Model Output Discussion - 12th December Onward

[karyo]

It appears that our luck is about to run out! By early next week, we are likely to see the cold zonality replaced with some benign mild weather and then posible a pressure rise from the south...

Karyo

[ANYWEATHER]

Well make the most of the nest five days. Even those are being downgraded with none of the wipe outs predicted (good). The snow looks like it will also be a non-event for the south. From Monday cool HP till the new year. Yawn, yawn...wake me up when September comes!

As far as Im concerned its way to early to put what exactly it will do of Friday. Very complicated set up, and to my eyes the risk of the strongest winds wont be so much an issue as first thought, but I do think there is a Snow potential for the Southern Uk especially for the Midlands and Parts of Wales....way to early to cross the teas or dot the eyes at the moment. :fool:

[NorthNorfolkWeather]

well take your pick about where the low might be by Friday 12z. Gfs sees it exiting the coast of East Anglia with a centre of about 971mb; UKglobal has it over the Dorset are just below 980mb and their NAE model shows it at the same time as a double centre one bit ( nope its 2 tiny centres near Anglesey and the main centre south Midlands (maybe Oxford area) centre there 970mb.

So it remains uncertain just where the precipitaion will be, how far north, wil lthere be any snow on low ground, and how strong, even WHAT direction the winds may be.

oops I forgot the ECMWF

It has it just off the Lizard point with pressure a touch below 978mb.

Thus if you look at the isobars on the models I've mentioned you get just about every direction on the compass and a variety of strengths from Forec 1 to about severe gale 9.

<B>The joys of trying to forecast in the Uk.</B>

I'll give it a rest today.

Thanks John,

I hope others will read what you say and realise that forecasting this little beastie is extremely difficult. Small variations now can stil move it north or south by 100 miles and that, as you say above, can change everything.

I personally hope it runs further south, as it has quite a bit of destructive potential.

[johnholmes]

way to early to cross the teas or dot the eyes at the moment. :fool:

very very true as I did try and comment last night

[Frosty.]

I don't think the final track of the stormy low will have any impact on next weeks weather now, there is general model agreement that high pressure will begin to push north and tilt the jet sw/ne with milder winds blowing around the top of the high with lows tracking to the north of the uk, it doesn't look particularly mild but temps returning to average or slightly above and the latest models have eliminated the risk of snow for the immediate run up to christmas and big day itself for all of the uk. The ecm 00z shows a large anticyclone covering the southern half of the uk by T+240 hours with fog and frost and the jet much further north meaning that northern britain would be milder than the south, still no sign of any major pattern changes favouring widespread wintry weather.

[dragan]

ok so looking at models, im not sure what to happen over christmas, some people say to be milder than of now............met have say for a few days that below normal temperature. Far to early to be say what exact weather over christmas, but does anyone even know what sort of pattern we be in??? Even this seems to be very debatable, or am i wrongs?

(perhaps its case where people only think about there area, not all of UK)

[kold weather]

Thursday night now looks really interesting, the GFS gives a pretty good snow event overnight for the Midlands as the colder air digs down behind the low so its something to really keep an eye on.

ECM also has a BIG snow event for the south, focus is about 100 miles south of the GFS/NAE, probably 5-10cms for most if the ECM came off in the south.

[I remember Atlantic 252]

Thursday night now looks really interesting, the GFS gives a pretty good snow event overnight for the Midlands as the colder air digs down behind the low so its something to really keep an eye on.

ECM also has a BIG snow event for the south, focus is about 100 miles south of the GFS/NAE, probably 5-10cms for most if the ECM came off in the south.

come on GFS lol! lets see where 6Z places low/cold air etc, still think it turns milder on friday, then cold again Sat night

[Iceberg]

NAE does not back the ECM and the 06Z takes a largish 970 centre over the midlands, I really can't see the ECM being right, nor the NAE backing down this much over a 36 hr period.

Edited December 14, 2011 by Iceberg

[nick sussex]

The NAE has made a big shift southwards in the low at 42hrs:

http://www.weatheron...V=0&WMO==

The 48hrs is likely to lead to some excitement!

Edited December 14, 2011 by nick sussex

[Iceberg]

Yep the NAE tracks it along the south coast now and produces a very bad snowfall for the midlands with 10-15cm during Friday Morning rush hour. Incredible really.

[I remember Atlantic 252]

The NAE has made a big shift southwards in the low:

http://www.weatheron...V=0&WMO==

thats good NAE had it too far north for my area, pink over my area at 48

[nick sussex]

Yep the NAE tracks it along the south coast now and produces a very bad snowfall for the midlands with 10-15cm during Friday Morning rush hour. Incredible really.

For some reason the models just can't seem to handle this low, they're all over the place, I don't think we've seen the last of the changes.

[Frosty.]

It appears that our luck is about to run out! By early next week, we are likely to see the cold zonality replaced with some benign mild weather and then posible a pressure rise from the south... Karyo

I only like this post because it reflects exactly how the models are looking for next week, the weather next week looks boring with rather cloudy but mainly dry and mildish conditions in the days up to christmas and possibly over the entire festive period.

Edited December 14, 2011 by Polar_ Low

[shedhead]

The ECM track is likely to be more accurate, but the system is not bumping into air that is cold enough to produce snow – any areas that did see snow as a result of the wrap around on the Northern flank would have to see rain first.

