Model Output Discussion 31/03/14 onwards.

[Frosty.]

I hope the Arctic cold delivery engine works for the uk next winter :-)

 

Latest models show a gradual descent into unsettled weather this week with showers and longer spells of rain, heavy and thundery at times but with pleasantly warm sunny spells too, the southeast holding on to the 22-25 celsius warmth for longest but tapering off to average to rather warm by friday, much sooner than that for the north and west.

[Gibby]

HERE IS THE LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM TODAY MONDAY 19TH MAY 2014.

 

THE CURRENT GENERAL SITUATION. Low pressure down to the SW of the UK will spill a warm but slack SE flow across the UK with a trough close to the SW generating some thundery rain at times, this moving slowly NE tonight.

 

GFS The GFS Ensembles show Low pressure positioned over Southern Britain through the working element of this week. this will generate showers and some longer outbreaks of thundery rain across Southern and western areas in particular but as the week moves on nowhere is immune. as a result of extra cloud cover temperatures will fall somewhat through the week. Through the Bank Holiday weekend Low pressure tries to move away further north and NE with a slow rise of pressure across Britain. However, showers still look likely over the bank Holiday and beyond and it looks like things could warm up again later in Week 2.

 

UKMO UKMO has slack Low pressure positioned near to Eastern and Northern Britain with pressure gradients slack over the UK. Instability in the atmosphere is likely to be responsible for slow moving and heavy, thundery showers with bright intervals through the Bank Holiday weekend with average temperatures.

 

GEM The GEM operational shows a showery week to come as shallow Low pressure lies close by. Through the extended weekend showers will become more restricted towards the SE with pressure building towards the NW from the Azores with this rise of pressure extending to all areas next week with sunshine and rather warm conditions probably developing again later next week.

 

NAVGEM NAVGEM also has low pressure close to the SE of the UK, albeit very slack and ill defined. It's presence though will be sufficient to generate showers over the bank Holiday weekend over England and Wales while Scotland look like falling under a ridge of High pressure with drier and brighter conditions here. 

 

ECM also shows Low pressure lifting away North out of Britain early next week though it may not be in time to prevent a largely showery weekend for many but it by no means shows a washout with plenty of dry and bright weather around between the showers under light cyclonic winds. Later next week with higher pressure moving in from the SW it may well become bright, dry and warmer again briefly especially across England and Wales before more showery low pressure moves down from the NW late next week.

 

MY THOUGHTS  Low pressure close to Southern Britain over the next 5-7 days look like maintaining the risk of thundery showers and outbreaks of rain at times with temperatures gradually subsiding slowly down though humidity will stay high. There is some support now though for Low pressure to gradually migrate North and East early next week allowing a ridge from the Azores High to re-establish itself towards England and Wales for a short time bringing dry and bright weather back though Atlantic fronts could affect the NW at times extending further South again late next week.

[Frosty.]

Yeah something for everyone, those who like unsettled, those who like warm sunshine..everyone should be happy with the spring so far.

[Summer Sun]

A short lived Azores high on show from ECM Op this morning

 

 

Before a breakdown commences from the north west though the south would hold onto the settled conditions for another day

 

 

The ECM ensemble is still going for a pressure rise later however this time it comes from the Azores rather than the NE like last night

 

 

GEM on the other hand builds the Azores high in from Sunday showers become increasingly confined to the SE initially before the high moves across all the UK turning things drier and warmer for all

 

Edited May 19, 2014 by Summer Sun

[vladthemert]

is this down to el nino effect.  I read somewhere someone said if the second two weeks may very warm it spells for unsettled summer.

Edited May 19, 2014 by Polar Maritime
Please keep to Model Discussion, Thanks.

[knocker]

There is no El Nino effect at the moment unless it's something not known. The SSts have only just got above the threshold so it will be nearly three months before one  is declared assuming they stay there. Ergo there is no reason that I know of to say El Nino will effect our summer. Just  my opinion of course.

Edited May 19, 2014 by knocker

[Polar Maritime]

Please can we keep to Model Discussion in here, There are plenty of threads for other related Topics.

 

Thanks.

Edited May 19, 2014 by Polar Maritime

[draztik]

No doubt many will be hoping the ECM control is just ..well...wrong!

