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

[Winter Cold]

Its the GFS vs the others again. So much depends on that low it keeps showing pulling the warm air up but the 6z is once again well above the mean as I showed it was last night on the 12z also. The 0z run this morning was much more inline with the ensembles and had temps around mid teens for London which seems more likely and still obviously very nice in the growing signal for high pressure and sunny weather.

 

It could be a case of the GFS just teasing us again!

[Summer Sun]

GFS ens shows high pressure starting to build later next week

 

 

And it stays around till at least mid month

 

 

Very pleasant by day where its sunny but overnight temperatures would still be chilly with the risk of some frost in rural areas

[knocker]

Positive 850s can still give frosts, last week we saw 850s above 0C which still gave some quite widespread frosts across the UK, even down here in the south east.

 

 

What days were you thinking of Cs as I'm having a bit of trouble calculating how you get an air frost with positive 850mb temps at this time of year. If we are thinking radiative inversions that's some inversion. Grass mins can of course be much lower than the surface air temp.

 

For example taking an 850mb temp of plus 1C, using the ELR, the temp at the top of the inversion would be about plus 9C so that rules that out. Even reducing the lapse rate doesn't help much so I'm struggling here.

 

As mentioned the GM can be 5 or 6 degrees below the air temp so ground frosts are possible.

 

I'm taking subsidence inversions as being unlikely

Edited April 30, 2015 by knocker

[Frosty.]

The Gfs 12z is looking very good from later next week onwards with high pressure building in and settling our weather down, gradually warming up too, the high intensifies over the UK...Fantastic charts.

Edited April 30, 2015 by Frosty.

[Winter Cold]

Quiet in here this evening!

 

Well GFS still playing games tonight with the 12z once again far too enthusiastic. You can see here its pressure charts are far above the mean, and the 850s once again jump up which gives temps as the best case scenario:

 

   

 

 

Its like a dog with a bone though so we'll see!

 

Before all that though, next week looks very unsettled with rain and showers around with low pressure close by. The rise in pressure isnt showing until a week tomorrow so too far off to be sure at the moment, although GFS and ECM have been showing it. One to keep watching

[ANYWEATHER]

Quiet in here this evening!

 

Well GFS still playing games tonight with the 12z once again far too enthusiastic. You can see here its pressure charts are far above the mean, and the 850s once again jump up which gives temps as the best case scenario:

 

   

 

 

Its like a dog with a bone though so we'll see!

 

Before all that though, next week looks very unsettled with rain and showers around with low pressure close by. The rise in pressure isnt showing until a week tomorrow so too far off to be sure at the moment, although GFS and ECM have been showing it. One to keep watching

Indeed. The models were showing a pressure rise this time last week for this time and guess what happened.....

[Summer Sun]

ECM maintains a potential rise in pressure later next week

 

Edited April 30, 2015 by Summer Sun

[Frosty.]

The GEFS 12z mean shows strong support for high pressure to bring a warmer and settled spell to most of the UK from late next week onwards.

[Stuie]

Indeed. The models were showing a pressure rise this time last week for this time and guess what happened.....

 

I thought the models last week were showing snow to low levels this week?

 

Anyway. It looks like for the "Spanish plume" to happen this Atlantic LP system drops due South which propels the HP. For me that is way to far off to feel confident about.

[knocker]

Forget the "Spanish Plume" for the moment what the anomalies have been saying and what the GEFS is still saying tonight (haven't as yet seen the ECM but not expecting it to differ) is for the Atlantic trough to retrogress and and the Azores ridge to build. Confidence in this should be reasonable high.

Chart weatherbell

 

[Summer Sun]

A settled end to next week from the ECM ens

 

 

Pleasant enough by day but still the risk of frost in some rural areas where skies are clear

[johnholmes]

Looking at how the anomaly charts are moving over the past few days.

There does seem some evidence for a slacker 500mb flow; for this to be south of west into the UK

for there, on the NOAA 8-14 to be a small signal of a ridge in the UK area and for +ve heights to develop in the same area.

Not showing really on any of the 6-10 versions, NOAA, ECMWF, GFS but something to watch.

links as usual below

 

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

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

[bluearmy]

the cold and troughy cycle seems destined to end as we head through next week. will the return of high pressure be an interlude or a return to the pattern we saw through much of april ?

[knocker]

A look at the latest update from the EC32

 

Firstly the pattern change. Thursday the 7th has upper trough NW of the UK orientated south with LP over the Pole and NE Canada. Thus cyclonic W/NW over the UK with temps below average.

 

By the 9th the trough in the eastern Atlantic has gone to be replaced by the Azores ridge and also a build up of heights NE Europe. So HP over the UK and average temps.

