Will Hand's Forecasts...

[Neilsouth]

As for the outlook, still pretty consistent from all models (even GFS coming

more into line) of an increasingly cold easterly flow with risk of gales in

the SW making it bitterly cold. Dartmoor, the east coast of Devon and

Cornwall will have significant below zero wind chill. Eventually day maxes

of 1-3C will be common by the weekend. Chance of snow grains in southern

counties and far SW. (Cornwall may see some rain/snow from continental cold

pool as it tracks west over France). OTOH Scotland could have some beautiful

dry & sunny winter days, especially in the mountains above the inversion

where it could feel quite warm in the sun! So at least a week of cold raw

easterlies after Boxing Day looks on the cards with a gradual fall of

pressure from the SW and that's when it will get really interesting as

milder air tries to push in as we get into 2009 .....

Will Hand on uk sci weather.

Mods told me to post it here

[BARRY]

Will Hand on uk sci weather.

Mods told me to post it here

well thats the best post i have seen for this neck of the woods

[Neilsouth]

Well what a set of model runs today, a lot of eye candy for cold weather

fans and all to play for even if it is in Fanatasy Island, yes I've been

reading the TWO board LOL :-))

Remember ECMWF has hinted retrogression for a while now and now ensembles

and other models are backing this up with a high transferring to

Greenland/Iceland area by New Year opening the door for a long cold spell

with some proper snow over the UK in January. This might get serious, but

too early to tell that yet, still a chance it won't happen but it has to be

up to 60% it will occur in some form or other.

All eyes now on the next 12Z ECMWF run.

COME ON :-)

Now where did I put my *big* axe?

Will

Edited December 23, 2008 by neilsouth

[Neilsouth]

Well as predicted the cold weather has duly arrived now despite 850hPa

temperatures and 1000-500 thickness being well up (as explained earlier).

And it is going to stay cold and probably get colder as deep cold air starts

to advect SSW'wards later this week.

We now have a distorted omega block with the jet splitting. One portion

heads north from Hudson Bay rounding Greenland maintaining the

Greenland-Iceland block, the other part heads east along roughly 50N. Both

these jets will have a part to play in the outlook.

The northern portion will help maintain the block by bringing lower PV air

northwards but then as it comes south again to east of Iceland this will

spin up depressions due to high PV coming south and the latitude effect.

The southern portion will trigger depressions in the normal way which should

mostly dive SE'wards into Biscay/Spain. However, ...

Next weekend into Monday the northern part has every chance of developing a

North Sea low veering the wind and advecting sub 516DAM air into UK bringing

widespread heavy snow into eastern and northern areas and later the SE. I

rate this as a 50% chance. The southern jet will always offer the

possibility of milder Atlantic air pushing into SW England as a low runs

along the Channel followed by another surge of very cold air from the north.

This would give rain in the SW with heavy snow above 250m asl but heavy snow

over Wales and Midlands and later SE England. I rate this as a 30% chance.

So up to the weekend mainly dry and cold with occasional flurries of light

sleet or snow and a lot of cloud with a few breaks at times, but then by

next Monday ...

50% chance heavy snow coming down from northeast

30% chance rain turning to snow coming up from SW

20% staying mainly dry everywhere.

So there you have my theme, staying cold with an increasing risk of heavy

snow from the weekend onwards.

Northern Ireland, NW England possibly seeing least. Low lying parts of SW

England likely to have rain or sleet rather than snow unless the system from

the northeast develops more.

I shall not update on every toss and turn of the GFS or other models it is

understanding the broad picture that is the key and that is what I and Joe

laminate floori always aim to do.

Ciao,

Will

Edited December 29, 2008 by neilsouth