Days 3-8,6-11,10-15 temp anom.

[IDO]

Yes ECM op again showing the milder option in the last two runs, as it did a few days ago, before it changed its mind. The London ECM ENS suggest two camps again:

 

 

A well below average cluster and a warm cluster. The GFS op and Control on the 06z go with the colder option:

 

  

 

The GEFS are not convinced yet that the promising pressure rise from around D8 is a sustainable pressure rise (ECM 0z also leaning this way with a trough from the NW edging SE at D10). From around D12 they give it another shot and more members run with it, about 25%, and they show up in the London ENS as the warmer solutions by D15.

 

Still difficult to call.

 

 

 

 

[Summer Sun]

Interesting run from UKMO at t144 it is now showing high pressure steadily moving closer to the UK by Sunday could be building just in time for the final BH Monday till the end of August

 

 

GFS also has a similar idea

 

 

Running GFS 24 hours and pressure rises not a completely dry picture but there would still be some drier and brighter spells especially in the south

 

 

Then pressure falls once more

 

 

GEM showing the most persistent rainfall would be in Ireland and western parts the UK

 

Edited May 19, 2014 by Summer Sun

[reef]

Interesting run from UKMO at t144 it is now showing high pressure steadily moving closer to the UK by Sunday could be building just in time for the final BH Monday till the end of August

 

GFS also has a similar idea

 

Running GFS 24 hours and pressure rises not a completely dry picture but there would still be some drier and brighter spells especially in the south

 

Then pressure falls once more

 

GEM is trickling out unlike GFS GEM keeps the low out west as a result the wettest weather would be in Ireland and western parts the UK

 

 

 

There's more to things than just how high pressure is though, you need to look at the overall pattern. To me, it looks like we're going to be in a high pressure sandwich with the mean trough over the UK bringing unsettled weather for the next week or so. The main body of the heat looks to be over Eastern Europe and Russia with the last of the cold pushing eastwards from the Svalbard area as a weak high pushes into Greenland. The Azores high looks stuck in its traditional place for now.

 

The jet looks pretty weak so its going to be a stagnant pattern for a while:

 

http://www.wetterzentrale.de/pics/Rtavn12014.gif

 

An unsettled 5-7 days with above average temperatures (more especially by night) and frequent heavy showers or thunderstorms looks most likely.

[phil nw.]

There's more to things than just how high pressure is though, you need to look at the overall pattern. To me, it looks like we're going to be in a high pressure sandwich with the mean trough over the UK bringing unsettled weather for the next week or so. The main body of the heat looks to be over Eastern Europe and Russia with the last of the cold pushing eastwards from the Svalbard area as a weak high pushes into Greenland. The Azores high looks stuck in its traditional place for now.

 

The jet looks pretty weak so its going to be a stagnant pattern for a while:

 

http://www.wetterzentrale.de/pics/Rtavn12014.gif

 

An unsettled 5-7 days with above average temperatures (more especially by night) and frequent heavy showers or thunderstorms looks most likely.

Yes pretty much agree with that .

The shallow upper trough looks like hanging around at least for the rest of this week just gradually filling but still maintaining some instability.

Some notable heat showing just to our east over the continent and into western Russia over the next few days.Those areas lying on the warm side of the trough bringing sub tropical air quite far north.

They could get 30C max's in some spots so an early season heat wave for them.

 

 

The storm risk extending along the boundary of the air masses over the near continent as well as the UK.

The Atlantic low tries to push some cooler air further east as the week goes on so a little cooler by the end of the week with continuing showery outbreaks around amongst the sunny breaks by the looks of it..

[Summer Sun]

ECM still going for a steady rise in pressure from BH Monday

 

 

Temperatures wouldn't be as high as the past few days but still very pleasant in any sunshine with something warmer on offer later for the SE

 

 

EDIT JMA also showing a steady rise in pressure

 

 

I know JMA isn't used much on here but I'm fairly certain its well regarded by the met office from what Ian Fergusson said on here last "winter"

Edited May 19, 2014 by Summer Sun

[knocker]

Regarding the extended weekend I tend to think that the upper trough is holding sway and and the upper air transport is cyclonic rather than having a longer fetch from the warmer regions to the south and east. This to me indicates rather normal STs but doesn't rule out transport from the norther regions of France. It's all still a bit knife edge..Will check the EPS later.

