Model Output Discussion 17th Dec.2013-12z onwards.

[Stuie]

Quite pleasing there is agreement from both the UKMO and ECM regarding that pretty nasty low system shoving it north (sorry Shetland) and not covering the majority of the UK mainland, considering all the travelling in this period.

 

 

 

Edit: Wonder if the GFS will follow suit as it currently has the low more southerly.

Edited December 20, 2013 by StuieW

[Captain Shortwave]

The one thing the models have done over the past few days after beginning to develop a deep trough over western Europe is to delay the return of the Euro high. This probably means that we might enter a cool/average and unsettled spell though away from fronts and disturbances the weather might break for some clear, chilly and sunny days, especially in the east. The last 36 hours have been great here, 2 sunny days, night time thunderstorms and a frost.

Another thing is the trend to divide the polar vortex into two lobes,  keeping the one over Greenland, with another lobe developing over Siberia. Now can we at the turn of the year develop a strong Pacific ridge in response to deep lows developing over the far East of Asia (triggered by the new vortex position), this in turn amplifies the downstream pattern, resulting in an Atlantic ridge developing. Worth noting the 2 lobes of the vortex places heights over Eastern Russia pretty much by default here. So I wonder if we could develop a northerly followed by an easterly sometime during the 1st half of January.

Edited December 20, 2013 by Captain shortwave

[Methuselah]

Looking at the models as they currently stand, I think that - barring an 'Official' one flake job - the only way we can hope of seeing a proper White Christmas this year, is via a secondary depression: without something to drastically reduce mean wind-speeds, I can only see rain reaching the ground - except in the usual places...We shall see.

[snowmadchrisuk]

Quite pleasing there is agreement from both the UKMO and ECM regarding that pretty nasty low system shoving it north (sorry Shetland) and not covering the majority of the UK mainland, considering all the travelling in this period.

 

 

 

Edit: Wonder if the GFS will follow suit as it currently has the low more southerly.

 

Most people will travel on Christmas eve , and it looks a lot worse at that point .. 

 

[Gibby]

Hi everyone. Here is tonight's attempt to look between the Weather models 12 noon outputs for today Friday December 20th 2013.

 

All models show another deep depression to the NW of the UK with a cold front slipping ESE across Southern and Eastern areas overnight leaving behind a cold and showery SW flow over northern and western areas while a wave travels NE along the cold front over the SE tomorrow delaying it's clearance until evening. By Sunday all areas will be under a rather colder and showery Westerly flow with some wintry showers over the hills and maintained very windy weather. On Monday the weather becomes particularly stormy everywhere as yet another unusually intense depression moves in close to NW Scotland. A series of troughs cross all areas through the day with heavy and persistent rain for much of the day clearing slowly SE later with severe gale or storm force winds giving rise to potential damage in places.

 

GFS then shows Christmas Eve as a windy and very showery day with gales and frequent showers for all with more persistent rain left over from Monday only clearing the SE slowly. Some of the showers will again be heavy and wintry in places , most frequent in the West. On Christmas Day and Boxing Day it looks like being somewhat less windy but rather cold with further showers and longer spells of rain or sleet, especially in the South. Thereafter up to the New Year yet another storm system similar to Christmas Eve's version brings heavy rain and severe gales to all areas followed by sunshine and showers yet again. As we move towards and over the New Year High pressure ridges towards the UK from a position North of the Azores and brings much less wet but breezy weather with more benign conditions over the South while rain becomes restricted towards the North.

 

UKMO tonight shows a wet and occasionally very windy Christmas especially on Christmas Eve. It will become rather cold with some snow showers over the hills at Christmas where a quieter period at the end of Christmas leads us into the approach of the next storm system on the 27th.

 

GEM tonight keeps deeply unsettled weather throughout the three day Christmas period with strong to gale or even severe gale force winds driving spells of rain and showers across the UK repeatedly over and beyond Christmas , falling as snow at times over the hills.

 

NAVGEM tonight also replicates GFS and UKMO's trend of seeing the back of one spell of stormy weather as we exit Christmas and enters into another as a new storm system piles in from the North Atlantic post Christmas with renewed gales and heavy rain.

 

ECM keeps the unsettled and sometimes stormy weather going well beyond Christmas and towards the New Year with plenty of rainfall and showery interludes with cold enough conditions at times for some snowfall over the hills especially over the Christmas season itself.

