Again GFSP wants an Easterly

GEM is feeling the love for an easterly too.

Despite the marginality of it all thanks to a continental pull and low pressure meandering close to northern France or in the English Channel it has to be said that things are potentially very snowy for many parts of central and southern Britain early next week. 

Looks cold enough Steve

I like the optimism, but no mention of UKMO? It has totally dropped the easterly idea this morning.

Credit to the new GFS (as of 12Z run today if all goes to plan) for latching on to the idea before the others (a few GME passes excepted), but credit can only be given on exchange of goods and looking at the huge range of options at +120 nothing is guaranteed.

More runs and all that

It has also totally dropped the trough southeast by day 6... bit much development before arrival though. Still room for a ridge to build north of it the following day I would have thought...?

In any case, the output seems a bit more chaotic this morning, though through it all does come a signal for the sliding trough theme to continue beyond day 6, even from GFS, which is an improvement on recent days.

ECM and GFSP are the most similar when comparing any two models, but ECM not quite as favourable with the trough angle on day 5 and then making more of the new sliding trough day 7 onward. GFSP is almost as intense on day 7 but it isn't such a large feature, and weakens a lot more as it slides SE.

Shorter term, Saturday features widespread snow across England and Wales on GFSP, but rather lacking in intensity for the most part. GFS has more in the way of rain, as it develops the weak secondary low more as it drifts south, pulling some less cold air in from the SW. 

Thereafter the models are so divergent that details become largely irrelevant; day 6 has a large disrupted low with a marked snow/rain likely boundary somewhere across the UK, GFSP has a weak slider far east enough for the SW to have a rain-snow event rather than all snow, while ECM seems to just have a trailing frontal system out west of the UK with weak low pressure development along it.

The position this morning is the least comfortable for those in the far south, where the model output shows the parameters always on a knife edge for rain or snow, with too much of the former creeping in to place much faith in seeing much, if any, snow.

History shows us that we always get model wobbles when approaching a cold spell - because anything which is out of the normal range for our westerly dominated weather is hard to model I guess. But what do the ensembles say this morning? - they generally give a more nuanced picture than wavering operational runs.

Seems to be a lot of optimism on the other forum but I cant see it to be honest. The northern jet seems too strong to allow the block to take hold and we are relying on slider lows and a reload. Very dangerous. I feel this cold spell is hanging on by its embers. The evening runs be will be the most crucial of the winter so far

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY WEDNESDAY JANUARY 14TH 2015.

NEXT UPDATE THURSDAY JANUARY 15TH 2015 08:00

THE CURRENT GENERAL SITUATION A rapidly deepening and vigorous depression will move NE towards NW Scotland tonight with severe gale SW winds veering Westerly tomorrow accompanying troughs across the UK through the period.

MODELS-2 WEEK HEADLINE Rather cold and unsettled with rain, sleet or snow at times with some night frosts.

THE JET STREAM ENSEMBLE FORECAST The Jet Stream Forecast shows a very strong Jet Stream this week weakening slowly thereafter. The flow will remain largely South of the UK through it could return back North across the UK later in the period under Atlantic Westerly winds with rain and showers at times.

GFS OPERATIONAL The GFS operational projects a week to 10 days of rather cold and unsettled weather as the UK lies under a cold trough fuelled by a Jet stream South of the UK and sinking Low pressure troughs down from the NW. The pattern then flattens through Weeek 2 as the Jet flow moves back North in a West to east flow across the UK powered by deep Low pressure back north of the UK with rain and showers for all in nearer to average temperatures.

THE GFS PARALLEL RUN The Parallel run is very similar in context and sequence as the next week looks like staying cold and quite wintry in places as Low pressure disrupts SE in cold air across the UK moving SE. The Jet sream remains anchored well South of the Uk through this period. Thereafter the cold weather becomes displaced by a return of Atlantic westerlies and rain and strong winds at times later in the period.

THE GFS CONTROL The GFS control run completes the set with a variation of a general GFS theme this morning of a week or so of cold weather eventually becoming replaced by milder Westerly winds and rain at times thereafter.

THE GFS CLUSTERS The GFS Clusters show 50% ckusters surrounding less cold and mild Westerly winds around Low pressure to the North of the UK by the end of the period being the most likely event while other show variations of Low pressure more to the NE with chillier NW winds and spells of wintry showers in between the rainbands.

UKMO UKMO this morning shows cold and changeable conditions across the UK as Low pressure continues to move down from the NW at times with rain, snow and wintry showers in equal measure all affecting most of the UK at some stage or another over the period.

