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

[Milhouse]

Towards the end of the week a more pronounced area of high pressure starts to build up from the south.

 

[Frosty.]

The EC32 has been pushing this for a while.

Yes but it's the first time the MO have mentioned it, I've been reading the updates every afternoon and before today it's been saying below average temps until late May on their updates but mogreps must also be looking good for a warmer and drier mid may.

[Milhouse]

The GFS turns into a sublime run

 

[Summer Sun]

The heat builds in towards the end of GFS could quite easily hit 28c for some parts of the south meanwhile in northern Scotland some parts struggle getting above 10c

 

 

Before that it starts to settle down later next week just in time for the Malvern Spring festival which takes place from the 7th to 10th

 

 

Temperatures getting back to above average for most

 

[Frosty.]

The Gfs 12z in low res turns into a dream run with temperatures soaring into the mid to upper 20's celsius at times, these are beautiful charts to be sure.

[Frosty.]

The GEFS 12z mean shows a big improvement as we head further into May with a warmer and more settled further outlook with increasing high pressure influence, this looks really good to me.

Edited April 29, 2015 by Frosty.

[Winter Cold]

No surprise to see the GFS 12z being pretty much an outlier with temperatures and especialy 850s. Well above the mean which keeps things more sensible at mid teens level out towards the end for London for example:

 

   

 

 

[summer blizzard]

Euro less gung ho but agrees with the general idea. Probably closer to the truth..

 

[JoeShmoe]

The Gfs 12z in low res turns into a dream run with temperatures soaring into the mid to upper 20's celsius at times, these are beautiful charts to be sure.

 

Those are mouth-watering charts and look like the perfect early summer

[Frosty.]

Tonight's Ecm 12z shows the Azores high building in bringing warmer and increasingly settled weather to the south by the end of next week and I am guessing beyond T+240 would bring an anticyclonic spell to most of the UK.

[Craigers]

The UKMO turning things drier and warmer as we head into next week.

The eastern half of the UK could eek out a decent if brief southerly from this. Trouble is the uncertainty on the placement and orientation of the trough.

 

The GFS keeps things pretty unsettled with the trough closer to the UK. Though the south east does potentially catch some thundery rain from the continent.

The GFS in particular does't seem to be sure how the Atlantic profile will sit considering it has had Atlantic heights over the past few runs, ditched this time.

Typically low resolution produces potential 30C charts

Is there a chance UKMO is onto somthing showing a more southerly flow next Monday?

[Captain Shortwave]

No surprise to see the GFS 12z being pretty much an outlier with temperatures and especialy 850s. Well above the mean which keeps things more sensible at mid teens level out towards the end for London for example:

 

gefs29temp.jpg    gefs29uppers.jpg

Scatter developing from around the 5th, some warm runs around that point that support the UKMO evolution. No point worrying about that whopping GFS low resolution outlier

The models don't agree with each other at day 5/6, the GEM agrees with the ECM to a degree though.

 

If these are right then there could be a lot of rain from that Biscay low.

More runs needed as per usual, though the models are keen on conditions drying up during week 2, which is around the time when the long rangers were suggesting a more settled spell (towards mid-month).

 

@Craigers - looking at the ensembles Wintercold posted, there are some very warm members (going by the 850s) which show a sharper Atlantic trough like the UKMO and hence develop a southerly. The 2m temperature predictions are useless though.

Edited April 29, 2015 by Captain shortwave

[ANYWEATHER]

An unsettled spell of weather and rather chilly for the bank holiday weekend with welcome rain for the gardens if nothing else.....At day 7 still unsettled and cool, but by day ten, pressure trying to rise from the south, this is big time FI so folks don't get to carried away with this scenario , this will change!  after all its the UK!!!

Edited April 29, 2015 by ANYWEATHER

[Stuie]

An unsettled spell of weather and rather chilly for the bank holiday weekend with welcome rain for the gardens if nothing else.....At day 7 still unsettled and cool, but by day ten, pressure trying to rise from the south, this is big time FI so folks don't get to carried away with this scenario , this will change!

 

At least frosts shouldn`t be a concern.

[Winter Cold]

At least frosts shouldn`t be a concern.

 

I was just thinking do positive uppers definately prevent frost though? If it was December for example with +2 850s then youd probably get an inversion and then a ground frost at cold surface level. Even though its going on May now, weve seen that the ~-4 point this week has brought some very cold nights. Just wondering if a few degrees positive 850s at this time of year are enough? Always learning on here

[Stuie]

I was just thinking do positive uppers definately prevent frost though? If it was December for example with +2 850s then youd probably get an inversion and then a ground frost at cold surface level. Even though its going on May now, weve seen that the ~-4 point this week has brought some very cold nights. Just wondering if a few degrees positive 850s at this time of year are enough? Always learning on here

Good question and no answer. What also is in question is the time of my chart but no other time available. I`m going with the 0> positive uppers as maybe 3 degs minima.

[Captain Shortwave]

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.

 

ECM ens looking decent for week 2

 

Quite a decent signal for high pressure to build in during this timeframe. All can change though.

Edited April 29, 2015 by Captain shortwave

[Summer Sun]

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.

 

ECM ens looking decent for week 2

 

Quite a decent signal for high pressure to build in during this timeframe. All can change though.

 

GFS looks promising as well

 

 

The beebs latest week ahead forecast is suggesting the high could build more for the SE but great uncertainty at this range as to be expected

[Stuie]

The GEM going for it also. Those Greenland heights are going nowhere fast either.

[knocker]

Last evening's anomalies still looking at the transition around the 8th with the trough retrogressing  and the Azores HP becoming the main player. Slightly more emphasis on this from the ECM but with both the end result is the same.

 

In the ext. period both the GEFs and ECM have the HP in situ out to T360.