 

The GFS Ensembles maintain no signals for any really cold weather anytime soon with the general trend for the very wet first week slowly giving way to less wet conditions for the South later in the run as temperatures maintain average uppers. The operational was a warm outlier at the end with it's warm uppers blowing in around an Atlantic high

.

The Jet Stream shows very little overall movement over the majority of the output time tonight though it does show some evidence of ridging North over the Atlantic around a displaced Azores High in the far reaches of the run.

 

In Summary there is a lot of very unsettled, wet and stormy weather to come over the next few weeks. Temperatures will fluctuate between a little above average during the rain bands to just below in the showery spells when some snow could be witnessed, especially over the hills and over the Christmas period itself. There is very little evidence of a reliable indication of the way out of this pattern with virtually no chance of any major changes this side of the New Year. The only evidence of change hinted at tonight is that the Jet flow be pushed back more towards the North again as High pressure builds again over Europe or the Azores though at 10-14 days out this theme will have to be maintained and built upon in future runs to gain any credibility.

[ANYWEATHER]

Im afraid same old ,same old with a repeat of the same weather we have had for a while, pointless looking for some sunstained  cold as the synoptics are not right! A positive NAO can provide some very interesting weather!!!!!    

[legritter]

Well certainly still interesting Model watching with plenty more Zonal weather over the coming week or so ,and a little light perhaps at the end of the tunnel regards some higher pressure perhaps attacking the arctic regions .Thanks to Mucka for helping me out with updating charts ,no luck yet i think i need a crash course on computers but will get there hopefully .Lets hope we all get Lucky over the Christmas period in any hvy precipitation especially if the Dice falls right .cheers 

[Stuie]

Most people will travel on Christmas eve , and it looks a lot worse at that point .. 

 

 

That`s why I said period Chris, not a great few days.

[BLAST FROM THE PAST]

With such a stormy, and I mean ';stormy pattern' do you really think the models have a complete handle on this?  This ain't 'normal' zoneality...we have wave after wave of fairly extreme weather here folks....expect a bit of interest 'upgrade' in FI

 

BFTP

[Summer Sun]

ECM ensemble for Christmas day has the low at 940mb

 

 

Then we get a 2 day respite

 

 

Before the next low sweeps in

 

 

Which gradually eases next weekend

 

 

We end unsettled but less windy than what next week will be at times

 

[IDO]

With such a stormy, and I mean ';stormy pattern' do you really think the models have a complete handle on this?  This ain't 'normal' zoneality...we have wave after wave of fairly extreme weather here folks....expect a bit of interest 'upgrade' in FI

 

BFTP

 

 

Hi

 

Funny enough the LW pattern we are in makes predictability much easier for the models. As many of us have said once you get into zonality, you can usually call it for weeks without even having to look at at a chart.

 

The ECM 5 day verification (500hPa) for 14 Dec 12z was 0.972, for 15 Dec 0z was 0.967. The 365 day average is 0.902 (since May 01 it has been 0.896)  so it is clear that the models have a good footing when a pattern like this sets in. In fact they are exceptional correlation stats.

Edited December 20, 2013 by i'm dreaming of...

[Newberryone]

With such a stormy, and I mean ';stormy pattern' do you really think the models have a complete handle on this?  This ain't 'normal' zoneality...we have wave after wave of fairly extreme weather here folks....expect a bit of interest 'upgrade' in FI

 

BFTP

As I suggested in an earlier post today this could become almost an historic weather period for such intense zoneality but I'm rather curious as to what's being suggested by the closing part of the above post. 

 

Anyone care to enlighten?

Edited December 20, 2013 by Newberryone

[nick sussex]

Just looking at the thickness values shown between the outputs the ECM is colder than the UKMO for late Xmas Eve and into Xmas Day, some interest develops as the flow slackens out across the UK.

 

The ECM looking at the Icelandic Meteo 6 hr steps does take a shallow feature ene across the se, ordinarily this wouldn't attract much interest given the 850 values but the thickness is really quite cold.

 

The detail this far out though is likely to change, these small features often come and go between outputs.

 

Further north some slow moving heavy showers wintry at times, the slackness of the pattern is really important if we're talking marginal snow. Upstream there are still some timing differences in terms of when that Newfoundland Low phases with the low near the UK, going forward this is quite important because the phase will push energy more ne/n towards Iceland.

 

The ECM at 168hrs upstream was an improvement in its previous outputs but the problem is really the orientation of the low near the UK, all the energy feeding ne, looking at the ECM spreads there is a cluster of solutions that do take low pressure further east rather than ne which could help if the upstream pattern is a little more amplified.

