Model Output Discussion - Spring 5th March Onwards 6z--->

[Gibby]

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 MONDAY APRIL 20TH 2015.

 

THE CURRENT GENERAL SITUATION High pressure will lie across Northern Britain with slack winds across all areas.

 

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

 

MODELS-2 WEEK HEADLINE A lot of dry, settled and occasionally warm weather across the UK at first before becoming much more unsettled with rain and showers at times later especially in the North.

 

THE GFS JET STREAM ENSEMBLE FORECAST The Jet flow remains weak and locataed well to the North of the UK. The flow rejuvenates later this week with the main arm developing to the South and then over the UK through next week gradually turning NW to SE across Britain later in Week 2.

 

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

 

GFS OPERATIONAL The GFS Operational this morning shows High pressure in control of the UK weather for the next few days before it declines by Friday as Low pressure moves up from the SW deepening to the North of the UK by the start of next week. The resultant windier and more changeable conditions will be well established by the end of the weekend leaving next week changeable for all with further rain or showers but some drier conditions too at times especially in the South. Late in the run a cold and unsettled Northerly or NW flow maintains the unpleasant conditions for many. 

 

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

 

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

 

THE GFS CONTROL The GFS Control Run also shows unsettled and cooler weather arriving in time for the weekend with rain and showers at times. The largely unsettled spell then looks like being maintained for the rest of the period though with some drier spells in the South for a time mid run.

 

THE GFS CLUSTERS The GFS clusters show a 50% split this morning between options of High pressure over the UK in 14 days time and Low pressure delivering unsettled and at times wet conditions. Due to this choice of options being so evenly spread no confidence can be given to any clustering this morning.

 

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 shows High pressure declining away by Friday with a daisy chain of Low pressure stretching from the SW approaches to the North of Scotland next weekend delivering showery rain for many. The final frame shows the trough clearing to the East with slowly improving conditions to SW Britain by the end of the weekend.

 

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

 

THE FAX CHARTS The Fax Charts continue to show High pressure in control over the UK through much of this week before a complex trough system moves slowly NE across the UK from Friday with showery rain at times by then.

 

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

 

GEM GEM this morning shows High pressure in control across Britain until Friday when pressure falls from both the SW and North arriving as a complex Low pressure system close to the North and later East of Britain through the latter stages of next weekend and next week. Pressure is also shown to ridge strongly North across the Atlantic at that time. The net result will be cool and sometimes windy weather under a NW airflow with rain or showers, wintry on Northern hills next week.

 

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

 

NAVGEM NAVGEM also shows a shift to cool and showery weather through the weekend and beginning of next week as winds settle to blow from between NW and North.

 

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

 

ECM ECM today shows falling pressure too from the SW and NW by the weekend with a weekend of showery rain at times for many. A drier interlude is then likely across Southern Britain early next week as High pressure builds towards Northern France but maintained unsettled weather in Westerly winds across the North are then shown to extend to all areas later next week with rain and showers in blustery West winds for all in avearge temperatures by then.

 

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

 

ECM 10 DAY MEAN(12z) The ECM 10 Day Mean Chart  from last night looks likely to bring the UK largely cyclonic conditions later next week with Low pressure to the North affecting all areas in Westerly winds with rain at times and near to average temperatures for the time of year.

 

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

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trends this morning remain focused towards a much more unsettled spell developing from later next week with Low pressure much more influential for all.

 

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKM & ECM The current verification statistics for the past 31 days shows ECM leading the way at 3 days with 97.5 pts followed by UKM at 96.9 pts and GFS at 96.2. At 5 days ECM  continues to lead the field at 89.0 pts over UKMO at 88.3 pts and GFS at 86.1. At 8 days ECM remains the leader with 62.9 pts over GFS's 57.9 pts. Then at Day 10 ECM retains superiority at 44.4 pts over GFS at 41.9. 

 

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 The trend towards a more unsettled and possibly cool period is still very much alive this morning probably commencing from later on Thursday. The change will be a complex and unstructured affair with some places likely to see very little rain while others see rather more as much of the rain falls in showers which by nature are always hit and miss. Whichever way I look at it this morning there seems to be good agreement for Low pressure to lie up to the North of the UK early next week with cool and showery West or NW winds across Britain bringing further rain and showers. However, some Southern areas may remain largely fine for a time early next week as pressure to the South rises temporarily before we all settle down to a spell of Westerly winds with rain and showers with as ususal the heaviest rain and strongest breezes likely over the North and West. There are a few cold Northerly incursions in the mix too for later next week though this hasn't got universal support least of all from ECM who maintain milder Westerly winds across Britain. So enjoy the fine weather of the next few days as the downhill slide in conditions commences from late Thursday. Having said all that the weather looks far from a washout and looks nothing other than a traditional mid Spring unsettled spell when some welcome rainfall is coupled with drier and brighter days with some sunshine in strong Westerly winds at times.

