Winter 2009 / 2010 in Western Europe?

[markt]

Brrrrrr!!!!  It's darn cold wherever you are!

Have you much in the way of snow in N Ireland at the moment?  I notice that polar front is just pushing down now.  Met Office has a 'Be Aware' forecast for me, but watching the direction the front is coming down, providing it doesn't run out of gusto it has a chance I think of blowing down through the Cheshire gap to give some of the wintery stuff down here in the west mids...  I kinda half expect when I get up tomorrow morning for it to be white over...

[martinastro]

I'm waiting on that front to arrive here Mark, I expect good snow from it ,with luck. Today there where snow showers on high ground, I went up to the Glenshane Pass and wasn't surprised to see plenty of deep snow around....



Almost got the car stuck in the Ponderosa carpark. That snow has been there since before Christmas and keeps getting more dumped on it, I can only imagine what the conditions will be like tonight. Hope you get the snow Mark!

[martinastro]

19Z Update

The very blocked scenario continues.  A large upper and surface high is located in the vicinity of Greenland and an increasingly cyclonic NE'ly is penetrating SSW towards the UK.  The Atlantic remains blocked and depressions are being sent towards Iberia and the Med giving winter rains to the Med.

The devil is in the detail over the next 48hrs with continuing inter and intra model run variability giving a nightmare forecasting scenario.  The Midday Analysis presented no obvious errors in comparing WV imagery to model forecast fields. The Upper trough coming SE now out of the data sparse greenland area and into the Norwegian Sea.  This is in the domain the NAE and with more plentiful observations it is expected that forecast accuracy should improve for the next 48hrs, though beyond this there contines to be problems in the shape of the block by the weekend. (The EcM for example insists on a more cyclonic look throughout and into the start of next week vs the more anticylonic GFS)

Anyway - lets look at the detail for the next 48hrs...

The upper trough coming south has been causing all sorts of problems over the last 48hrs as it moves into areas of Data coverage vs areas of non data coverage (typical of a trough crossing Greenland), however the 12Z Analysis and Model evolution brings a sharper trough south slower than previous runs of some models.  This has the effect of elongating the trough and allowing it to develop a new surface low in its base which is then locked in by the upper trough where it becomes slow moving before moving south.  This allows a flood of very cold arctic air to move across the whole of the UK.  1000-500mb thickness become quite low (though not exceptional) to bring many areas sub zero maxima through the rest of the week.  High pressure then builds into the North.

The runs over the last 24 hrs have chopped and changed their story - except the consistent ECMWF, which has always preferred a new low developing nr the Isle of Wight as opposed to the North Sea low moving SW (as was in the NAE 06Z)

The 12Z Runs have now fully come in, and there is excellent agreement on the development of a new low in the base of the sharpening upper trough coming SE across the UK tomorrow.  The showers / bands of snow now coming SE across Scotland will tend to become more organised with time into a more coherent band which will come South giving Snow inland and rain/sleet on the Coasts.   the FRont sucking into WBPT of greater than 3C as it comes into Wales and the SW, so Coastal areas seeing Rain/SLeet with snow above 300m or so as WBFL's rise. However some heavy snow is possible inland across N England esp the Pennines and Peaks along with Wales.

Later tomorrow the trough continues to dig in and engage and a new low starts to develop nr the Isle of Wight. The 12Z GFS, NAE, ECMWF all develop the low nr the Isle of Wight and then begin to spin it up - locking in PVA from the trough as it comes SE and deepening the low.  There is broad model consensus of a sub 998mb low off the Dorset/Hants Coast by 00Z Weds, with the milder air pushing into Coastal Areas further to the East of the low.  The positioning and development of the low is CRUCIAL to who gets Snow/Rain, Coastal areas to the East and SE of the Low will see higher WBFL's and WBPT >3C meaning Rain /Sleet with Snow above 300m or so (through penetrating to lower levels in any substained heavier precip) however areas to the North and West of the Low will see Snow, and this could become very heavy.  The low will be developing and under darkness with a falling barometer, the moisture will largely turn to snow anywhere to the North and West of the low. There is some discrepancy on the precip structure , the ECM along with the GFS has the heavier Snow further towards the Home COunties, towards Central England , whereas the NAE has it over CS England (NAE has over 25cm of snow nr Salisbury Plain by the End of Weds) whereas the GFS has 29cm over the SE Midlands.  Therefore the detail is unreliable and we need to see how things develop in the next 24hrs.  The fact that none of the 06Z Models produced anywhere near the extent of the snow means we need to see what the next 18Z Runs bring, however the fact the ECMWF has hinted at this for several days now (bar a couple of runs) gives credence to the idea that if the trough is sharp enough and slow enough then a new surface low can develop just off the coast as in the 12Z Runs.

The low only slowly pulls away on Wednesday with snow lasting through much of the day on the 12Z GM, NAE, GFS and ECM across the South of England, adding to already fallen amounts to give the accumulations mentioned.

