Model Output Discussion 1st Nov.2013

[Catacol]

The impact of the atlantic block, which was first picked up at the start of the month in some of the extended runs, is now entering the near reliable timeframe. These CPC charts let us down badly last December, but they are normally a very sound representation of the pattern and look good for early next week:

 

 

 

The pattern out in the pacific on the most recent ECM shows once again the impact of ridging near the aleutians forcing a more meridional pattern through the US, and in turn we have limited height rises over Greenland squeezing the westerlies very nicely

 

 

 

We also have a rise in wave 2 activity at 60N which will add a bit of vertical pressure on the vortex and help to make it wobble:

 

 

 

However... the strat is now well below average

 

 

 

and the extended GFS has the ridge flattened and back to square one by the 24th:

 

 

 

I think what happens next week is pretty much on target for the overall pattern this month. Westerlies are too strong at the moment, driven by a powering up vortex, and while the ongonig aleutian ridge gives us hope for sustained disruption and meridional moments I dont see anything sustained.

 

However, that aleutian high gives us much hope for the rest of winter, particularly if the strat is weakened as time goes by. There are plenty of forecasts seeing it as a semi permanent feature this winter with a consequent trough over the Eastern US. If the pacific pattern can sustain a strong meridional element then blocking in our part of the world is certainly possible probably more over Greenland than Scandy, but much is still to play for long term at this stage. I am still looking hard at the atlantic SST profile. I have a feeling in this scenario that we need the tripole signature to emerge. Without it I suspect the pattern will remain too flat over the atlantic to sustain blocking far enough north to give us a cold winter.

[Summer Sun]

Latest from Gibby,

 

All models show a Westerly flow over the UK with a moist and mild West feed across the South ahead of a cold front crossing SE overnight. Further North colder and more showery conditions look likely. This extends to all areas tomorrow with a cold night following as a ridge moves across all areas from the West. This holds through daylight hours of Wednesday with another decent day for most before a cold front moves quickly SE on Wednesday night bringing a spell of rain and followed again by a strong rise of pressure and a chilly North wind over Thursday and into Friday when an overnight frost could develop in places. Friday and the weekend sees a lot of cloud despite high pressure close to the UK. By Sunday a weak cold front ambling South in slack winds brings outbreaks of rain and drizzle in likely dull and overcast conditions with hill fog widespread and temperatures somewhat lower than of late.

 

GFS then shows next week becoming steadily colder as a Northerly feed develops with some rain or showers falling as snow on Northern hills. Pressure then builds across Scotland while the South sees Low pressure to the South and a strengthening and raw East wind with rain and sleet at times. At the same time the North would see frost and fog night and morning, possibly lasting all day in places. Rather cold here too. The end of the run sees more changeable and still rather chilly conditions as Low pressure lies close to or over the UK with rain at times and snow on hills in the North.

 

UKMO tonight shows a large High pressure to the SW and West of the UK with a slack and cooling North flow over the UK. Following rain clearing the South most areas would become dry and bright and rather chilly with frost and fog early and late in the South.

 

GEM shows the weather becoming colder next week as a cool West, NW then a cold Northerly flow is succeeded by Low pressure coming close to the East Coast later in the week and High pressure building to the NW. All this would mean unsettled weather with rain or sleet at times and snow over all Northern higher elevations and possibly over the higher hills of the South too with time. With slack cyclonic winds, low uppers and any clear skies overnight, this could allow for freezing fog and frost patches at times.

 

NAVGEM closes it's run next Monday showing High pressure ridging North through the Atlantic and allowing the door to be opened to the North over the UK with the prospect of a cold and showery North flow later next week with some snowfall in the North and widespread night frosts developing.

 

ECM shows a complex and confused pattern synoptically next week with the most likely result for the UK being a spell of rather cold and unsettled weather with rain at times with snow on Northern hills and patchy night frosts. With High pressure over the Atlantic and lower pressure over Europe the favoured wind flow would naturally be Northerly but never overly strong. 

 

The GFS Ensembles show rather cold and changeable conditions for the two weeks when taken as an average. A predominance of NW winds look likely and they would be none too warm at times though not dramatically cold. High pressure looks like being maintained down to the West or SW of the UK. Rain at times look likely for all areas especially through the second half of the run.

 

The Jet Stream is set to continue ridging North over the Atlantic and eventually returning Southwards across the UK later in the weekend and next week though weakening in strength.