 

Next update from 08:00 Tuesday April 21st 2015

[Summer Sun]

A few changes from ECM this morning by day 8 with a drier interlude for the south with a ridge of high pressure edging up from the south

 

 

Day 9 and 10 see unsettled weather returning but temperatures by this time would be recovering as we gain more of a westerly flow

 

[Captain Shortwave]

Day 6 charts

GFS

Cyclonic and cool with showers or longer spells of rain

 

UKMO

Cool and showery PM flow, a weak ridge of high pressure looks set to move in with a trough developing in the Eastern Atlantic.

 

ECM

Deeper trough through the UK, so similar surface conditions in terms of rainfall, but possibly a tad cooler with showers wintry over modest levels in the north.

 

GEM

Cyclonic north westerly, the model proceeds to bring a fairly prolonged cooler spell with high pressure building strongly in the Atlantic.

 

Still some uncertainty about how things develop beyond the coming weekend, though there are a few less cold runs starting to appear now. All of them do show a lot less settled conditions compared to what we have experienced for most of April so far.

[Summer Sun]

Looking at the ensemble for London the peak of the lowest pressure is the 26th after this the GEFS mean rises and hovers around the 1015mb area from the 28th till the end of its run (May 5th)

 

[mushymanrob]

The last sets of anomaly charts support lower than usual temperatures and fairly unsettled as well although the 8-15 does, as it usually does, tend to modify this a little.

Details of how cold, how unsettled will come as the T+00 gets closer from the synoptic models.

links to anomalies

 

http://www.cpc.noaa.gov/products/predictions/814day/814day.03.gif

 

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

 

ive noticed that the anomaly charts arent really supporting a mid atlantic ridge and a long draw of cold northerlies that some runs are suggesting. but a draw indirectly of cold air with unsettled conditions does look likely to see april out and may in.

[Frosty.]

The Gfs 6z shows rain spreading northeastwards across the UK during friday and the weekend looks cool and unsettled, cold enough for wintry showers on hills in scotland, for many of us it's a sunshine and showers weekend, some heavy with a risk of thunder. The chilly unsettled spell continues for the first half of next week but the showers gradually die out with more in the way of sunshine but with cold frosty nights but the second half of next week looks better with higher pressure and good spells of sunshine with daytime temps recovering to pleasantly warm levels, however, the 6z then shows another low swinging down from the northwest with a cold blast in its wake bringing a return of chilly, showery weather, the showers wintry on hills and further night frosts.

[knocker]

ive noticed that the anomaly charts arent really supporting a mid atlantic ridge and a long draw of cold northerlies that some runs are suggesting. but a draw indirectly of cold air with unsettled conditions does look likely to see april out and may in.

 

For a while the GEFs was hinting at a ridge nearer the UK but at the moment it's given up on that idea and at T240 we still in a quite cold airmass.

Chart weatherbell

[johnholmes]

ive noticed that the anomaly charts arent really supporting a mid atlantic ridge and a long draw of cold northerlies that some runs are suggesting. but a draw indirectly of cold air with unsettled conditions does look likely to see april out and may in.

 

True enough especially on the 8-14 which almost always has a tendency even when following the 6-10 of 'watering' down its version. The 6-10 neither has any mid Atlantic ridge but a very marked trough with the 500mb flow (for northern areas) from Greenland and for southern areas a much longer sea track, via a trough off the eastern US seaboard from the Alaska region). All in all heights for the far south are suggested at about 550dm, so not warm and probably quite chilly especially for northern parts. Well that is my summary of how they have developed this scenario over the past 4-6 days.

By this time next week we will all know how cold and how wet and how far down any mountain/hillside it is white!

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

Edited April 20, 2015 by johnholmes

[Andy Bown]

The Gfs 6z shows rain spreading northeastwards across the UK during friday and the weekend looks cool and unsettled, cold enough for wintry showers on hills in scotland, for many of us it's a sunshine and showers weekend, some heavy with a risk of thunder. The chilly unsettled spell continues for the first half of next week but the showers gradually die out with more in the way of sunshine but with cold frosty nights but the second half of next week looks better with higher pressure and good spells of sunshine with daytime temps recovering to pleasantly warm levels, however, the 6z then shows another low swinging down from the northwest with a cold blast in its wake bringing a return of chilly, showery weather, the showers wintry on hills and further night frosts.

Thanks for all your posts of the various charts etc Frosty. Do you think Saturday/Sunday will have a slack LOW over the country with sunny starts then showers developing by lunch time? Or a more active LOW including bouts of wet/windy conditions?

[Frosty.]

Thanks for all your posts of the various charts etc Frosty. Do you think Saturday/Sunday will have a slack LOW over the country with sunny starts then showers developing by lunch time? Or a more active LOW including bouts of wet/windy conditions?

Hi Andy, thank you. Currently I'm thinking more a slacker LOW than a deep one for the weekend with early sunshine on saturday giving way to showers after the persistent rain clears through the UK by Friday night but I also think it could be breezy and the showers next weekend could merge into longer spells of rain, some heavy with hail and thunder but there are likely to be a few areas which miss most of the showery rain and have pleasant sunny spells, however, it is likely to become significantly cooler by Saturday, more so further northwest, it could even become cold enough for wintry ppn on northern hills, especially scotland and night frosts risk becomes higher.

Edited April 20, 2015 by Frosty.

[Captain Shortwave]

Day 6 charts

UKMO

Weak ridge building in again with the trough developing in the eastern Atlantic

 

GFS

Different with the ridge holding in the Atlantic allowing cold air to sweep southwards.

 

GEM

Quite similar to the GFS

 

So the stand off continues, beyond day 6 the UKMO would probably not be as cool and unsettled as the GFS/GEM.

[Frosty.]

The Gfs 12z turns into an unseasonably cold run for the time of year and also much more unsettled than we have got used to, a pattern change is on the way. Friday is the transition day with a band of rain spreading north and east. Saturday shows a risk of heavy, thundery showers but temperatures still look respectable in the south of the UK, cooler further north, colder by Sunday but the south of the uk looks drier and brighter but then through next week it looks very unsettled and chilly everywhere with a polar/arctic maritime airflow bringing sunshine and frequent showers, some wintry with hail and thunder, and bouts of heavy rain and strong winds with snow on northern hills, daytime maxima on some days struggling to reach double digits celsius in the south and lower than that further north. There would also be a high risk of damaging frosts for gardeners and growers if something like this run verified, snow in early may on this run.

Edited April 20, 2015 by Frosty.

[stodge]

Or you could argue the pressure distribution produces the NAO. Cart and horse?

Not at all - unlike the chopping and changing of the 6-hourly GFS output or 12-hourly output of the others, the NAO index has been showing a consistent swing towards negative since around Easter when I made mention of it. The significant aspect of the pattern change is the first significant negative NAO for many months and while that can manifest itself synoptically in a number of ways, it usually means LP to the SW and HP to the NW because that's where and how the pressure anomalies are measured.

 

The signal for a reversal of the "normal" pattern has been solid for nearly three weeks.

 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.mrf.obs.gif

 

Just going negative now for the first time since the turn of the year.

 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.sprd2.gif

 

Not much change with the lowest index recordings later this month and a noticeable recovery back to neutrality at the beginning of May so this doesn't look like a long-duration shift at this time.

 

http://modeles.meteociel.fr/modeles/gfs/runs/2015042012/gfsnh-0-90.png?12

 

There you go...

 

The push of HP south from Greenland re-creates the Azores HP and returns the anomaly to neutrality as pressure falls away over Greenland as shown:

 

http://modeles.meteociel.fr/modeles/gfs/runs/2015042012/gfsnh-0-198.png?12

 

ECM shows a west-based negative NAO for the end of the week:

 

http://www.meteociel.fr/modeles/ecmwf/runs/2015042012/ECH1-96.GIF?20-0

 

So not too bad over the British Isles. The problem is as the heights rise again to the south-west, the LP is dragged down from the north in the unstable air so we get this interesting one:

 

http://www.meteociel.fr/modeles/ecmwf/runs/2015042012/ECH1-216.GIF?20-0

 

Really interesting synoptic period approaching whatever the surface conditions after a frankly anodyne period.

[Winter Cold]

Some great charts showing up now for action weather fans like myself. Its a huge turn around coming up after a fairly non descript few weeks. Will be interesting to see just how cool/cold a northerly flow will be.

 

                                                     

 

 

 

The GFS 12z is actualy fairly well supported within the ensembles, it isnt an outlier or extreme solution:

 

 

Temps just 5 or 6c on the 28th here for South Yorkshire, amazing really. After that then struggling to get into double figures for the rest of the run!

