10-15 period but it then also applies to the Atlantic trough the result being a zonal westerly flow with the continuation of the unsettled weather albeit with some drier interludes There are indications of some height rises to the east.

[knocker]

The colder air within the circulation of the low that has tracked down from Greenland.

[damianslaw]

Very quiet in this thread today, not sure why, the models are far from dull viewing, indeed quite a changeable synoptical pattern and very different to the default normal pattern, if this was even just a month ago I suspect it would be a fervour of activity, with prospects of low level snow if they came to fruition, alas we are just a bit too far into the year to expect notable cold or snowy weather (can't be ruled out though look at 1981 - not saying this will happen).

Back to the models, low pressure anchored to our SW going nowhere fast, with frontal/trough activity thrown northeastwards as we see a robust set of heights to our NW. Models show a more pronounced NE flow later next week with some very cold uppers not far from NE Scottish coast. Northerlies and easterlies galore - it must be April!

Edited April 7, 2016 by damianslaw

[knocker]

The NOAA 6-10 and ecm continue to sing from the same hymn sheet with high amplification in the Atlantic with the upper low to the SW of the UK. Ergo a continuation of the SW/S upper feed and some very varied weather and temps over a few days ranging from thundery showers, periods of more sustained rain and sunny intervals. Despite the variation in temps probably in general around average. Of course this kind of set up doesn't preclude systems moving through and creating very transitional northerlies/north easterlies.

NOAA in the 8-14 period continues to deamplify but does retain the weakening low pressure to the SW so no huge change in that repect so no imminent change to warmer conditions although it should warm up a tad more particularly in the south. The EPS 10-15 is not massively different but does tend the weakening  trough more mid Atlantic thus veering the flow somewhat. Similar story continuing unsettled but chances of drier and warmer weather in the south.

Edited April 7, 2016 by knocker

[knocker]

The latest EC32 means update - a brief look

On the 17th it is very similar to this

In the next four days it rapidly loses the trough to the SW of the UK and the ridging over eastern N. America and the pattern becomes flatter and zonal with a very weak trough over the UK. This zonality with troughs running west-east and HP away to the SW continues until the end of the month  In the first week of May there are signs of high pressure becoming more of a feature over the UK as the Azores HP pushes north.

So in a nutshell it looks very likely that the current pattern will break down around the 19th into a more zonal affair but the unsettled weather looks set to continue as systems run west-east bringing periods of wind and rain albeit with some drier periods and with temps quite variable but generally around average. By the beginning of May perhaps some drier and warmer weather but that's a long way off.

Back to the present - a complex area of low pressure?

 

Edited April 8, 2016 by knocker

[cyclonic happiness]

I feel sort of sad for the MOD thread this year.

 

There must be only two or three people who post on here over the past few weeks, less than ever. 

Just goes to show how lacking in true wither weather we've been down south, over the past 3 years.

Fingers crossed we have a thriving MOD thread this winter, and maybe even before that, this summer.

 

Anyway, just to tell you who still post regularly 'thank you' for your updates, I'm sure I can speak for everyone in stating my gratitude for your enthusiasm, even when the weather is being so bland 

[mb018538]

I think everyone is just a bit disenfranchised with things at the moment! It's just so distinctly bland and average that nobody can think of much to say. Nothing much has changed this morning in that the 7-10 day period will be dominated by low pressure anchored to the SW.

[knocker]

52 minutes ago, cyclonic happiness said:

I feel sort of sad for the MOD thread this year.

 

There must be only two or three people who post on here over the past few weeks, less than ever. 

Just goes to show how lacking in true wither weather we've been down south, over the past 3 years.

Fingers crossed we have a thriving MOD thread this winter, and maybe even before that, this summer.

 

Anyway, just to tell you who still post regularly 'thank you' for your updates, I'm sure I can speak for everyone in stating my gratitude for your enthusiasm, even when the weather is being so bland 

Interest in meteorology remains the same whatever the weather. Anyway there is nearly always something of interest. Such as the current cold plunge over eastern N. America. If that was happening over here there would probably have been 20 odd cardiac arrests by now.