Charts courtesy weatherbell

 

[BlueHedgehog074]

Looking at the 8 to 14 day 500mb anomaly chart from NOAA (issued 29th April) and suggests a settled spell could develop over, and to the East of, the UK with a wedge of higher than average heights over the British Isles, especially to our South. The dip in the 500mb flow and the lower than average heights in the Atlantic suggests some troughing in that area. With a 500mb flow from the South-West this could allow some warmer air to get pumped further Northwards/North-Eastwards towards the UK on the Eastern flanks of the troughs/lows. This seems like a bit of a step up for those after something less unsettled as it was about a day or two ago this anomaly chart had the UK more influenced by Atlantic troughing to our West. (Though usual caution needed as always as it could still switch back to that idea).

As an example, though, models such as the GFS do seem to fit along with the NOAA's height rise ideas a fair way into its run.

The ECMWF does also try to build High Pressure over the Southern UK towards the end of its run. Some positive steps there if you're still wanting a more settled (and possibly warmer) spell and hopefully a direction the anomaly/models will keep going in.

With all of this concentrated in FI, then not worth taking too literally at the moment, although is nice to see some possible trends towards those possible height rises.

Edited April 30, 2015 by DiagonalRedLine

[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 THURSDAY APRIL 30TH 2015.

 

THE CURRENT GENERAL SITUATION A weak ridge of High pressure will develop across the UK today and tomorrow with weak troughs edging into the English channel from the SSW.

 

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

 

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

 

THE GFS JET STREAM ENSEMBLE FORECAST The Jet Stream is currently blowing East over 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 across the Atlantic to a more direct West to East flow still further South than is ideal for the UK in the second week.

 

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

 

GFS OPERATIONAL The GFS Operational this morning continues to show a very changeable period over the coming two weeks. The cold feeling weather at present will move away North behind a front moving North across the weekend and then the UK settles into a changeable pattern with all areas seeing at least a little rain at times under various mostly shallow Low pressure areas crossing the UK from the West. High pressure does feature through the middle of the run moving up from the SW giving several days of fine and settled weather before unsettled conditions return from the West again later.

 

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

 

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

 

THE GFS CONTROL The GFS Control run is broadly similar with the changeable pattern with the same rise of pressure shown through the middle of the run. Temperatures will be average or somewhat below at times under the cloudier and rainier periods with the emphasis on the drier air focusing perhaps on the North late in the run.

 

THE GFS CLUSTERS The GFS Clusters today show a 60/40 split in preference towards drier and settled conditions under High pressure near the South or across the UK at Day 10 while 40% show a more changeable period with rain or showers.

 

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 Low pressure deepening and moving North to the West of the UK over the long weekend with fronts moving North over all areas giving rain and followed by a blustery but less cool West or SW flow with heavy showers.

 

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

 

THE FAX CHARTS The Fax Charts mirror the raw data well with the ridge at the start of the period declining in the wake of Low pressure and fronts moving up from the South through the weekend and leaving a legacy of less cold and very unstable air at the start of next week..

 

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

 

GEM GEM this morning shows the same Low pressure and sequence of events that UKMO shows with Low pressure near NW Britain at the start of next week with very showery air over the UK. High pressure then builds from the South later next week with pressure becoming slack across the UK with just intermittent outbreaks of rain here and there by then from shallow Low pressure towards the South of the UK.

 

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

 

NAVGEM NAVGEM shows Low pressure to the NW in control too at the start of next week with a slow filling of the Low and a slow rise of pressure from the South though some showers on this run will last through to the end of the run 1 week from now.

 

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

 

ECM ECM this morning shows the same theme of Low pressure to move North just to the West of the UK taking it's troughs North over the UK over the weekend and following behind will be a showery Westerly or SW flow in milder air. This run is in no hurry to rise pressure from the South but it does eventually settting up much warmer and settled conditions across Southern Britain in 10 days time.

 

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 North 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 There is a better trend towards High pressure building from the South later next week and lasting into Week 2.

 

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 The models have firmed up on the likely course of events across the UK over the coming 10 days or so with just the usual divergence between the longer term output arising then for the end of the period. The current cool air across the UK and scattered showers will decay away later today as pressure builds from the North with a likely frost for many tonight. Weak troughs to the South will graze Southern England tomorrow before receding away South for a time giving a cloudier day tomorrow perhaps with a splash of rain here and there while the North stays dry and fine. Then over Saturday a more meaningful push North of troughs to the South coupled with a deepening low to the SW will move North as a complex structure with cool and rainy weather moving North across England and Wales on Saturday and Sunday and Scotland by Monday. Following on behind will be a switch of winds to the SW or West with milder air delivering heavy showers and some warm sunshine in places. Then as we move through next week the focus of showers will become more and more restricted to NW areas as the Low fills and pressure rises from the South. By next weekend it looks like High pressure will be getting a stranglehold on conditions across England and Wales and possibly Scotland too with the following week looking set fair and possibly warm for many with the usual caveats of Low pressure spoiling the party from some of the longer term output members. So all in all a period of changeable weather to come with temperatures on the rise next week with a mix of sunshine and showers following rain. Then at least if the ECM model is to be believed things could begin to turn quite summery in a week or so time with the other models showing a weaker form of a more settled theme at least for a time.

 

Next update from 08:00 Friday May 1st 2015

[Summer Sun]

Out of all the models its ECM which is going for the strongest high later next week, I can see temperatures back into the low 20's especially in the south during next weekend if something like below comes off

 

[Milhouse]

GFS 6z once again throws in a superb Spanish Plume. 30c would be quite likely if this came off. Sadly it is FI

 

 

[summer blizzard]

Fairly good agreement now that high pressure is back by day 9/10.