Model Output Discussion - The Start Of Winter

[Dorsetbred]

Apologies for not showing charts but my pc skills are not upto much but one thing that seems consistent in all models is the Azores High not moving much in next 240hrs.I know it is only one aspect of things falling into place to eventually get cold but in the FI it does pull further West in last few frames of GFS and if this continues to become a trend maybe this could trigger a pattern change as the likes of S Murr,Tamara are indicating in the last few days of the year. Sorry if I have got this all wrong but until this happens and/or Heights rise to our North we are in the same pattern for next 10 days which although a bit monotonous is still fascinating to watch how it all evolves and maybe, just maybe, may result in a pattern change which would result in a lot of happy people on this forum. I hope Ian F"s comments on the future firm up and turn into reality lol

It in interesting from another perspective, that of stability at this time of year. Looking at the charts and seeing stability out to 240h is not usual at this time of year, certainly compared to last year, for example. 

So we have a period of stable and consistent weather for the 240hrs plus, let's see how we go from there.

[Ali1977]

The ECM at T240 looks poised to bring some cold to the UK, even in time for XMAS day. Just need some height rises to the West of Greenland and it would open the arctic flood gates - I think.

[legritter]

Erm, to be very clear: OPI hasn't been peer-reviewed. To say it's 'poor' is pre-empting rigorous independent assessment and unfairly dismissing work by it's authors. It may or may not be onto something, but for now we can't assess this in any informed fashion, so it's not factored into key seasonal prognostics.

I will try and find out where i read a good article [opi ] and something to do with the polar vortex being possibly broken up and not staying for long in one place this winter season .very interesting times on the cards i think and each day throwing up new possibilitys ,but as usual its along hard slog getting good winter synoptics into the good old UK ,but its happened on thousands if not more occasions as history will tell you ,well thats my big straw for now .

[minus 9]

Dont post to often as my knowledge is just about average. But talk about rinse and repeat, im sure ecm at 144 is nearly exactly the same as yesterday's chart.

[phil nw.]

No real surprises from the 12z runs.

Continuing rather cold and changeable much of the time with the odd milder day as frontal systems cross the UK bringing changes in air masses from polar maritime to something less cold from the mid-Atlantic.

It looks like the Scottish Highlands will see further snowfall with perhaps some wintry showers around at lower levels in the north at times.

 

The ongoing spread of low pressure across Greenland to Scandinavia means any Atlantic ridging will continue to be transient  but at least it gives us those colder shots from the north west.

[Methuselah]

So how about - anywhere between rather cold and rather mild, on any particular day? Average or what?

[TEITS]

So your forecast for next week is mild and to back it up you have posted a snapshot of the mildest chart you could find? 

Average CET for next week should come in around average and here is UKMO for Tuesday, another misleading snapshot of next weeks weather.

 

 

If you read my post correctly I was merely replying to the comment that "mild weather is pushed into F.I" and illustrated this isn't the case by posting the Wednesday chart. I also stated about the return to cold next weekend.

 

12Z ECM clearly shows my post was accurate.

 

+96 Mild next Wednesday

http://www.wetterzentrale.de/pics/Recm962.gif

 

+168 Colder spell at weekend.

http://www.wetterzentrale.de/pics/Recm1682.gif

 

+216 return to mild.

http://www.wetterzentrale.de/pics/Recm2162.gif

 

+240 Could cold return in time for Xmas?

http://www.wetterzentrale.de/pics/Recm2401.gif

 

No selective charts from me. Just an honest unbiased summary of the output.

[Cloud 10]

One cannot get away from the fact that some very mild nights are forecast thus skewing the accumulated five day anomalies - what is surprising is that the month to date plus all these (next seven day) milder interludes should still amount to below average in my native turf and just on average in the south.

 

 

Source is a useful page for looking at reanalysis and forecast of temperature data.

 

http://www.karstenhaustein.com/climate.php#forecast

 

 

The 850mb temperature anomaly for the first 8 days of December also highlights the mainly 

below average theme so far this winter,and looks like those cold anomalies moving a bit further East

as we head into 2015.

 

[Frosty.]

Great to see 522 & 528 dam thicknesses making visits to the uk on tonight's Ecm 12z op run, it's like saying hello to a friend who you haven't seen for a few years. I won't bother hiding my bias at this time of year, I love cold weather and want my snow dammit!! and generally the models today show the balance tipped in favour of rather chilly and wintry incursions from the NW during the next few weeks and only fleeting milder Tm intrusions associated with wet and windy spells as we slip and slide further into a winter which promises a lot more than that feeble effort last time.

Edited December 13, 2014 by Frosty.

[Banbury]

Great to see 522 & 528 dam thicknesses making visits to the uk on tonight's Ecm 12z op run, it's like saying hello to a friend who you haven't see for a few years. I won't bother hiding my bias at this time of year, I love cold weather and want my snow dammit!! and generally the models today show the balance tipped in favour of rather chilly and wintry incursions from the NW during the next few weeks and only fleeting milder Tm intrusions associated with wet and windy spells as we slip and slide further into a winter which promises a lot more than that feeble effort last time.

Great posts again Karl

[MR EXTREMES]

I would like to welcome everyone to the model thread where weather and models talk to each other and conspiring against Us deprived Prozac cold junkies to erupt into a warm vs cold battle !!!!

Anyway back to the models pretty much the same as the last few days or even the last two weeks!.

of coarse the models do struggle with outputs beyond 144 even 96 hrs,

beyond 144 is a pretty long time in the weather world.

I'd expect to see some changes around or after Christmas the models are sniffing something.

I'd hide behind the sofa for at least the next few days.