You will need to be on the highest ground in the South Midlands/Northern home counties IMO.

Tend to agree witth this, just not enough cold air in situ to produce meaningful snow across a wide area, though no doubt there will be some wet stuff on ground above 100m in particular. On low ground a

horrible cold rain and sleet mix looks the most likely, but if skies clear early enough it could be very icy come Friday morning, especially on what proves to be the northern edge of the wintry mix. Looking

towards Xmas I personally prefer what both models are showing at T+240hrs, far better than the feared hairdryer and giving the chance of some overnight frost and daytime sunshine... at least down here

where it has been soooo wet recently.

[TEITS]

The ECM track is likely to be more accurate, but the system is not bumping into air that is cold enough to produce snow – any areas that did see snow as a result of the wrap around on the Northern flank would have to see rain first.

You will need to be on the highest ground in the South Midlands/Northern home counties IMO.

At this stage I wouldn't want to say which model is more accurate because they all keep changing the position of the LP. However out of all the models my choice would be between the GFS/NAE because in my experience these models handle the +0 - +72 timeframe better than the ECM. The ECM is a medium range model and appears to handle the +144 to +240 timeframe better than the GFS.

[Radiating Dendrite]

Interesting.

I am still a little cautious about the snow risk and think the air will be just a tad too mild for snow on low ground.

I am travelling from London to North Wales on Friday evening. First of all my journey was going to be disrupted by wind and now it could be snow!

[Brum Watcher]

NAE purrfect for the Snow STARVED Midlands!!!! Unbelievable really!! have doubts if it will happen though!!!

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=ukuk&MODELL=nae&MODELLTYP=1&BASE=201112140600&VAR=prty&HH=48&ZOOM=0&ARCHIV=0&WMO=&PERIOD=

[Radiating Dendrite]

NAE purrfect for the Snow STARVED Midlands!!!! Unbelievable really!! have doubts if it will happen though!!!

http://www.weatheron...=0&WMO=&PERIOD=

It is very marginal though.

850s just nudging -5 and 2m temps of 2c.

I think below 150m it will be a sleety mixture. Above this height could see some snowfall, with accumulations above around 200m I would say going of the NAE.

[BLAST FROM THE PAST]

I have favoured the southerly tracking / channel runner LP for sometime and the synoptic set up of trough to our NNE and secondary channel LP looks close to the mark. I would not be surprised at a snow upgrade over next 24 to 36hrs [though that won't be asking much as not a lot of snow is forecast yet]. More of a N than NW flow to follow potentially too, ridge holding a tad longer?

BFTP

Edited December 14, 2011 by BLAST FROM THE PAST

[Zakos]

Snowfest for the midlands it's looking more likely with each run. Meteogroup ( don't know what model they use) backing up the NAE by forecasting heavy snow for my area on Friday. I have never seen these and the GFS to be wrong in such a short time range. If the met officea do issue a heavy snow warming, it's nailed IMO.

[Radiating Dendrite]

Snowfest for the midlands it's looking more likely with each run. Meteogroup ( don't know what model they use) backing up the NAE by forecasting heavy snow for my area on Friday. I have never seen these and the GFS to be wrong in such a short time range. If the met officea do issue a heavy snow warming, it's nailed IMO.

48hrs out and you think it is nailed?

Have you not been watching the models in the last few days, changing from run to run.

It could all end up a rain-fest quite easily, with snow likely to be very marginal. Even if it did snow, it could be falling onto wet surfaces soaked by earlier rain so may not stick.

[Ruzzi]

Snowfest for the midlands it's looking more likely with each run. Meteogroup ( don't know what model they use) backing up the NAE by forecasting heavy snow for my area on Friday. I have never seen these and the GFS to be wrong in such a short time range. If the met officea do issue a heavy snow warming, it's nailed IMO.

I wouldn't bank on it even if the MetO do issue warnings. There was amber warnings for here last night for blizzard conditions and accumualtions of 10cm or more on ground above 100m, I'm at 200 meters and it was a sleety/rain mix with absolutely nothing close to accumulations (not even slushy deposits) just soaking wet!! A poor decision from the MetO on this one I felt as it was clear that there was going to be no lying snow on ground below around 350-400m.

[Zakos]

48hrs out and you think it is nailed?

Have you not been watching the models in the last few days, changing from run to run.

It could all end up a rain-fest quite easily, with snow likely to be very marginal. Even if it did snow, it could be falling onto wet surfaces soaked by earlier rain so may not stick.

"IF"The met office issue a warning I said. I am aware of the changes run to run, but majority of the runs have showed heavy snow in the midlands. Snow is forecast to be heavy and prolonged. "IF"it does so, then it won't matter about the wet surfaces.

[ANYWEATHER]

The 850s are not the issue in this situation, it is the surface temps ahead of the arrival of the PPN assuming you are on the right side of the system – the Northern side.

I’m at work so can’t look at or post past similar set-ups but from memory Jan 22/23 1984 looks a similar arrangement synoptically, but I’m sure the air ahead was slightly colder than tomorrow night.

Also depends on how heavy the precip is which of course will bring the "evaporative cooling" effect into full swing given enough heavy precip. Still see signs of something pretty Wintry across the Midlands and Wales from the latest run of the 06z Gfs. :smilz38: