Model Output Discussion 31/03/14 onwards.

[Gibby]

HERE IS THE LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM TODAY MONDAY 12TH MAY 2014.

 

THE CURRENT GENERAL SITUATION. Low pressure will continue to move away NE over the North Sea with a showery but weakening Westerly flow across the UK veering NNW tomorrow as High pressure approaches from the WSW.

 

GFS The GFS Ensemble pack today show that after the improvements of later this week the weather turns unsettled and cooler again as Low pressure slips down across the UK and becomes slow moving. Cyclonic winds will deliver rain and showers for all at times with a slow trend again for improving weather as we look further out towards the Spring Bank Holiday weekend.

 

UKMO UKMO shows SW winds developing across the UK next Sunday as pressure falls with rain in the NW gradually extending SE to other Northern and Western areas through Sunday and no doubt on to all areas to start next week.

 

GEM The GEM operational shows the deterioration much more restricted to Southern and Western areas as High pressure holds further to the NE and low pressure lies much further west and SW than the models counterparts. As a result Southern and Western areas will see rain while northern and Eastern areas stay drier with some brighter spells in a SE flow.

 

NAVGEM NAVGEM continues to show Low pressure slip down into the UK from the NW later next weekend with rain and showers developing for all to start next week.

 

ECM shows Low pressure slipping South close to western Britain early next week with rain and showers for all, heaviest and most widespread towards the South and West. Towards the end of it's run the Low fills to the west and pressure begins to rise again with a suggested improvement to drier, brighter and warmer weather again and just well scattered showers by 10 days time. We need to see the ensemble data later to endorse this as a trend or not.

 

MY THOUGHTS  All models continue to predict the improvements later this week as a three or four day event before Low pressure moves down towards the UK from the NW at the end of next weekend. What is less clear is the path this Low pressure takes. Some output brings it down over the UK with rain and showers for all as a result while some other output suggests the Low moves South further to our West restricting the resulting unsettled weather towards more Southern and Western parts in a Southerly breeze. As we look further out towards the Spring Bank Holiday weekend current indications suggest the weather could become rather brighter, warmer and drier again with some sunshine and just well scattered showers.

[knocker]

Looking at the ECM the significant differencs between it and the GFS regarding the 500hPa anomaly is that the ECM has the influence of the trough further west and the eastern ridge further south. The surface low is maintained to the west of the UK Sunday through Wednesday. The exact orientation of the surface synoptics, at this stage, is still up for grabs.

 

[IDO]

No change from the ECM mean.

 

T144:   T240: 

 

Timing and duration respective of the GFS mean, just the angle of the trough the main variant; ECM is closer to N-S, whilst GFS NW-SE.

 

The GFS mean rises pressure from the south by approx. T288, so about 6 days of unsettled weather forecast by the GFS mean:  

 

Building it strongly so by T384: 

 

Early days but maybe a longer lasting pressure build from circa D13.

[Summer Sun]

Some pretty warm air developing on GEM this morning with the high much closer to eastern parts this morning resulting in an south easterly flow

 

 

The high is close enough to keep it dry for most though some eastern parts look prone to some light rain later with southern and western parts the driest

 

Edited May 12, 2014 by Summer Sun

[knocker]

A quick look at the 06z GFS. Certainly looks as if Thursday, Friday and now Saturday could get very warm in England. On Friday the temps could well reach the mid to upper 70s in places. Not in Scotland as thermal underwear still required in Stornoway and later in the whole of Scotland.

[Polar Maritime]

It's looking like the 16th could be a good excuse to "test" the Barby, Before the next Low spins in from the N/W bringing back cool and unsettled conditions by the 18th.

 

Edited May 12, 2014 by Polar Maritime

[Captain Shortwave]

The GFS has finally smelled the coffee and is dropping the trough west of the UK

So now it's a question of how close to the UK will the low be, the further west it is, the drier and warmer it will be. 

UKMO

Agreement on a breakdown on Sunday with a cold front pushing south east, though the south east of England could see another fine and warm day.

 

GFS suggesting Saturday to be the warmest day with a high of 23C across central/southern England

Edited May 12, 2014 by Captain shortwave

[Polar Maritime]

The GFS FI ends with a dry warm S/Easterly, And the Polar Vortex pushed well North.

 

Edited May 12, 2014 by Polar Maritime

[Summer Sun]

UKMO shows the warmest air lasting for another day on Sunday for the south with the SE probably seeing the highest temps

 

 

Rain will slowly move SE wards across the country on Sunday once it clears cooler air will be in place for next week temperatures will be down on those later this week but it'll still be warm in any sunshine most places will see some showers at times but the most persistent rain could be in the west depending on how close to the UK the block to our east is

Edited May 12, 2014 by Summer Sun

[IDO]

Hi Captain

 

I am not sure if you pre-empted the GFS 12z run but it remains close to the 06z mean, that has always had the centre of the lowest uppers around Ireland. The shape of the trough on the op now closer to the ECM 0z trough, N-S rather than NW-SE.

 

T180 06z mean:   12z op: 

 

The GFS run remains wet with below average temps in the whole for 5-6 days from Sunday, as with previous runs:

 

  

 

Afterwards pressure rises remain the trend but lower pressure via cut off lows are never far away.

Edited May 12, 2014 by i'm dreaming of...

[Captain Shortwave]

Just to show the change in one GFS run here is the day 5 mean from the 12z

Previous run

 

A much stronger bridge between the Azores and Russian anticyclones, this makes the trough drop further west. We need this initial push of heights from the Azores high to be a s strong as possible to get the trough as far west as we can.

[Milhouse]

12z GEFS mean now has Sunday looking not too bad the further SE you go with things remaining fine and warm.