THE FAX CHARTS The Fax Charts illustrate a deep and powerful depression moving NE towards NW Scotland sweeping active fronts across the UK followed by a cold and unstable showery West or NW flow across the UK thereafter.

GEM GEM today also shows a cold and unsettled period lasting up to a week or more as cold Low pressure areas sink SE across the UK through next week with rain and snow at times. The model then shows High pressure building across the UK from the SW with frost at night and cold bright days.

NAVGEM NAVGEM builds High pressure North of the UK at the end of the run with a cold and fresh Easterly flow across the UK especially over the South. Following a week of cold and unsettled weather with rain and snow at times wintry showers across the South would end the run with frosty nights, these especially across the North.

ECM ECM this morning continues to illustrate a pattern of Low pressure moving down from the NW at times with outbreaks of rain and snow intemperatures on the cold side of average. Later in the run the pattern remains complex but in essence cold NW winds and showers at times, occasionally wintry will continue to affect the UK.

ECM 10 DAY MEAN The ECM 10 Day Mean Chart maintains a cold and rather wintry look about it still in 10 days time and although there is a reduced risk of any pressure rise to the NE and resultant East winds things still look good in respect in cold weather coming down from the North and NW with spells of wintry showers for all in a NW flow and a Jet flow held to the South and SW of the UK.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend this morning has decreased the chance of much in the way of a pressure rise to the immediate North and NE of the UK with Low pressure continuing to drift down from the NW maintaining the risk of snowfall at times from that source.

MY THOUGHTS The models this morning continue to jostle around with very complex synoptics across and around the British Isles over the next couple of weeks. With a Jet flow running out of steam over the weekend and keeping to the South of the UK for some time Low pressure areas exiting the NW Atlantic are forced SE across the UK next week as cold air lies ensconced over Western Europe. What is a shame and indeed missing from much of the output today is the lack of a pressure rise across Northern Europe and even where it is shown is found to be transitory and collapsible from the power of the resurgent Jet Stream later and Atlantic westerlies later. This puts too much pressure on the cold block and eventually runs the risk of flattening it away South later and bringing back a more transitional zonal Winter pattern towards the end of the period. However, before that happens there is a lot of complex synoptics to come which could develop different evolutions for further out in the coming days and if all else fails we should all experience a cold week to 10 days when the risk of at least a little snow at times is likely for most areas even in the South.

Oh Come on beast you Know better..

For once I actually tend to agree with your always 'negative no matter what, and doesn't bother to post if there's anything positive to say' slant. 

I'd never write off any potential snow event at this range, but at the moment I think the weekend will be mainly a rain event for the South. The METO forecasts currently side with this.

Time for change though 

Is winter over?

Very impressive ecm means this morning even colder than the Op. Suggest some sort of easterly very possible next week

http://www.wetterzentrale.de/pics/Reem1442.html

http://www.wetterzentrale.de/pics/Reem1682.html

http://www.wetterzentrale.de/pics/Reem1922.html

http://www.wetterzentrale.de/pics/Reem2161.html

GFSP would suffice though Rob

That has often been my experience of GFS. You never quite know what it's going to come up with sometimes, especially in FI.

Update from Ian on NW:

As others note, UKMO regard EC DET as progressive outlier. Strong signal for colder or much colder weather next week, albeit extremely low skill on snow risk in any one area (not even worth speculating!). MJO phase root cause for the synoptic 'flip', they say. Some solutions look ominous, but a while before ANY worthwhile deterministic detail emerges for day-to-day prospects after the cold, cyclonic weekend has passed...

Cold week ahead.

I would guess the 'ominous solutions' are ones that really put us in the freezer.

For any who worry and fret with the detail of individual runs, this update from the 'pros' ought to calm the nerves. As ever in this country - get the cold in first and the snow will hopefully arise (usually with meso scale features that have no real chance of being forecast 5-6 days ahead). That the MET are going for colder or much colder next week is enough for me. (Plus I've seen falling and settled snow in winter 2014-15, which tops last year...)

Advice - don't obsess about individual GFS runs. But then this is a forum for obsessives...

Nope 2" overnight

not

The ECM Control run for De Bilt deserves some ominous background music. Plenty of other very nippy runs too, with the 2m mean hovering around 0c from next week onwards.

http://www.knmi.nl/exp/pluim/vijftiendaagse/index.php?run=00

I hope the detractors of James' many musings on the MJO take note of the bit I've highlighted.