Model output discussion 13th Feb onwards

[phil nw.]

Yes a warm up looks likely by the weekend as the chilly feeling easterly veers more southerly.

 

 

the trough out west though is still nearby and after a couple of drier days GFS and UKMO modeling suggests it may make another push back across the country early next week with some further rain moving in to the west.

Still far from a settled outlook but at least we will lose the colder temperatures for a while.

 

[Frosty.]

Yes a warm up looks likely by the weekend as the chilly feeling easterly veers more southerly.

 

 

And yet..today's met office update is for predominantly Easterly winds to continue for the next few weeks, but a warmer easterly with air sourced from southern europe.

[Cloud 10]

Some major differences between the GFS and GEM in the modelling of the Atlantic at 168 hrs.

 

GFS..  GEM..

 

GFS really makes a meal of the troughing whereas the GEM shows a much weaker affair.

 

 

The GEM then goes on to bring the cold in from the North-East,which is consistent with its

00z run.

 

 

 

[phil nw.]

And yet..today's met office update is for predominantly Easterly winds to continue for the next few weeks, but a warmer easterly with air sourced from southern europe.

Yes the high sinks se somewhat and then we see the warmer flow off the continent Karl.

We will have to see how much influence the Atlantic trough just out to the west will have as we go into next week.

The 12z UKMO  run shows the wind eventually turning sw for southern areas as frontal systems move in although GFS keeps us in a se flow.

[East_England_Stormchaser91]

A real rare kind of setup if you like could well be happening in this coming week! Very warm plume of SE winds from Mid Africa! 

Under local topography, the fens for example may well breach 20c on quite a few days. Parts of Holland could well be experiencing temperatures into the mid twenties :O ! Unreal really for March!

[knocker]

Yes the high sinks se somewhat and then we see the warmer flow off the continent Karl.

We will have to see how much influence the Atlantic trough just out to the west will have as we go into next week.

The 12z UKMO  run shows the wind eventually turning sw for southern areas as frontal systems move in although GFS keeps us in a se flow.

 

The 12z ECMWF has low pressure to the SW and high to NE Mon-Weds with a light south easterly flow. Quite warm in the south but cooler in the north. All the 850 temps aren't in yet.

[Summer Sun]

The 12z ECMWF has low pressure to the SW and high to NE Mon-Weds with a light south easterly flow. Quite warm in the south but cooler in the north. All the 850 temps aren't in yet.

 

All in now certainly no signs of anything from ECM

 

[Captain Shortwave]

ECM shows temperatures recovering over the weekend and becoming warm next week as winds slowly veer round from the east to eventually settle between the south and south west. There is a pool of very warm air over Africa which could head our way if things fell the right way. There is a weak surface high over Germany which forms after the high to our north collaspes (this also stops any cold coming our way). 

 

The very warm air stops over Central France, but a stronger feature to our east could potentially see temperatures rise into the low twenties.

 

Conversely the GEM shows the cold side of the coin

A large pool of cold unstable air moves south west which forces the high to retrogress and you get a pretty much perfect alignment for cold air to move towards us.

Problem for me is the movement of that cold air. I just can't see it panning out that way and I favour a more south easterly flow. Both the ECM and GFS are showing a breakdown to a more conventional westerly flow but for the time being I think this is too progressive and any breakdown would be slower.

[Vorticity0123]

The long-awaited high-pressure dominance to the north of Great Britain has finally taken place. A high pressure area has become established over Scandinavia, and it is expected to remain in that region for quite some time (perhaps shift somewhat to the west, i.e. between Scandinavia and Iceland).

 

Despite this high pressure dominance, a small-scale low pressure has been able to develop near Poland. Interestingly, this low pressure is forecast to move in a retrograde direction (i.e. from east to west), and this small-scale feature could be affecting the UK on Wednesday night.

 

Synoptical analysis

 

For the analysis, maps from the HiRLAM (a small-scale, high resolution model) will be used.

 

Initially, the low pressure area is located over Poland, which can be seen below:

 

HiRLAM 12UTC T0h. 

 

The low pressure area is visible as the sub-1000 hPa area to the north of Poland.

Furthermore, the low pressure area is also nicely visible on an IR satellite picture from EUMETSAT:

 

Satellite image of Europe as of 18 UTC (Courtesy: Eumetsat).