 

[phil nw.]

Yes one more day with showers tomorrow then the promised fine spell kicks in for a few days as the Azores high builds in.

Weds to Friday.look good pretty widely with temps maxing out in the region 20-23C in places.

 

Unfortunately it doesn't look like lasting beyond the weekend with the approach of the Atlantic trough already showing it's hand by Friday afternoon just out west and then making inroads into the west of the UK during Saturday.

 

It looks like areas further south and east will hang onto the warm and bright weather through Saturday although from this range there may be some adjustment to the exact timing of the cooler air arriving.

 

Ens means have been fairly steady in bringing this change in the 500hPa pattern in around the weekend although one or two of the recent Op runs have toyed with exact placement/orientation of the trough.

The trend overall though continues for the following days of next week with a cooler and showery outlook for all, with low pressure close by.

Still it will be a nice change to have at least 3 or 4 days of some warm sun later this week.

Edited May 12, 2014 by phil nw.

[Captain Shortwave]

ECM looks a lot better for the UK on Sunday.

 

By the start of the week the low is moving towards the Bay of Biscay. Interesting..........

Edited May 12, 2014 by Captain shortwave

[Milhouse]

Low pressure once again being held at bay on the ECM. Nice day for much of England and Wales on Monday if its correct.

 

[Summer Sun]

ECM shows pressure remaining relatively high on Sunday should be a decent day for England and Wales

 

 

By Monday the low is centered to the SW so the further east you are the drier it could be with the wettest weather in the south west, 850's on the rise again as well with a south easterly flow developing

 

 

T192 sees the low continuing to move away this then sets up an east to south easterly flow with temperatures continuing to rise any remaining rain becomes restricted to the south west

 

 

By t216 the low is moving north again so the south west continues to be prone to rain or showers whilst the further north and east you are the drier it would be warmest weather looks to be in the east and north west

 

 

GEM has failed to update this evening must be a problem with it some where

Edited May 12, 2014 by Summer Sun

[phil nw.]

Interesting to see the ECM Op again delaying that Atlantic trough again, as i alluded in earlier post, some timing differences.

I think it will turn more unsettled next week though as all ens means go with the low near the UK eventually.The south and east perhaps seeing an extra decent day on Sunday if the ECM Op is correct.

[IDO]

The ECM op at T192 has good support from the GEFS with 6 members showing a similar output. This cluster is amongst two other clusters of similar size so quite reasonable outcome from ECM.

 

The uncertainty in the GEFS can be seen from the spread:  

 

The ECM is a lot better than the GFS op but I suspect the ECM ENS are also split as the 15 day 0z ENS hint at:

 

 

JMA go with the GFS solution: 

 

As does NAVGEM: 

 

The GEM will be interesting, to see if ECM has any support...

 

 

[ANYWEATHER]

Really normal weather for May. the Countryside looks great thanks to the Great British Weather. the output is quite simply a normal fest of a few fine days followed by some rain.....

[knocker]

Interesting to see the ECM Op again delaying that Atlantic trough again, as i alluded in earlier post, some timing differences.

I think it will turn more unsettled next week though as all ens means go with the low near the UK eventually.The south and east perhaps seeing an extra decent day on Sunday if the ECM Op is correct.

 

I would essentially agree with that looking at the ECM 500mb anomaly with the trough to the SW of the UK and surface progression that accompanies it. It has backtracked a little and the south is looking okay on Sunday  for the moment but still on a knife edge.

Edited May 12, 2014 by knocker

[Winter Cold]

One thing i struggle with as someone fairly new to model reading is knowing where the weatherfronts will be. Tonights ECM for example looks quite dry to me, but some posts above are saying some rain will be about.

 

I know that the fronts are where the airmasses meet, so as an example below, am i reading it correctly that the charts below from tonights ECM show a front to the north west of Scotland, along the green band?

 

Edited May 12, 2014 by Winter Cold

[Summer Sun]

GEM slowly but surely updating Sunday looks fine for many with pressure remaining fairly high Monday looks best the further north and east you are, remaining warm as well

 

Edited May 12, 2014 by Summer Sun

[Captain Shortwave]

That is interesting, the GEM if anything is more bullish on strong heights to the north east of the UK with temperatures climbing towards the mid-twenties by Sunday and into next week. The cold front barely grazes the north west over the weekend.

ECM ens well.....

Sunday looks alright and better than the GFS

But again low pressure sits just west or over the western half of the UK. Then again is the mean trustworthy here as slight adjustments west or east could bring a drastic change in surface conditions. 

Edited May 12, 2014 by Captain shortwave

[gottolovethisweather]

That is interesting, the GEM if anything is more bullish on strong heights to the north east of the UK with temperatures climbing towards the mid-twenties by Sunday and into next week. The cold front barely grazes the north west over the weekend.

ECM ens well.....

Sunday looks alright and better than the GFS

But again low pressure sits just west or over the western half of the UK. Then again is the mean trustworthy here as slight adjustments west or east could bring a drastic change in surface conditions. 

 

Aye Captain, I think there's a new trend developing here. Could the High Pressure cell be reluctant to leave our shores now? prolonged on some outputs and I get the feeling this is only the beginning. Hopefully no drenchfests and 30mph gusty winds to come for a least five to six days now, that's much appreciated Mother Nature, Thanking you.  We can have the plumes and associated Thunderstorms in June, July and August as far as I'm concerned. Certainly some heat to come however, which will be round one of many longer-term I imagine.

Edited May 12, 2014 by gottolovethisweather

[Captain Shortwave]

First heat ramp of the year I think

Temperatures pushing towards 30C in a hot south easterly flow.

Edited May 12, 2014 by Captain shortwave