Winter Model Discussion - The Hunt For Cold - 10th Dec

[Matty M]

Very good ECM EPS support for the OP today, best in a long time.

Almost all members show similar cyclonic conditions with a large low pressure centre near or over the British Isles, with unsettled and wet weather at times. Temperatures around average with perhaps mountain snow in the highlands at times.

Right out to T168hr there is absolutely no sign of any cold spell on the horizon.

[Mark Bayley]

Lets hope the aussies are onto something, The BOM shows a Greenland high setting up with a impending northerly at 240 hrs http://modeles.meteo.../bom-0-240.png?

Straw clutching i no but just one outcome of many over the next 10 to 14 days. We can hope

I wouldn't say it was straw clutching. A plausible scenario based upon the upstream signals. I would expect more runs (from other models) to produce something similar over the next few days (i.e. i expect to see some colder runs start to show). Although its just a case of whether we can get the trough to the east of us (1). Support from the ensembles for a mid Atlantic ridge extending into Greenland around that time period

http://www.meteociel...&mode=1&ech=240

(1) Interestingly the ECM mean suggests this could occur, or its at least getting there as you progress through the run!

Edited December 10, 2012 by Mark Bayley

[snowking]

Lets hope the aussies are onto something, The BOM shows a Greenland high setting up with a impending northerly at 240 hrs http://modeles.meteo.../bom-0-240.png?

Straw clutching i no but just one outcome of many over the next 10 to 14 days. We can hope

Not a million miles away from the GFS Control 240:

And the GFS ENS Mean shows similar potential at a similar timeframe:

A little less energy into the atlantic (which, given the difficulty in balancing the energy transfer from NE Canada/Greenland to Siberia, is more than possible) and thats our next potential IMO...very small potential at present but mid-atlantic to greenland ridge looks the most likely candidate.

Some further reading from the 12z GEFS:

gens-1-1-240.png

gens-2-1-240.png

gens-3-1-240.png

gens-4-1-240.png

gens-7-1-240.png

gens-8-1-240.png

gens-9-1-240.png

gens-10-1-240.png

gens-11-1-240.png

gens-13-1-240.png

gens-14-1-240.png

gens-17-1-240.png

gens-18-1-228.png

gens-20-1-240.png

So thats 14 out of the 20 members developing some form of mid atlantic-greenland ridge around that timeframe, all with varying degrees of residual atlantic energy

SK

[Cheshire Freeze]

This is a thread for model discussion ...

And it is quite clear that there is no widespread cold on the horizon in the length of the model runs ...

That perhaps explains why there is nothing to really report here tonight.

As for this seemingly mysterious forecast 'update' from the MO showing an above average Winter, please could you provide a link?

I believe this is what's being referred to...

[Matty M]

Just a quick question, how come there is so much certainty stated by some people that it will be mild well into January now? Models suddenly reliable?

In a few words, yes they are seemingly more reliable as they are more capable of dealing with the upcoming spell of synoptics.

The ECM EPS out to 168hrs is extremely clustered, showing high confidence on the outlook to day 8 at least.

Edited December 10, 2012 by Matty M

[swfc]

Very good ECM EPS support for the OP today, best in a long time.

Almost all members show similar cyclonic conditions with a large low pressure centre near or over the British Isles, with unsettled and wet weather at times. Temperatures around average with perhaps mountain snow in the highlands at times.

Right out to T168hr there is absolutely no sign of any cold spell on the horizon.

Amazing isnt it that if they were showing a severe cold spell they woudnt varify!!!!!!!!!

[SouthPennine88]

I believe this is what's being referred to...

Ahhhh, I missed that chart ... of course ... the met office Winter forecast.

That's the one.

Wait, did someone seriously think that chart was a winter forecast?

[Cheshire Freeze]

In a few words, yes they are seemingly more reliable as they are more capable of dealing with the upcoming spell of synoptics.

The ECM EPS out to 168hrs is extremely clustered, showing high confidence on the outlook to day 8 at least.

Should we all pray for that one solitary cold member to be a trendsetter??? Altogether now.....