 

A clear and beautiful cloud signature can be seen spiralling from northern Turkey to Denmark. The low is currently causing some wet snow in Denmark as well.

 

Forecasts

 

Now it is time to look forward at the forecast for this unusual low pressure system. As mentioned before, it will be moving westward, eventually impacting the UK.

First, a map of Wednesday 6UTC is given below:

 

HiRLAM 12UTC T12h.

 

The low has moved toward Denmark, but it has also weakened slightly. Note that there is a very sharp pressure gradient immediately to the north of the cyclone, which may result in strong winds at that time over southern Sweden, southern Norway and Denmark.

 

Next, a map of 20 UTC is given below:

 

HiRLAM 12UTC T32.

 

What can be clearly seen is that the low has opened up and become a weakly-defined trough. This trough is in this image located to the northeast of London. Still, the trough is visible in the isobars.

 

More importantly, the trough is associated with some very cold 500 hPa temperatures. This will destabilize the atmosphere, which could result in a couple of severe showers. This includes possibilities of hail and (if the conditions are favourable enough) wet snow. Furthermore, the water temperatures of the North Sea are not very cold due to the mild winter of last year. This could enhance the shower activity on Wednesday night. A chart giving the 500 hPa temperatures of Wednesday night as forecast by the GFS can be seen below:

 

GFS 500 hPa temperatures T36 (12Z)

 

It will be interesting to see how the situation will unfold. Nevertheless, it will be worthwhile to watch from a meteorological perspective of view.

 

Sources:

http://www.wetterzentrale.de/topkarten/fsavneur.html

http://static.weeronline.net/images/expertkaarten/hirlam/europe/pressure/2014/03/25/201403251200-201403260600.png

http://www.metoffice.gov.uk/satpics/latest_IR.html

http://www.dmi.dk/vejr/til-lands/byvejr/by/vis/DK/5000/Odense,Danmark

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=dldl&MODELL=gfs&MODELLTYP=1&BASE=-&VAR=z500&HH=12&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD=

Edited March 25, 2014 by Vorticity0123

[Frosty.]

Tonight's Ecm 12z op run shows good continuity from the 00z with a warmer trend as we get to the end of this week and throughout next week with high pressure persisting to the north east of the BI and low pressure to the south west, which means the uk draws a warmer SE'ly flow (546 dam thicknesses) from southern europe / north africa instead of the cold north sea. It looks like the most settled and coolest weather will be reserved for the far north / ne of the uk with the south west having most rain, but a large area of the uk will have rain and showers, some heavy and thundery but with plenty of warm sunshine too, the run ends with a more mobile atlantic pattern spreading east as we finally lose the influential high pressure blocking to the NE. It really has been a dramatic turnaround from the ecm since the cold 12z last night.

Edited March 25, 2014 by Frosty.

[Frank Trough]

 

UKMO looks a bit different at t+144 to the others. Not quite sure which way that would go but i think it could go colder from the northeast more quickly than GEM and  more quickly than theGFS does (eventually) FI.

 

I'm not buying the ECM tonight. I think a brief warmer spell next week before we descend towards something much colder from the northeast towards the first weekend in April.

 

I just think things are primed for the high to move towards greenland at some point - perhaps the UKMO too quick but i would go with the GEM (which is more similar to the ECM of last night).

 

So, plenty in the short, mid and long range to keep everybody interested i think!

[damianslaw]

The turnaround from the ECM today is signs I suspect that the models are struggling at the moment. GFS eventually shows a cold NE feed. So its all a bit swings and roundabouts and a fine line between a colder northerly outlook and a much milder southeasterly outlook albeit one plagued with cloud.

 

UKMO is suggesting a much deeper trough over mid atlantic which would quickly cut off any SE flow.

 

Lots of uncertainty at present. Don't be surprised if they flip again tomorrow to a colder outlook.

[summer blizzard]

Anybody got the CAPE chart? With pressure being relatively low it could be enough to spark some potentially thundery showers.

[Cloud 10]

The ECM operational run in its latter stages is once again a long way from its ensemble mean and looks like an outlier.

 

op run..  ens mean..