 

By the 17th a more zonal flow with the HP to the SW but influencing the UK and a trough NE Canada. Temps around average.

 

By the 24th the HP still to the SW but more prominent ridging over the UK thus interrupting the zonal flow with a NW anticyclonic one and temps still around average.

 

The 1st of June and the scenario is similar.

 

Summary

 

Immediately after the proposed pattern change around the 8th (which has been around for a few days now) for about five days the ridge is in situ over the UK but still a strong trough south of Greenland so this will need watching but after that the the trough dissipates and the UK is under the influence of the HP to the SW. There is no sign of cyclonic development so the strength, or not, of the HP influence is the key to the evolution. Temps around average so without being memorable it could be a pleasant month after the next week.

[Captain Shortwave]

A bit of a mess pretty much sums up the output this morning. 

I guess a few things can be looked upon here.

Regarding Tuesday, an area of low pressure moves up from the Bay of Biscay, uncertainty on the track here but the risk of heavy and potentially thundery rain with very warm air wrapped around this. The ECM for example has this low moving up the western side of the UK.

We could see 850s of 10C in the east from that plume before it gets shunted off to the east, this could fuel some thunderstorms and possibly some warm temperatures if the sun comes out.

Beyond that the trend for high pressure to build seems to be getting squeezed by heights also building over Greenland, the jet is still aligned SW/NE but now with low pressure crossing further south, hence a wetter picture during the mid-range. ECM again used but the consensus is agreed this morning.

 

The ECM still builds the high in at day 9 (the day 10 chart is a beauty with temperatures into the 20s across the UK), but the GFS has really gone off the idea and keeps us in a changeable west/south west pattern into week 2.

Edited May 1, 2015 by Captain shortwave

[Frosty.]

The Ecm 00z turns into a thing of beauty by day 9 and especially day 10 with high pressure building north and intensifying, great to see the 564 dam extending north too. If the ecm or similar verifies, we will see temperatures heading towards the mid 20's celsius range and perhaps ultimately higher beyond T+240.

[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 FRIDAY MAY 1ST 2015.

 

THE CURRENT GENERAL SITUATION A ridge of High pressure will persist across Northern and Eastern Britain with a strengthening cool and strong Easterly flow across the SW with troughs further down to the SW edging NE later.

 

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

 

MODELS-2 WEEK HEADLINE Unsettled  at first with rain or showers. Perhaps becoming drier and warmer, at least for a time later.

 

THE GFS JET STREAM ENSEMBLE FORECAST The Jet Stream is currently blowing East over Southern England and France. In the coming days the Western end of the flow will dip further South still to set up a SW to NE flow from Spain to France to Europe where it is maintained for some time. Later in the run the flow realigns somewhat further North across the Atlantic to flow East across the UK later in the period.

 

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

 

GFS OPERATIONAL The GFS Operational this morning shows Low pressure and troughs moving North over and to the west of the UK over the coming days. Spells of rain followed by more showery weather will occur between now and the start of next week. Further troughs move in before midweek before a NW/SE split sets up with warmer drier weather over the South and East while the North and West see stronger SW winds with further rain at times. Then later in the run changeable conditions persist with alternating periods of fine and bright conditions with cloudier wetter ones for all areas.

 

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

 

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

 

THE GFS CONTROL The GFS Control run is equally changeable this morning with a similar rise in pressure to the SE for a time later next week with some fine and bright and warmer weather likely across the South and East at least for a time before Week 2 is shown to be largely Low pressure governed with some cool and wet weather likely for all at times in fresh breezes.

 

THE GFS CLUSTERS The GFS Clusters today show a 70/30 split in preference towards drier and settled conditions under a High pressure ridge near the South at Day 10 while 30% show a more changeable period with rain or showers under a trough of Atlantic Low pressure to the North.

 

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 this morning shows quite disturbed conditions across the UK with the slow progress North of complex Low pressure edging North over and to the West of Britain with sunshine and showers or longer spells of rain through the working days of next week in temperatures close to average offset by the Westerly breeze later.

 

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

 

THE FAX CHARTS The Fax Charts this morning show the Low pressure and trough complex moving North across the UK over the long weekend and the Fax Charts have now picked up on a new Low pressure area developing over Western France on Monday pushing further rain up across Southern Britain early next week

 

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

 

GEM GEM this morning shows slow improvements likely from the South later next week. Until then though a lot of rather cloudy and at times wet conditions look likely for many as a complex Low pressure area moves slowly North through the weekend and again at the start of next week before a ridge moves in from the SE next weekend with warmer and brighter weather at least for a time and more especially in the South and East.

 

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

 

NAVGEM NAVGEM shows Low pressure moving slowly North just to the West of the UK next week maintaining unsettled and showery conditions for many until the end of the week when pressure becomes slack across the UK fuelled by shallow disturbance moving up from the SW with further showers at times.