Edited May 19, 2014 by knocker

[Captain Shortwave]

There seem to be a trend of the winds swinging east/north easterly next week as high pressure starts to dominate across many parts of the pole with weak low heights setting up over southern Europe. At the moment it doesn't seem to affect our weather too much with temperatures near normal with showery bursts of rain at times.

ECM

GEM

 

Looks very complex though and the Atlantic jet is virtually non existent. Anything could really happen to be honest. Though there is ensemble support for this evolution to a cyclonic easterly maintaining the showery theme, though eastern areas could experience more cloud at times.

[Frosty.]

The models show a more unsettled spell developing with showers and longer spells of rain, some heavy and thundery but there will also be some warm sunshine, however, temperatures across the uk will return to near average later in week with an atlantic airmass. Looking further ahead, pressure rising a little for the south with the best of the dry and sunny weather and the north then having most of the cloud and rain, as well as the strongest winds.

[bluearmy]

The second ECM op run with strange slp patterns in week 2.

Hlb and lowish euro heights courtesy of a cut off shallow upper trough . It all seems to be lacking direction. I guess we have to wait and see what feature is going to take control in our part of the hemisphere. If it stays like this, them somewhere in Europe is going to get very hot indeed as we go into June.

[knocker]

The second ECM op run with strange slp patterns in week 2.Hlb and lowish euro heights courtesy of a cut off shallow upper trough . It all seems to be lacking direction. I guess we have to wait and see what feature is going to take control in our part of the hemisphere. If it stays like this, them somewhere in Europe is going to get very hot indeed as we go into June.

 

Yes I was looking at the 500mb anomaly charts earlier for GFS and ECM and how they were evolving the surface analysis and decided to retire for an espresso in the end. I agree it seems to lack direction and at the moment the ECM seems to giving the Azores high more significance than the GFS.

Edited May 20, 2014 by knocker

[Gibby]

HERE IS THE LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM TODAY TUESDAY 20TH MAY 2014.

 

THE CURRENT GENERAL SITUATION. Low pressure is positioned to the SW of the UK filling slowly and moving slowly back towards the SW. Two troughs straddle the UK, each weakening as they move North and NW over Northern Britain.

 

GFS The GFS Ensembles show weakening Low pressure under slowly rising pressure as we move through the Bank Holiday Weekend. The weather likely would be a mix of sunshine and local heavy showers but a fair amount of dry weather too in average temperatures. Longer term indications suggest a continuation of quite quiet weather with light winds and occasional rain but a lot of dry, bright and reasonably warm weather too especially in the South and East.

 

UKMO UKMO has moved towards rather higher pressure this morning over the Bank Holiday Weekend. As a result I can be more optimistic that such conditions will give rise to a decent spell of weather over the weekend for many with some showers too, local but heavy where they occur.

 

GEM The GEM operational is more bullish about holding somewhat stronger Low pressure to the SE of the UK with a cool NE breeze and showery rain at times while the best weather holds out to the NW, close to a ridge extending NE from the Azores.

 

NAVGEM NAVGEM shows shallow and showery Low pressure over England to start the weekend gradually lifting out of the UK as pressure builds gently from the SW.

 

ECM also indicates rising pressure at the weekend meaning the weather as a whole may not be that bad for many over the Bank Holiday as the shallow Low over England fills up. Showers are possible in decreasing numbers day by day before a re-establishment of showery low pressure occurs later next week.

 

MY THOUGHTS  In general this morning there is good cross model support that the Bank Holiday Weekend weather may not be as bad as first thought. Pressure from most output is shown to rise, perhaps to in excess of 1020mbs at the weekend meaning any showers from the unstable upper air will be less widespread than indicated by yesterdays charts. Temperatures will be close to average generally but it will feel warm in the sunshine. Longer term and the models still show rather changeable weather with no definitive pattern indicated on this morning's chart. However, taken as a whole the weather will probably end up being non disruptive with plenty of dry, bright weather mixed in with cloudier and more showery periods and temperatures never straying far from the seasonal average.