Edited April 8, 2016 by knocker

[SteveB]

I also think most people are still reeling from the poor Winter, especially as the early signs suggested a bit of proper Winter weather towards the back end which never materialised.

At least the models aren't showing a washout.

Infact Sunday is looking like a nice day with some usable day's all next week as well, in-between some heavy thundery showers.

Edited April 8, 2016 by SteveB

[Gibby]

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS ISSUED AT 09:00 ON FRIDAY APR 8TH 2016

THE CURRENT GENERAL SITUATION A weak ridge of High pressure crossing East over the UK today will be followed by an occluded front moving NE across the UK tonight and tomorrow followed by a slack and showery cold flow over the South and West tomorrow in association with a deepening Low pressure area to the SW of the UK on Sunday.

http://www.wetterzentrale.de/pics/Rtavn001.gif

CURRENT SNOW FORECAST AND FREEZING LEVEL OVER THE UK The freezing level across the UK around 3500ft across the UK currently will rise briefly in association with a trough moving NE over the UK tonight. It then falls to as low as 1700ft over Southern and Western England and Wales for 24 hours or so before levels rise towards 5000ft+ early next week. There could be some snowfall over modest hills of the South and West tomorrow.

http://www.snow-forecast.com/maps/dynamic/uk

http://www.natice.noaa.gov/pub/ims/ims_gif/DATA/cursnow.gif

MODELS-2 WEEK HEADLINE Unsettled with showers or spells of rain with some brighter spells too especially over the North. Near average or slightly below average temperatures. Perhaps warmer later in the SE.

THE GFS JET STREAM FORECAST The Jet Stream is shown to maintain a trough or circulation to the South of  the UK over the next week to 10 days with the Jet flow realigning towards the North of the UK later in the second week.

http://www.netweather.tv/index.cgi?action=jetstream

GFS OPERATIONAL The GFS Operational Run today shows a lot of showery and unsettled weather across the UK over the next week as Low pressure to the SW remains in situ and extends in a belt across the UK at times delivering showers and longer spells of rain at times with temperatures recovering to nearer average in the South but remaining on the cool side over the North. then through the second week High pressure builds back over the UK from the NW settling things down to dry and fine weather for many although the positioning of the High on this run allows for a chilly Northerly flow to affect the East coast at times perhaps with the odd shower and frosts at night still look a real possibility under any clear skies by the end of the period.

GFS CONTROL RUN The GFS Control Run as yesterday is less optimistic surrounding improvements over Week 2 as Low pressure areas transfer to over or to the North and NE of the UK with cyclonic winds and a continuation of spells of rain and showers continuing for all out to the end of the run and it will remain largely cool too.

http://www.wetterzentrale.de/pics/Rtavn1441.gif

http://www.wetterzentrale.de/pics/Rtavn3841.gif

http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=144&mode=0&carte=0

http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=384&mode=0&carte=0

GFS ENSEMBLE DAY 14 DATA  The GFS Clusters today show almost complete Low pressure dominance across the UK in two weeks time with the positioning favouring Northern Britain with cool Atlantic West or NW winds bringing rain and showers at times for all. Of those members that show any deviation to this pattern are not offering anything better to be honest.

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 The UKMO model this morning shows a breezy and unsettled start to the new week with Low pressure always in close proximity. There will be spells of rain and showers for all in temperatures at best near average and rather cool in the NE flow on the Northern flank of the Low pressure belt across the UK by midweek.

http://www.wetterzentrale.de/pics/Rukm1441.gif

THE FAX CHARTS The Fax Charts show Low pressure setting up shop down to the SW of the UK over the weekend and start to next week with rain and showers at times, the showers most likely across the South and the longer spells of rain across Central parts as fronts stagnate with the driest weather but coolest conditions by then in the far North while some less cool conditions are likely to move into the South at times.