 

 

Its as if we get transported to another planet on the 24th, from flat line to big rain spikes:

 

[ANYWEATHER]

Evening folks. The models show a decent breakdown by the end of the week with low pressure in control with just about every type of weather you could hope for!!!  Gfs , shows a cold shot of air across the nation late weekend , so with unstable air across the nation, cold air aloft and strong sunshine that equals for tall clouds to form and the recipe for some thunderstorms to develop along with some photogenic skies , That's not happened very much this month, So the good news April Showers are back , some big ones, Heres hoping!!!

[Summer Sun]

Some welcome rain for the gardens from the end of this week though for large parts of England and Wales totals don't exceed 20mm (out to day 10 the furthest this chart goes) the exceptions to this are western parts and northern England

 

 

The next thing we'll be hearing is talk about droughts......

Edited April 20, 2015 by Summer Sun

[draztik]

the anomaly charts being issued by ecm/ens are quite striking; strong negative anomaly in heights and temp for the UK into the mid term, with no let up post Friday out to 360.., /weatherbell.

 

we knew it was coming, but this will be quite a shock. Of course, it may change. But the ens are resolute in brining about a major pattern change into the weekend.

 

GEFS temp anom out to day 16. In broad agreement with what ecm ens showing.

Edited April 20, 2015 by draztik

[knocker]

A brief look at the latest EC32 output.

 

On the 30th Upper trough North Sea and Azores ridge to SW. still the blocking HP N. Canada and LP Eastern Seaboard. But the upper trough shifts west during the week until the 7th May. So the surface analysis has a succession of lows nipping across from the eastern seaboard bringing unstable conditions to the UK with the airflow between SW/NW and temps below average for the week.

 

The following week sees a gradual weakening of this LP dominate scenario with the Azores HP becoming more prominent and temps back to normal.

 

Between the 14th and 22nd this more stable state of affairs continues with ridging from the HP to the SW and heights inclined to rise in NW Europe. Temps a shade above average.

 

Summary.

 

From the 24th to around the 7th May mainly cyclonic conditions prevailing over the UK with temps below average and a number of wet and windy interludes. Thereafter conditions settle down somewhat with ridging from the SW and temps average or above but more unsettled weather cannot be excluded at times in the north.

 

And to set the scene so to speak the GFS this morning is running with a complicated scenario which I think requires some liberal doses of Saxo. It has a split low scenario for Saturday with one over Scotland  and the other SW of Cornwall. This evolves in the northern low moving to the north N. Sea and deepening before moving south and bringing some very windy conditions to the east coast.and before that Scotland.

Chart weatherbell

 

Edited April 21, 2015 by knocker

[Polar Maritime]

Yes Knock some pretty stormy/wet/windy conditions Model'd for the North around the 28th, A bitter wind chill and Snow down to modest levels with blizzard conditions in the Highlands. A very active end to the Month, Much different than the start..

 

Edited April 21, 2015 by Polar Maritime

[knocker]

It should be noted though PM that the ECM isn't going along with the GFS take on this and keeps the low to the north and doesn't run it down the North Sea.

[Polar Maritime]

Yes Knock, A pretty complex set-up as you say. With many more fine adjustments expected in the next few days, It will be very interesting how the Model's handle this as we get closer.

Edited April 21, 2015 by Polar Maritime

[Captain Shortwave]

Quite persistent troughing over the UK from the models this morning, showers and longer spells of rain with below average temperatures likely. That said snow away from the tops of the Scottish mountains probably won't happen. 850s tend to mix out as they head south with generally the -6C isotherm being the coldest we get and that is in the north.

[Frosty.]

I don't think snow would be confined to the tops of the Scottish mountains, the Gfs 0z for example shows a risk of wet snow even across southern Britain at times. It looks like a very unsettled and unseasonably cold outlook with polar maritime and arctic winds heading our way.

[Gibby]

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 TUESDAY APRIL 21ST 2015.

 

THE CURRENT GENERAL SITUATION High pressure will continue to be slow moving over the North of the UK with light winds for all.

 

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

 

MODELS-2 WEEK HEADLINE Becoming unsettled and rather cold with bright spells and showers, heavy and wintry on hills. Local night frosts still likely.

 

THE GFS JET STREAM ENSEMBLE FORECAST The Northern arm of the jet will weaken over the coming days as it moves slowly South towards the British Isles. The Southern arm will become the more dominant feature located over Spain before moving North to join the Northern arm over the UK later in the period where it remains in situ with it's orientation shifting to more NW to SE axis. 

 

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

 

GFS OPERATIONAL The GFS Operational this morning shows High pressure declining over the coming days with Low pressure edging up from the SW and deepening to the North of Scotland over the weekend and start to next week with rain and showers for all. A changeable pattern is then shown for the remainder of the period though with High pressure never far away from the South or West of Britain some Southern and Western areas may not see too much rain after the innitial period. Winds look like settling NW or even North at times so it will probably feel rather cool at times.