[tight isobar]

With such a stormy, and I mean ';stormy pattern' do you really think the models have a complete handle on this?  This ain't 'normal' zoneality...we have wave after wave of fairly extreme weather here folks....expect a bit of interest 'upgrade' in FI BFTP

fully agree thereBFTP. Its not a complete transistor events amd the modeled zoneality is far from non complex.It's a tweek or two from complete model re-look....

[lorenzo]

Here we go again, Santa in an F1 Sleigh this year. 70mph 10 meter wind speed into the NWest of the country.

 

Kicked off with a 245mph upper Jet.

 

 

 

 

[Mucka]

Latest NAE still has the snow risk for Yorkshire, NW England on Sunday.

 

Edited December 20, 2013 by Mucka

[swfc]

The jet is virtually in north africa at 120hrs on the 18z but we cant get any movement to the south east with the low and its obvious the secondry low will merge with it and move east  north east!!!

Edited December 20, 2013 by swfc

[Captain Shortwave]

Here we go again, Santa in an F1 Sleigh this year. 70mph 10 meter wind speed into the NWest of the country.

gfs_mslp_uv10m_eur_29 (1).pngviewimage.png

 

Kicked off with a 245mph upper Jet.

gfs_jet_200_natl_17.png

Hope the speed cameras are out, the government could make a killing from Santa here 

Sorry kids.

Oh models, I think that the weather for the rest of the month will be dominated by an upper trough close to or over the UK, basically unsettled with temperatures slightly below normal. I think the milder stuff in the output will get ironed out over time and be replaced by average temperatures interspersed with cool or chilly weather.

Edited December 20, 2013 by Captain shortwave

[Jason M]

A feature of recent outputs is the warmth over Europe. I was reading about the warmth in Siberia recently and looking at the charts for the next week or so it stays warm.

[Geordiesnow]

A feature of recent outputs is the warmth over Europe. I was reading about the warmth in Siberia recently and looking at the charts for the next week or so it stays warm.

 

Looking at the Northern Hemisphere charts, you can clearly see this compared to last year with most of the cold being bottled up in the Arctic, and it looks like Western Russia is going to get a "mlld" blast in the medium term so any cold just looks a long long way off. 

 

However the pattern is interesting and the contrast of severely cold air coming out of Canada with very warm moist air is certainly developing a deep low  pressure system with air pressure getting pretty low(940MB). I think the GFS is probably over doing the tightness of the isobars but the potential is certainly there into early next week. It is one of those where it would not be too surprising if the really strongest winds misses the UK all together but theres always a chance it could become an even more widespread event and perhaps even as tightly packed as the GFS shows. 

[swfc]

This current set up of severe areas of low pressure for me is the most severe i can remember for many a year in the uk.The lack of unsettled weather threw eastern and southern europe obv ties in but still.Really not my thing and getting tedious at best now!

[Cloud 10]

New fax charts for christmas eve and christmas day.

 

96 hrs..  120 hrs..

 

 

528 dam line covers much of the UK on Christmas day.

[UV-RAY]

HiFunny enough the LW pattern we are in makes predictability much easier for the models. As many of us have said once you get into zonality, you can usually call it for weeks without even having to look at at a chart.The ECM 5 day verification (500hPa) for 14 Dec 12z was 0.972, for 15 Dec 0z was 0.967. The 365 day average is 0.902 (since May 01 it has been 0.896) so it is clear that the models have a good footing when a pattern like this sets in. In fact they are exceptional correlation stats.

I disagree as the models have been woeful in the dotting the i's and crossing the t's for the last two weeks. It's all very well saying they've got the LW pattern right, but for this tiny speck of the NH what we've seen is far, far removed from conventional zonality and if we continue to see the jet digging further and further south then this opens the doors for something much colder down the line. Edited December 20, 2013 by Sceptical Inquirer

[swfc]

New fax charts for christmas eve and christmas day.

 

96 hrs..fax96s.gif  120 hrs..fax120s.gif

 

 

528 dam line covers much of the UK on Christmas day.

it also covers the uk sunday monday but in reality delivers nothing at ground level tbh

[Jason M]

18z is utterly dire. Zonal all the way. You could run that forward to march and it would still show the same.

This pattern is locked in hard and tbh its difficult to see how we exit from it. Obviously it's still only December but I'm starting to think a slightly cooler version of 1988 may be on the cards. I say slightly cooler because 1988 was extreme.

Let's see what the ensembles bring....