[bluearmy]

the trough on ecm mean day 10 is quite a cool one with thicknesses in the low thirties. energy seems to be be passing to our south on the spreads so it doesnt take too much of a leap of faith to see some surprises, especially if the flow is slack and surface cold builds. the position of the mean trough is a bit more favourable on the 12z than the 00z with the pressure from the displacing vortex pushing the russian high a tad further east. not too far as ian has mentioned earlier but ..... oh hang on a minute, i must be in lala land - its mild zonal mobile mush as far as you care to look. apologies.

[bobbydog]

I don't know about that; its base platform is the UKMO.

that may be so but i've seen some huge differences in their output recently, even within the range of the UKMO

[seabreeze86]

If i am being honest what the BOM is showing is where i expect us to go just not as soon maybe 15 days. I think with the trough getting cut off as the atlantic runs out juice and the Russian high backing east will give us our widow of opportunity for us to build a ridge behind the trough, towards Greenland.

A Greenland high is always the safer way to get cold to our small island. Just an idea im learning all the time so go easy on me.

[Gavin Hannah]

Here's a model showing where all our cold has gone.....

https://twitter.com/...6700032/photo/1

Edited December 10, 2012 by IBringTheHammer

[bluenose79]

Cheers Matty

In a few words, yes they are seemingly more reliable as they are more capable of dealing with the upcoming spell of synoptics.

The ECM EPS out to 168hrs is extremely clustered, showing high confidence on the outlook to day 8 at least.

Edited December 10, 2012 by bluenose79

[swfc]

If i am being honest what the BOM is showing is where i expect us to go just not as soon maybe 15 days. I think with the trough getting cut off as the atlantic runs out juice and the Russian high backing east will give us our widow of opportunity for us to build a ridge behind the trough, towards Greenland.

A Greenland high is always the safer way to get cold to our small island. Just an idea im learning all the time so go easy on me.

Hopefully your rite there but given how the model output as faired over the last 14 days i guess lord lucan could be doing countryfile on sunday!!!!Things look set for an atlantic spell of weather and thats about it i reckon.Iv learnt that taking anything pass 96 hours is at best a let down and very frustrating.I could say that all the teleconnections,mjo,nao ete point towards a greenland high forming via the azores high pushing north?Iwont tho because i dont no full stop.Its possible but so is a full onset of zonality"whatever the trend and background signals".All will be revealed and very interesting it is too

[Matty M]

The clusters do begin to diverge again towards December 20th as expected with forecasts so far out.

[Panayiotis]

The clusters do begin to diverge again towards December 20th as expected with forecasts so far out.

I see some good in that chart and that is (assuming the dotted line is the average?) the trend towards colder conditions past the 21st. Edited December 10, 2012 by panayiotis

[Bridbird]

Goodness so much doom and gloom. Hey it's cold at the moment and has been really since the end of autumn, had two falls of snow already this winter, small amounts but lovely to see all the same.. How can anyone be sure beyond 5-7 days ( general pattern only), how this winter pans out. The bbc monthly forecast issued today has reasonable confidence in a return to below/ slightly below temperatures prior to Christmas and turning milder again by the new year. Beyond that is anyone's guess surely as shown by the huge flip flopping of the models over the last week??

[Gavin Hannah]

Well we're t minus 9 mins and counting.... "It's the final coutdown duh duh duh duhhhhhh! do-do do-dooooooo"

[itsnowjoke]

i know that its a true fact that the uk has problems getting snow as we are a island surrounded by warm seas, its just makes me laugh have you ever been in the sea at Blackpool? Freezing

[Gavin Hannah]

i know that its a true fact that the uk has problems getting snow as we are a island surrounded by warm seas, its just makes me laugh have you ever been in the sea at Blackpool? Freezing

One mans freezing is anothers tropical lol.

[IDO]

In a few words, yes they are seemingly more reliable as they are more capable of dealing with the upcoming spell of synoptics.

The ECM EPS out to 168hrs is extremely clustered, showing high confidence on the outlook to day 8 at least.