http://www.weathercharts.org/ukmomslp.htm#t120

GEM GEM today shows the synoptic pattern stuck in a rut once Low pressure develops close to the SW of the UK over the next few days, Throughout the period showers or longer spells of rain look likely almost everywhere and any when with some drier and brighter spells mixed in too and temperatures after a cool weekend could recover somewhat across the South with time.

http://www.wetterzentrale.de/pics/Rgem2401.gif

NAVGEM NAVGEM today also maintains a very unsettled outlook with Low pressure down to the SW remaining in control of the weather for the upcoming week weakening for a time midweek but reinvigorated again in time for next weekend and all the while maintaining at least the risk of rain and showers at times for most of the UK.

http://www.wetterzentrale.de/pics/Rnvg1681.gif

ECM ECM today continues illustrate similar synoptics to the rest of this morning's outputs with only tentative improvements hinted at towards the end of it's 10 day period. So Low pressure to the SW will extend across the UK at times with rain and showers at times with some brief drier periods too. Then at the very end of the period the link between Low pressure to the NE and SW is severed with a slack area of pressure developing meaning somewhat drier and warmer conditions look likely by the end of the run.

http://www.wetterzentrale.de/pics/Recm2401.gif

ECM 10 DAY MEAN (12z) The 240hr mean Chart from last night shows Low pressure painfully close to the West of the UK with cyclonic winds likely across the UK at 10 days with rain or thundery showers at times still the order of the likely conditions expected for most.

http://www.wetterzentrale.de/pics/Reem2401.gif

NOTABLE TRENDS & CHANGES FROM PREVIOUS RUNS A changeable and Low pressure driven period of weather for all is maintained from the models once more this morning. The trend towards yesterday's shown improvements has been somewhat muted again this morning with little change in the overall changeable and occasionally wet conditions.

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKMO & ECM The verification Statistics of GFS, UKMO and ECM show at 24 hours ECM ahead at 99.6 pts with UKMO at 99.5 pts and GFS at 99.4 pts.  At 3 days ECM is leading with 97.6 pts to UKMO's 97.2 pts while GFS lags behind at 96.0 pts. At 5 days ECM leads with 90.0 pts to UKMO at 88.4 pts and GFS at 85.1 pts. Then at 8 Days ECM has the leading spot from GFS with 65.7 pts to 60.5 pts. Finally at Day 10 ECM has the lead from GFS with a score of 44.9 pts to 41.0 pts.

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day1_PMSL_MSL_G2NHX.png

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.png

MY THOUGHTS  The models have shown a lot of consistency this week in maintaining their projection of Low pressure developing down to the SW of the UK this weekend and here we are at Friday and that is still the message shown by all output without exception. The problems arrive that once there how long will it remain there and how will we eventually break out of the pattern. I begun to think yesterday that the Low would eventually fill and allow higher pressure to gain more influence with warmer conditions given time and that message is still hinted at by some members of each model. However, there is also a lot of focus on a surge of cold air to flood SW over the Norwegian Sea next week  and getting caught up in the circulation of Low pressure close to or over the UK by then serving to deepen it again and strengthen the risk of further spells of wind, rain and showers. Of course day to day details on this pattern depends on how exactly it evolves but it does look like the next 10-14 days look fairly unsettled and cool with showers or longer spells of rain at times mixed in with some drier and brighter periods when in April sunshine it should not feel too bad. This type of pattern is not too untypical of April as the April showers saying is testament too and it does give the opportunity for some big shower clouds to grace our skies on occasion with the words 'hail and thunder' a part of the weather forecasts for the next week or so at least almost anywhere. Temperatures look like they might recover across the South given time but it does look like staying largely cool across the North throughout. So that's it from me for today, I will be taking a day off from the models tomorrow but will be back on Sunday morning for a roundup of what lies ahead for the next few weeks across the UK.   

Next Update Sunday April 10th 2016 from 09:00

[Ravelin]

I'd just like to re-iterate to the 'hardcore' who are still posting here that your efforts are appreciated. I for one still read through the thread most days.

My preference for cold winter weather is what really brought me here in the first place, and although undoubtedly not without interest, the current synoptics just don't raise any enthusiasm. Maybe as summer approaches the second best thing, the search for some warmth, will bring some life back to the thread.