 

In Summary there is strong evidence of a change to rather colder weather with the winds turning to a more Northerly direction. With pressure falling beyond the weekend there is a good likelihood of rain at times too next week and with temperatures on the decline some snowfall on Northern hills at least seems likely with the increased risk of frost and fog too if skies clear overnight.

 

http://www.norton-radstockweather.co.uk/Model-Analysis%282859336%29.htm

[Frosty.]

The GEFS 12z mean clearly indicates a colder spell next week and beyond with max temps struggling around 5 celsius. The mean shows a cold shot early next week then  high pressure builds in for a time through the mid range but this is followed by a reload of cold weather from the northwest, it then remains on the cold side for the rest of the run with temps struggling. The mean just provides the broad brush strokes and the outcome could easily be more potent than shown here, at the very least it will be turning colder and continuing generally unsettled with a risk of snow, especially on hills and frosty nights becoming more frequent.

[NO LONGER POSTING]

Please for the love of god can it remain charts like this until we get the first "event" or hell will break loose in here..... Just saying  

 

Lovely looking charts mind.... 

[Tom Jarvis]

well just looking through all of the models available on meteociel they are all showing something cold in the 180h timeframe. I don't know if that has happened before

[BLAST FROM THE PAST]

!!!

 

Yep, its almost spot on

 

BFTP

[Methuselah]

Yep, its almost spot on

 

BFTP

We'll hold you to that, Fred!  

[BristolBlizzard]

!!!

[BLAST FROM THE PAST]

We'll hold you to that, Fred!  

I wish I could promise it!!!!

 

BFTP

[Weathizard]

Looking closer to the 'reliable' I prefer the 168hrs chart in regards to potential as the falling pressure at 240hrs around Southern Greenland looks a concern to my eyes, there appears to be quite substantial disruption around the polar vortex already even at this stage of winter (late autumn) which is not unusual but for long term prospects I do not want that PV placing itself over that region.

A complex week of model watching coming up I feel.

Edited November 11, 2013 by Weathizard

[BLAST FROM THE PAST]

So then, even though its November, even though we should traditionally see strong westerly influence over the UK

we get our first early taste of -8/-9c's into Scotland....

 

The projected cold attack from the north is gathering pace...

 

at 216 we sit in a lull....

http://www.meteociel.fr/modeles/ecmwf/runs/2013111112/ECH1-216.GIF?11-0

 

 

Also notice the low over ITALY- a very snowy pattern for the alps etc- also great news to see heights dropping in Europe

 

 

S

 

Hi Steve

My post the other day highlighted that area as an important ingredient to possible colder development.  I agree totally

 

BFTP

[radiohead]

JMA at T192

 

[Frosty.]

There are some very wintry GEFS 12z perturbations tonight, some where max temps are struggling to get much above freezing at times from next week onwards, a few bordering on ice days and snow would feature at all levels on many of these charts in various timeframes. The general idea from these charts is a reloading cold pattern from the northwest with just brief lulls in between, there are lots of other charts I could have posted which show near misses and others which take longer to evolve into the finished article but not many duffers in there, they are mostly going cold with some polar maritime and arctic blasts, I think it's GAME ON FOLKS. 

[Summer Sun]

ECM ensemble shows -5 850's getting into Scotland at days 8 and 9

 

 

Day 10 shows them pushing away

 

[damianslaw]

The models continue to suggest a notable cool down as we move into the second half of November - a theme for a number of days now.

 

It does now seem heights will build sufficiently over the mid atlantic stopping the flow of the atlantic on its westerly trajectory by the weekend.

 

Not surprised to see ECM showing the very cold uppers - there is a mass of very cold arctic air lurking to our north but its far from certain just how cold things may get.

[garbagebags]

The models continue to suggest a notable cool down as we move into the second half of November - a theme for a number of days now.

 

It does now seem heights will build sufficiently over the mid atlantic stopping the flow of the atlantic on its westerly trajectory by the weekend.

 

Not surprised to see ECM showing the very cold uppers - there is a mass of very cold arctic air lurking to our north but its far from certain just how cold things may get.

 

I've been saying for weeks that the raging PV since start October has been a good thing. Now at least we have decent cold to unleash. 

[garbagebags]

Seat belts on for the 18z 

[bluearmy]

as has been said, the key to this becoming more than a toppler remains low heights becoming established over europe. that is a win win (or lose lose of you are gavin) for us to be cold either via an amplified atlantic or an extended ridge over the top of the euro low.  intriguing isnt it ?

[garbagebags]

How rare is it to have at least 4 models in complete agreement at day 7? Is that not fairly rare?