No surprise there. The Strat experts told us that we would be locked in to a blocked pattern. Of course, there is always the chance, more often than not it seems, that the block will sit in the worse place for cold for the UK. We end up in one of the less cold sectors and also act as a buffer for the cyclonic westerlies. I suspect the block to rub it in now and sit there for a few weeks, just to show that we have just missed the chance for some very cold weather. Plenty of places have nicked our cold including the US.

That is why the ensembles are so close, a locked in blocked NH. I think it is Brian Gaze over on TWO who says that even with a blocked NH there is only about 60% chance of the very cold hitting us.

What is apparent we are entering a cool period. The ensemble mean will be below zero for most of FI (London), and colder the further north:

http://cdn.nwstatic.co.uk/ensimages/ens.20121210/12/t850London.png

I would not suspect much change from the 18z, although it has been living up to it's name with credit the last few runs, so there may be a few surprises.

[damianslaw]

It looks a very wet end to the week unfortunately - really not good news at all, given how sodden the ground is at present, further flooding misery very likely for many as low pressure once again becomes anchored over the country with nowhere to go - synoptics which dominated much of the April-July period.

There are tentative signs of pressure gradually building over the mid atlantic in the run up to christmas aided by the movement of the russian high eastwards - which is what is needed to help trigger the longwave trough on a east/southeast trajectory, which as I said yesterday is the most likely evolution of the projected pattern. It is likely to be a slow painful affair, as we see slow moving bands of heavy rain becoming unstuck across the country under quite cool uppers - making for very gloomy depressing dark conditions, thank goodness we will have the christmas lights to brighten things up.

[chris55]

I see some good in that chart and that is (assuming the dotted line is the average?) the trend towards colder conditions past the 21st.

Dotted line is the average of all the runs added together, not the average for the time of year.

[Thundery wintry showers]

Copied from the other model thread:

Strong agreement that while wintry showers will turn increasingly to snow during tomorrow and Wednesday, they will mostly be stuck out in the North Sea, with a large majority of the country dry and clear with temperatures somewhat below the seasonal average, most especially by night:

http://nwstatic.co.u...b6d9dba1617f42;

http://nwstatic.co.u...b6d9dba1617f42;

Freezing fog may also be an issue in many areas as Ian Ferguson recently pointed out in the south-west thread.

It is looking increasingly probable that our continental blocking will put up very little resistance against the Atlantic frontal systems pushing in from the SW on Thursday and Friday, although the GFS has ditched the Atlantic-driven shortwave over Scotland that it previously showed for Thursday. Precipitation towards the south-west of Britain will generally be rain at low levels as the cold continental air will struggle to fully penetrate into south-western Britain this week. There is still some potential for sleet and snow on the northern flank as the systems head through central and northern England and into Scotland, but it is almost certain to be a short-lived snow event in the areas that get snow.

After the rain passes through on Friday, the UKMO, ECMWF and GFS are all agreed on a showery-looking south-westerly regime, with most of the showers concentrated over Wales and western and southern parts of England, and some also over western Scotland. Sheltered parts of eastern Scotland and north-east England will probably see very few showers, although I rather suspect that the GFS precip outputs are under-doing the inland penetration of shower activity.

Some fairly high CAPE (convective available potential energy) for the time of year is showing up over the seas surrounding southern Britain:

http://nwstatic.co.u...b6d9dba1617f42;

This would support some scattered weak thunderstorms associated with the showery activity over the south and west of Ireland and Wales, and also near the south coast of England.

Long-term prospects for cold snowy weather look like being strongly hindered by that stubborn trough sat in the eastern Atlantic which will keep things moist and fairly mild for a while, although northern blocking is set to remain more extensive than usual which means that once we get rid of that trough, we may see something wintry come our way from the NE- it looks like being a slow process though.

Edited December 10, 2012 by Thundery wintry showers

[Panayiotis]

Dotted line is the average of all the runs added together, not the average for the time of year.

Ye that was what i assumed But thanks. Edited December 10, 2012 by panayiotis