I know if I want to learn I should be continuing to look at the models etc even now, but after a tough winter in that respect I've been enjoying not being that obsessed that I checked every model run.

[stodge]

Morning all

Martin, as usual, pretty much sums it up. It's a story of three parts in the near future.

1) An initial spell of rain and showers as the LP slides south just to the west of Ireland to set up shop in the SW Approaches.

2) A showery but possibly warmer interlude Monday-Tuesday especially for the south though the showers could, as Martin opines, be heavy, thundery and slow moving.

3) The trough re-invigorates via the feed of cooler air Wednesday-Friday and it's back to a cooler regimen with plenty of rain and showers likely.

After that, plenty of options on the table - it does seem as though the trough will dissipate leaving the cut off LP to the SW and the possibility of HP to the north ridging across the British Isles which would settle things down.

[knocker]

One advantage of the trough positioned as it is forecast is that it keeps the colder air to the SW and the UK in the south westerly flow.#

[knocker]

I think the METO take on this is slightly different

Chief Forecaster's Assessment

An area of Low Pressure is expected to deepen in the Southwest Approaches overnight Saturday into early Sunday morning, bringing strengthening south to southeasterly winds along with a band of persistent, and at times heavy rainfall. There is currently good confidence in the overall timing and location of the strengthening winds, but less certainty surrounding the location of the heaviest rainfall. Additionally, the strong winds coincide with high spring tides which will lead to some large waves and spray affecting coastal areas exposed to the south. This warning will be kept under review and updated as necessary in the light of new information.

[stodge]

24 minutes ago, knocker said:

One advantage of the trough positioned as it is forecast is that it keeps the colder air to the SW and the UK in the south westerly flow.#

The colder air is also to the NW and is held there by the LP but much of the model output brings the colder air back in through midweek. The above for the end of next week is one option among many on the table. Another possibility is pressure rises to the north of the cut off LP and ridges across the British Isles which would keep us settled but might not expose us to the warm SE'ly feed.

Another option is for the cut off LP to fill in situ and for a more zonal pattern to re-establish.

A third would see a pressure rise to the south and east and bring in warmer air but with still a potential for showers.

As someone once said somewhere, "more runs are needed"

[phil nw.]

It looks like we continue into the next week with the unsettled and often cool cyclonic weather with the usual April showers or rain bands.These feeding north and east around a slow moving low positioned around the south west approaches.

A look at 12z GFS at day 5 shows quite an elongated  upper trough heading south west from the Arctic ocean north of Norway right down towards Iberia with the UK within it's influence for quite some time.

The amplified ridge in mid-Atlantic forcing the last of the deep Arctic cold south into Canada and N.Scandinavia on either side.The final break up of the Polar vortex now getting underway as the cold pooling at higher latitudes starts to disperse and modify. 

 

 

[knocker]

The latest for Sunday.

For the rest of the week the GFS has the trough to the SW in control of things with the temps around average.but quite wet on Weds.

 

Edited April 8, 2016 by knocker

[Singularity]

I wouldn't say it looks cool next week - temperatures generally near or above average;

 

This occurring despite plenty of cloud and rain about - a reflection of the trough position W/SW of the UK coupled with enough of a ridge to the SE to keep us generally in tropical maritime airmasses as opposed to return polar maritime.

Roll things forward and after a temporary relaxation, the ridges comes back with a vengeance and encourages an import of warm air from the south - the extent open to debate; anything from nothing much to something noteworthy seems plausible.

Not many of the GEFS want to draw that early build of heat as far west as France and the UK, but I've seen these situations correct west when moving out of the 8-10 day range before (only to return some of the way back east again in the 2-3 day range!).

[Milhouse]

Southern England would benefit from the increasing warmth over the Channel if the ECM 240h chart verified. Big temperature variations here with possibly the first 20c in southern England but a nagging northeasterly pegging temps back further north. Nice to see the models flirting with the idea of something warmer and/or more settled.