[IDO]

ECM Ens beginning to trend from D5 towards the cooler option. Last nights suite including the op moving away from the cluster that hinted at higher temps:

 

 

It appears that the op was again, for a few runs, overdoing the AH ridging. The op now moving slowly towards the GFS scenario of the Atlantic overriding that signal. GFS at D7 has a transient short wave ridge before the flatter Atlantic pattern resumes. It is rather slack as it hits the block to our east. I suspect how the upper trough reacts with this and the other ingredients will effect the surface conditions, though we are seemingly moving away from a sustained pressure build before the month's end. However rainfall forecasts are indicating Thursday will be the wettest day in the next 15, followed by Saturday and then mainly showers.

 

So both GFS and ECM now in the cooler cluster with below average temps, for London, from about Friday, for 5-6 days:

 

 Before they return to near average.

 

Again in GFS FI there is the signal for heights towards Scandi, but this has been a background noise for some days and at the moment doesn't draw closer. No clear cluster from D12, with various solutions though more amplification again does look likely.

 

GEM doing its own thing, with an Atlantic Ridge building from D7 with the cut off trough sinking into S.Europe:

 

 

Not sure GEM handle this type of setup too well. Lately NOAA have not been using the Canadian model in their anomaly blend so that may ring true. NOAA have low confidence in the 8-14 day Conus pattern so that will have implications down stream as to the UK's conditions:

 

 

 

Also hinting at a mixing of various upper and surface conditions from D8, so IMO again nothing conclusive.

 

 

 

 

 

 

 

 

 

[Summer Sun]

UKMO certainly moving to a more settled spell of weather developing for all by BH Monday the odd local showers can't be ruled out but that would be about it

 

The change to higher pressure commences on Friday from NW Scotland

 

 

By Saturday pressure is higher from most northern parts so showers becoming increasingly confined to the south and south west

 

 

By Sunday we are all under high pressure

 

 

Temperatures would be closer to average possibly slightly above average in the south and south east at times but feeling warm for all in any sunshine

[knocker]

Looking at the ECM mean for next week seeking some clarification. Well forever the optimist. The 500mb anomally has a build of heights mid Atlantic with a weak weak trough over the UK with main coldish air south over Europe. It's sticking with this scenario until the end of the run.The surface synopsis has high pressure dominating the Atlantic with an interdeterminate area over the UK. On the basis of this and one or two other factors one wouldn't be looking to quickly for the reemergence of the sun block.

 

[knocker]

A brief look at the GFS output at 06z for 12z at  the weekend without attempting any in depth look at the overview.

 

Friday

A shallow low west of Brest with another over the Shetlands. A band of rain from the Bristol Channel to Lincoln with another just brushing the north of Scotland.  Temps mid 60s  in the midlands and east of England but much cooler elsewhere.

 

Saturday

Low 1004mb mid Wales with rain over most of England and Scotland except for the north.  Temps around 60 in the midlands and east but down to mid 50s elsewhere.

 

Sunday

Low now over Scotland with the rain persisting except for East Anglia and far south.  Temps picking up a bit in midlands and south to mid 60s but again lower elsewhere.

 

Ha the good news. Very little wind.

[William of Walworth]

That's washout territory from those GFS projections for plenty of places, this Friday and Saturday (and Thursday doesn't look rain free at all either). Can only hope that later synoptic updates, and other models, will downgrade those prospects to nearer intermittant showers level.

 

ETA : ie back nearer to Gibby's crossmodel summary from this morning

Edited May 20, 2014 by William of Walworth

[Captain Shortwave]

UKMO looks decent going forward

Definite chance to get heights to build over the north of the UK and into Scandinavia setting up an increasingly warm easterly wind. The south would be more unsettled. 

GFS looks very messy with average temperatures. The Euro/Scandi ridge looks very strong though and looks unwilling to budge. A very weak Atlantic jet too so heights to the north of the UK would definitely be a possibility going forward.

 

Edit - GEM also calling a cyclonic easterly next week

Temperatures shown to be getting back into the 20s again, especially in southern areas.

Edited May 20, 2014 by Captain shortwave