 

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

 

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

 

THE GFS CONTROL The GFS Control Run though similar for much of the run shows small differences but still has the underlying message that with High pressure close to the South and SW at times the most changeable conditions remain towards northern Britain with longer drier spells in the South. This run too shows rather cool conditions under NW winds at times.

 

THE GFS CLUSTERS The GFS clusters continue to show a variety of options in condiions by the end of the two week period ranging from a greater bias supporting the operational and control runs of High pressure most likely to the West and SW with West or NW winds and occasional rain the order of the days. The lesser options show Low pressure to the East and well out into the NW Atlantic with a contrasting North flow or milder SW flow so take your pick.

 

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 shows High pressure declining and being replaced by cyclonic conditions at the weekend with outbreaks of rain or heavy showers for all in cooler conditions overall as Low pressure settles to the North and NE of Britain.

 

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

 

THE FAX CHARTS The Fax Charts mimic the operational run of UKMO today with a decline in conditions from the SW on Friday setting up the weekend with a trough across the UK continung the risk of rain or heavy showers at times in progressively cooler conditions.

 

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

 

GEM GEM this morning is one of the coldest and most showery of the outputs this morning with Low pressure developing and becoming anchored to the NE of the UK with a cold and showery North to NW airflow lasting much of next week delivering heavy and wintry showers at times across the UK with some night frost later.

 

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

 

NAVGEM NAVGEM also brings cold NW and Northerly winds down across the UK in association with Low pressure anchoring across NW Europe and the North Sea at the weekend and start to next week with rain and showers in cool conditions and no doubt some wintry showers at times over the hills.

 

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

 

ECM ECM too challenges GEM for the coldest mantle this morning as it's run produces Low pressure sluggishly centred on the North Sea and Scandinavia next week feeding cold air down over the UK from the Arctic with plenty of convective and heavy showers all days across the UK with snow on the hills and patchy night frosts where skies clear.

 

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

 

ECM 10 DAY MEAN(12z) The ECM 10 Day Mean Chart from last night supports the operational well so I expect little change from this chart to the one produced later this morning with a cold and showery NW or North flow looking likely over the UK in 10 days time.

 

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

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trends this morning remain focused towards a much more unsettled spell developing from later this week though there are a few scenarios drifting towards higher pressure possibly developing closer in to the South and West at times.

 

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKM & ECM The current verification statistics for the past 31 days shows ECM leading the way at 3 days with 97.4 pts followed by UKM at 96.9 pts and GFS at 96.1. At 5 days ECM  continues to lead the field at 89.1 pts over UKMO at 88.4 pts and GFS at 86.0. At 8 days ECM remains the leader with 62.7 pts over GFS's 57.6 pts. Then at Day 10 ECM retains superiority at 44.4 pts over GFS at 41.1. 

 

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 The last days of fine warm conditions are underway this morning and it looks increasingly like we better make the most of them because from Friday onward it may be some while before temperatures return to the levels currently being experienced across the UK. All models have now underlined the change from Friday as our old friend High pressure declines away and is replaced by deepening Low pressure moving up from the SW towards a point North of Scotland by the end of the weekend. While the weekend itself may still feel pleasant enough in any sunshine between the showers it's as winds swing NW or even North early next week that cold air floods South and sets up what looks like being quite a long period when days will be characterized by bright periods and highly convective conditions with heavy showers delivering a cocktail of rain, hail sleet, snow and thunder coupled with frosts at night as skies stay clear. I would even go as far as to say that anywhere could see a surprise snowfall next week in the heaviest showers and before anyone says that it's too late in the season for that I can say with experience it has happened this late before and could happen again under some of the models synoptics this morning. However, despite the talk of this on the flip side of the coin strong late April sunshine between the showers could feel very pleasant still but frosts at night in this setup look inevitable for some and will prove very unwelcome if some of this morning's charts verify. So a real shock to the system looks likely across the UK this weekend and next week as summer clothes can be put back in the drawer for a time with warm coats and umbrellas becoming much more an accessory when out and about soon.

 

Next update from 08:00 Wednesday April 22nd 2015

[seaside 60]

I have to say that I know you guys are only reporting on what the models churn out.

However but surely this type of scenario has been progged so many times and every time its no where near as bad/cold by the time it gets here.

Also for the south east and east coast dwellers it may not be any colder after the last few days of fresh easterlies, I know today/tomorrow much warmer here but its been dam perishing.