Edited March 25, 2014 by Cloud 10

[Barry12]

Warm air from Africa, with temperatures soaring into the early 20's sounds good

The mean is playing catchup

[picog]

Ensembles seem to think things might warm up — throughout the UK too.

[Frosty.]

The Ecm 00z op run continues the warmer trend for the third run in a row, winds becoming SE'ly during the weekend and throughout next week with high pressure to the north east and low pressure to the south west, these are the ingredients for increasing warmth, temperatures could soar well into the 60's F this weekend and into the low 70's F next week with air sourced from southern europe / north africa. Most of the weather action, i.e. showery rain looks like being further to the west / southwest of the uk with most areas becoming fine but with a risk of a heavy thundery shower, it's only towards the end of the run when the weather becomes more generally unsettled and a little cooler with low pressure taking over.

[Summer Sun]

I was pleased to see the beeb talking about it getting warmer by the weekend last night always nice to have the experts coming on board so early in the week

 

GFS continues its warming trend though maybe something cooler in the north as we approach mid next week

 

[draztik]

I think its a given it will be mild/warmish this wkend Gavin, tho not for all - as parts of NI and Scotland will be cool/cloudy.

Thereafter, it appears the ext ecm is now signaling the cold it had progged for days 10-15 is starting to recede to something more akin to normal. Not unexpected, as the other ensemble models never saw it.

Edited March 26, 2014 by draztik

[stodge]

Morning all

 

While some continue to sing the praises of ECM - despite what has been a poor performance by that model this winter - generally when it shows what they want to see, I'll play the same game and mention this morning's GEM output which keeps northern blocking firmly in charge:

 

http://modeles.meteociel.fr/modeles/gem/runs/2014032600/gem-0-216.png?00

 

Very unsettled for the south in particular leading to this:

 

http://modeles.meteociel.fr/modeles/gem/runs/2014032600/gem-0-240.png?00

 

ECM played with this scenario a couple of days ago but GEM has kept it and note the continued northern block.

 

http://www.meteociel.fr/modeles/ecmwf/runs/2014032600/ECM1-240.GIF?26-12

 

ECM very different - much lower heights to the north and west and while HP might topple over the British Isles, the Atlantic looks close at hand.

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014032600/gfs-0-240.png?0

 

GFS Operational 00Z at the same timeframe - the continental feed on the way out but note the heights

 

http://modeles.meteociel.fr/modeles/gens/run/gens-0-1-240.png?0

 

Control already shows the return of a more mobile Atlantic flow in early FI.

 

So it's GEM to keep the northern blocking versus ECM/GFS who want to break it down at the end of next week and bring in something more mobile with the Azores HP returning to its usual place.

[knocker]

Sticking to next week I don't find that the ECM has changed it's position that much

 

The 500mb gpm five day anomaly mean from the 31st is broadly the same with the positive anomaly lying NW/SE to the NE of the UK and the negative lying to the SW. The ens is similar but with the positive retracted a tad.

 

This gives a southerly airstream and the 850 temps quite positive leading to quite reasonable temps of 17C-19C in south and east ( except Cornwall, probably 12C) at beginning of month before somewhat cooler at the end of the week.

Edited March 26, 2014 by knocker

[ANYWEATHER]

Any showers tonight could well be wintry even at low levels, dewpoints are just about favourable for that......

[Summer Sun]

The change from a colder easterly wind to a warmer south to south easterly begins on Saturday

 

 

British summer time arrives with temperatures well into the teens for England and Wales we could see 20c hit somewhere

 

 

It could be slightly cooler in northern England by Monday but in the south it remains warm

 

 

Tuesday sees the north south split again

 

 

By Wednesday temperatures drop down for all

 

[phil nw.]

Starting on Saturday we may well see 3 or 4 days of much warmer conditions with some pleasant sunshine away from North sea coasts of ne England and e.Scotland where the breeze still comes off the sea.

The T84hrs fax  and 06zGFS shows the warmth coming up from the continent on a more southerly wind by the weekend.

 

 

the frontal system in the west finally moving away as it dies out.

Some uncertainty on what happens around midweek onwards but the Atlantic trough is modeled quite close out west.

At the moment it seems frontal systems will affect southern and western districts from this with other areas perhaps hanging to the brighter weather for a while longer.

 

[Summer Sun]

UKMO showing some cooler air moving down from the north at t144