 

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

 

ECM ECM this morning maintains it's stance of recent runs with Low pressure being influential for much of next week before High pressure builds strongly across the UK with a lot of warmer air entrained by next weekend.

 

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

 

ECM 10 DAY MEAN(12z) The ECM 10 Day Mean Chart  from last night shows a strong ridge lying across the UK with fine and warm conditions likely to have developed for many by then.

 

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

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The models have reduced the longer term influence of High pressure in Week 2 of the period bar ECM who maintains it's stance of recent runs.

 

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 97.3 pts followed by UKM at 96.7 pts and GFS at 96.0. At 5 days ECM  leads UKMO with 88.4 over UKMO's 87.7 pts with GFS at 84.6. At 8 days ECM remains the leader with 59.9 pts over GFS's 57.0 pts. Then at Day 10 ECM retains superiority at 43.8 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 Today's output has changed on two themes which were not apparent yesterday. Firstly the pattern of the coming days remain unchanged with troughs moving NE across the UK over the weekend introducing rather warmer air with a mix of sunshine and showers following. Then the first change becomes a much more enhanced detail which will influence the weather next week as a new Low looks like developing over Western France on Monday becoming absorbed in the main Low complex to the west of the UK and delaying improvements next week as a more sustained Westerly feed establishes ahead of rising pressure eventually from the South late next week. This then leads me on to the second change this morning which away from the ECM output this morning show much less extent of higher pressure affecting anywhere other than the South and East of England next weekend and beyond before renewed Low pressure moves back in from the Atlantic across the UK through Week 2. ECM though continues to fly the flag for some fine and summery conditions developing across most parts of the UK from next weekend as High pressure is shown to sit across the UK by Day 10. Which is right is hard to call with all models offering some credibility but I'm hoping that the GFS is just overdoing the return of Low pressure in Week 2 and will redress the balance towards High pressure over up and coming runs. The Jet stream forecast from GFS is shown to remain quite well South though but ECM has it well away to the NW by Day 10 and I hope it's right as it flies a lonely flag in the 'sustained' fine weather camp this morning. Whichever way the dice falls it does look as though the risk of night frosts should gradually subside as we move deeper into the month as the cold uppers of late retreat slowly away back towards the Arctic.

 

Next update from 08:00 Saturday May 2nd 2015

[Summer Sun]

Changes from ECM this morning with it delaying the proposed rise in pressure

 

 

The same charts from yesterday's 12z showing the differences

 

 

The high does still move in as shown above but its not till day 9 now, just have to wait and see how this run sits with its ensemble

 

EDIT day 8 ENS chart shows the high coming in unlike the Op

 

Edited May 1, 2015 by Summer Sun

[picog]

Nothing especially settled suggested by the GFS ens. In fact, quite the opposite:

http://www.wetterzentrale.de/pics/MT8_London_ens.png

http://www.wetterzentrale.de/pics/MT8_Manchester_ens.png

[Frosty.]

The Gfs 6z through low res is generally much better than we have had for the last week or so, there is a lot of fine and pleasantly warm weather with high pressure in control for most of the time. Very warm air across the near continent flirts with the south later in FI.

The latest met office outlook (6-15 day) is very good news with warmer and more settled weather spreading from the southwest although there is a ? how far northeast the fine and warm weather gets but for southern UK things are looking up later next week onwards with the Azores high building NE into the uk

Edited May 1, 2015 by Frosty.

[NO LONGER POSTING]

Indeed. The models were showing a pressure rise this time last week for this time and guess what happened.....

 

The models also showed 2 weeks ago for this time back then that it would be cold this week and crap... Erm

[Frank Trough]

The models also showed 2 weeks ago for this time back then that it would be cold this week and crap... Erm

 

And pressure has risen, hasn't it? Hence the fall of pressure over the weekend:

 

 

The 06z ensembles fairly supportive of a pressure rise next week, at least in the south. We'll see - it still remains out t+120 and while it stays there it's not going to happen! 

[Summer Sun]

GFS is moving back towards a more settled outlook this afternoon with only the extreme north west at risk of some rain / showers from around Friday / Saturday

 

 

Temperatures respond accordingly easily getting into the low 20's for a lot of England and Wales

 

 

[Frosty.]

The Gfs 12z is the best gfs run so far today with the Azores high building in later next week and bringing most of the UK a prolonged warm and summery spell with lots of sunshine with temperatures into the 70's F. These charts are excellent and remind me of yesterday's 12z.

Edited May 1, 2015 by Frosty.

[Stuie]

Before we get to any hot-spots next Tuesday looks pretty dire.