Very, very cold further north over the Snow fields, and then on Thursday a brighter day with a cold ENE wind and further Snow showers across the East and SE, penetrating further inland than the models expect, giving another few cm in places.

Paul Blight
UKww Manager - Education/Warnings
Associate Fellow Royal Meteorological Society

[brianb]

Have you much in the way of snow in N Ireland at the moment?

Not here (North Antrim coast), lots of very sleety rain showers falling onto very cold ground, causing problems much worse than snow would. Strong bitterly cold wind too, the air temp is actually above freezing as the wind is off the "warm" sea but it's horrid compared with yesterday when it was still, dry & -5C.

[paulster78]

Snowing like mad here now huge flakes!! It started off wet sleet initially but only for a minute or so, about a centimeter already after 15 minutes!

[martinastro]

Send it this way Paul, it's been a mix of rain, sleet and snow here, but mostly rain, and I suspect it's freezing rain which will be deadly on the roads later. Still waiting for the big snow though. Roads are going to be terrible on Tues morning.

Glad your'e getting the snow. 

[martinastro]

We have the heavier stuff here now, like a blizzard at times.



Snow Forecast Issued: 2010-01-04 20:25:00
Valid: 2010-01-04 23:00:00 - 2010-01-05 22:59:00

Regions Affected
All of the UK.

Synopsis

A complex situation arises for Tuesday. A front coming down from the North will give many a spell of moderate snow and a light covering for most. As this reaches the Midlands it looks like it will become very slow moving with the potential for some fairly significant accumulations. Behind all this will be plenty of snow showers with coastal areas most affected giving places further spells of moderate or heavy snow and local accumulations and again perhaps significant.

Coastal areas will probably see a mix ofrain sleet and maybe wet snow.

Icy roads will be a problem for many so leave extra time for journeys. Transport disruption is likely particularly where snow hits rush hour peaks and where the snow is slow moving.

Later on in the evening is the potential for a significant event but alot of uncertainity remains. Much of Central Southern England and into the Midlands could see some prolonged heavy snowfall giving large accumulations with 5-15cm likely over a wide area. Upto 30cm is possible over the hills. However much could still change so stay tuned for local forecasts on this event.

[paulster78]

Good stuff Martin is it sticking with you?  Its seems to be here although im worried all this cloud cover will raise temperatures enough to start a thaw before more snow arrives tonight/tomorrow.

[markt]

Great snowy pictures Martin!

The sky has clouded over for me now, I could see the moon a couple of hours ago.  It's certainly moving down on the radar, and if the latest forecasts are accurate then potentially quite a dusting of snow awaits me over the next 24 hours. 

[martinastro]

Thanks Mark!! - I hope you get your own snow pics soon with that lot of white stuff heading your way 

It's just spitting the odd snow flake here, nothing much on the ground other than what was there before, looks very dangerous and wet here, clouds seem to be messing with the temp drop but hopefully that will clear away later. Heard reports of heavy snow in Belfast and Maghaberry area. Looks like W areas of NI will get the most tonight, however anywhere could get it, the TV forecasts didn't seem keen on us getting much  .

E areas of Ireland could be in the best place, Tues, for snow, as for mainland Britain...could be serious stuff on the way

[martinastro]

Back to thick heavy snow here!! - looking good, hope it lasts

[Padraig OBrien]

Hi might get my first major snow of this season on the way tomorow or later half about  an inch of ice and snow and the place is lethal

[martinastro]

Good heavy snow showers here during the early morning hours, very beautiful.

ESTOFEX have a t-storm forecast for parts of Ireland valid Tues

http://www.estofex.org/

[Roman White]

Pretty cold, -20C here last night, dewpoint -23C. Since early morning the sky became cloudy, temperature is quickly rising, now is already -11C. By the way, it was -30C last night in extreme northern Ukraine, now that's really cold! 

[martinastro]

NATIONAL SEVERE WEATHER WARNING SERVICE
EMERGENCY Flash Warning of
- Very Heavy Snowfall
For the following areas
- Dorset (Severe)
- Hampshire (Severe)
- Oxfordshire (Severe)
- Southampton (Severe)
- Swindon (Severe)
- W Berkshire (Severe)
- Wiltshire (Severe)
There is a high risk of an extreme weather event affecting parts of Southern England this evening and overnight. A period of exceptionally heavy snowfall is expected with accumulations of 15-30 cm and perhaps in excess of 40 cm. This is expected to cause widespread disruption to the transport network and could lead to problems with power supplies. The public are advised to take extreme care and refer to the Highways Agency for further advice on traffic disruption on motorways and trunk roads.

Issued by the Met Office at 11:35 on Tuesday, 05th January 2010
Valid from 20:00 on Tuesday, 05th January 2010  until 11:00 on Wednesday, 06th January 2010
For enquiries regarding this warning - please contact the Met Office customer centre
- Phone: 0870 900 0100
- Fax : 0870 900 5050
- Email: enquiries@metoffice.gov.uk