[mpkio2]

There are some very wintry GEFS 12z perturbations tonight, some where max temps are struggling to get much above freezing at times from next week onwards, a few bordering on ice days and snow would feature at all levels on many of these charts in various timeframes. The general idea from these charts is a reloading cold pattern from the northwest with just brief lulls in between, there are lots of other charts I could have posted which show near misses and others which take longer to evolve into the finished article but not many duffers in there, they are mostly going cold with some polar maritime and arctic blasts, I think it's GAME ON FOLKS. 

What delicious looking Eye candy!!

 

I've been saying for weeks that the raging PV since start October has been a good thing. Now at least we have decent cold to unleash. 

Agreed. Its better to have cold to tamp into than to have none at all. Hopefully the pacific ridge can push some warm air into the artic, causing havac up there, leading the PV to become disturbed and, again hopefully, set up a nice block in the right position for the UK. Fingers crossed, eh?

Edited November 11, 2013 by mpkio2

[Summer Sun]

Someone earlier on was asking about Ian Fergusson and MOGREPS, whether his tweet is based on that I don't know but he tweeted this around 20 mins ago

 

Growing model consensus on a chilly story into next week, albeit a pretty standard cold snap, in broad scheme of things, for late November.

 

https://twitter.com/fergieweather

[bluearmy]

How rare is it to have at least 4 models in complete agreement at day 7? Is that not fairly rare?

 

are they in complete agreement ? i guess it depends which part of the chart you are concentrating on. are we talking broad upper level pattern or more detailed surface pressure ?  i suspect you are alluding to the change in the atlantic and the fact that all four main models are picking it up at the same time. its not so rare although over the past year, there have been too many occasions when some of them have really let themselves down.  dont worry, i'm sure the broad agreement wont last too long! 

[Snowman.]

 

!!!

 

Brilliant! 

 

NAVGEM is a beauty as well.

 

[Frosty.]

Another UPGRADE folks, tonight's Ecm 12z ensemble mean is even colder and more wintry than the 00z and last night's 12z, cold air sweeping down from the northwest during next week, once the PFJ sweeps south, we remain on the cold side of it and there is a risk of it turning more arctic with a risk of snow just about anywhere, and frosty nights. If the mean carries this on for a few more days we are home and hosed for a much colder outlook.........BANK   

[Newberryone]

The impact of the atlantic block, which was first picked up at the start of the month in some of the extended runs, is now entering the near reliable timeframe. These CPC charts let us down badly last December, but they are normally a very sound representation of the pattern and look good for early next week:

 

 

 

The pattern out in the pacific on the most recent ECM shows once again the impact of ridging near the aleutians forcing a more meridional pattern through the US, and in turn we have limited height rises over Greenland squeezing the westerlies very nicely

 

 

 

We also have a rise in wave 2 activity at 60N which will add a bit of vertical pressure on the vortex and help to make it wobble:

 

 

 

However... the strat is now well below average

 

 

 

and the extended GFS has the ridge flattened and back to square one by the 24th:

 

 

 

I think what happens next week is pretty much on target for the overall pattern this month. Westerlies are too strong at the moment, driven by a powering up vortex, and while the ongonig aleutian ridge gives us hope for sustained disruption and meridional moments I dont see anything sustained.

 

However, that aleutian high gives us much hope for the rest of winter, particularly if the strat is weakened as time goes by. There are plenty of forecasts seeing it as a semi permanent feature this winter with a consequent trough over the Eastern US. If the pacific pattern can sustain a strong meridional element then blocking in our part of the world is certainly possible probably more over Greenland than Scandy, but much is still to play for long term at this stage. I am still looking hard at the atlantic SST profile. I have a feeling in this scenario that we need the tripole signature to emerge. Without it I suspect the pattern will remain too flat over the atlantic to sustain blocking far enough north to give us a cold winter.

Can't begin to tell you all how disappointed I was this afternoon to hear one of the news stories on the radio relating to the prospects of a cold Winter being a non starter. It would appear that the Irish meteorological service, Met Eireann are not buying into this coming season as being anything other than average or indeed ordinary.

As we all learned a hard lesson from last Dec when the beast from the east failed to materialise, perhaps we need to generally lower our expectations. 

 

http://www.irishexaminer.com/breakingnews/ireland/no-big-freeze-this-year-says-met-eireann-612901.html

 

Needless to say I'm hoping Gerald Fleming of Met Eireann has got this one totally wrong 

Edited November 11, 2013 by Newberryone