[snowking]

Looking slightly further ahead beyond the current is it milder/colder than average debate (FWIW - ECM 12z would have us somewhere around average overall with a succession of short milder/colder periods vs. standard climatology), we have been seeing increasing example of this in recent runs:

 

 

Can anyone spot the similarities? The main trend is to push the majority of the vortex energy towards the Eastern Hemisphere. What is the significance here? Well it could be that there is a disconnect between the Troposphere and Stratosphere right now, but it may also be a reaction to successive runs showing this:

 

 

A very clear signal for an attempted Wave 1 attack, trying to push the vortex away from its home over the pole and over toward the E. Hemisphere. The most significant thing here is that it gives credence to the idea of upstream amplification across the US/Canada. We have seen plenty of discussion of this towards the xmas period and beyond over the last couple of days and the stratosphere is certainly supportive of this idea.

 

To this extent, just taking a look through the ECM EPS stamps over the CONUS, an encouraging number of them support the idea of ridging just off the Eastern Seaboard, and a cut off low potentially amplifying the ridge, around the xmas period.

 

Nothing too prolonged showing cold wise but enough to keep everybody interested for now and do not assume that anything beyond day 10 is set in stone with a lot of different solutions on offer upstream. The sort of pattern that could be priming itself is one which could offer up some eye candy at a much shorter range than one might expect and you can certainly start to see where the Met Office may be seeing some interest in supporting GloSea5 scenarios beyond the 15 day period, especially with the re-establishment of a stronger Aleutian low.

 

It looks as though we are about to see a renewed MJO signal coming in to play through the second half of this month too:

 

 

If this is to overwrite the global circulation once again then let hope we can drive it towards Phase 7 to set us up for some fun in January. Certainly this experimental OLR forecast sends us towards phases 6/7 in to Early/Mid January:

 

 

SK

[ANYWEATHER]

Lets get next week in some sort of order, well weather permitting! A rather cold start to the week, then midweek milder then colder to finish late week into the weekend, of course the devil will be in the detail....

[Penrith Snow]

So we go from ultra mild models this morning to colder ones thus evening but all really with the same theme of west/ northwesterly flow bringing alternating spells of colder/ milder weather.

In other words exactly what the MetO outlook has been saying for weeks!

Sometimes I wonder why I spend hours and hours in winter watching the various model runs when the MetO summaries it without the hype in a few sentences each day!

We really do have the best weather forecasting organisation in the world.

Andy

[nick sussex]

Encouraging to see cross model agreement on some renewed amplification over the USA, a bit too far out though to be sure of but this could deliver some colder conditions over Christmas.

Looking at the ECM longer range ensembles a colder cluster developing around that time , I think the question mark is whether we can get those low heights away from Greenland to allow good retrogression of the Azores high.

[Penrith Snow]

Without copying snow kings excellent post I have to agree.

Despite some very dodgy output recently for the UK sector mostly due to the AH the wider NH view is one that pushes the PV into Russia, as per Steve Murrs avatar.

In the long term a displaced PV can only be good news.

Andy

[knocker]

So what do the anomalies have in store tonight.

 

The NOAA 6-10 has a broad area of weakfish low pressure Greenland east to Scandinavia which intrudes on the northern parts of the UK. Underlying this is the Azores high. Upstream not a huge amount of amplification with HP NE North America and SE Pacific and LP Alaska.

The 8-14 weakens the LP north of the UK a tad and moves it slightly east which allows a very weakfish positive pressure over the Atlantic linking to the NE American high. Also more influence from the HP in the eastern Pacific.

 

There are some variations with the GFS and ECM but they are on the same page.

 

This would seem to indicate no major changes in the overall pattern with LP to north and and probably a little further east with Azores HP to the SW maybe moving a tad east, So generally a continuation of the zonal flow.

 

Further down the line indications of an Alaskan ridge, LP N. America and HP from Greenland ridging south mid Atlantic and a more meridional flow. The evolution from here may be interesting.

 

Charts courtesy weatherbell

Edited December 13, 2014 by knocker

[damianslaw]

Most noteworthy aspect of today's models is the suggestion of a more 'amplified' flow over Canada and USA which as people have said enables a ridge to form over NE USA seaboard and cut off low scenario to the SE of USA - this can been in the GFS output just before Christmas. Such developments would enable the azores high to ridge sufficiently northwards towards Greenland locking the trough into place to our NE.

 

All eyes on developments on the other side of the atlantic over the next few days.

[Mucka]

If you read my post correctly I was merely replying to the comment that "mild weather is pushed into F.I" and illustrated this isn't the case by posting the Wednesday chart. I also stated about the return to cold next weekend.

 

12Z ECM clearly shows my post was accurate.

 

+96 Mild next Wednesday

http://www.wetterzentrale.de/pics/Recm962.gif

 

+168 Colder spell at weekend.

http://www.wetterzentrale.de/pics/Recm1682.gif

 

+216 return to mild.

http://www.wetterzentrale.de/pics/Recm2162.gif

 

+240 Could cold return in time for Xmas?

http://www.wetterzentrale.de/pics/Recm2401.gif

 

No selective charts from me. Just an honest unbiased summary of the output.

 

Okay. Suggestion and inference. Nothing wrong with your assessment if no emphasis on mild as that is not the dominant theme.

 

Christmas period looks hard to pin down at the moment but no sign of deep cold certainly.

 

We're due a more exciting Op from GFS and what better time than the the weekend pub run to deliver?

Edited December 13, 2014 by Mucka

[Tom Jarvis]

168 gfsp chart is quite interesting with a nice northerly and better ridging

Unable to post chart as on phone

[Ali1977]

GFSP showing a much more potent Northerly next weekend

Edited December 13, 2014 by Ali1977

[knocker]

Just out of interest had a quick look at the GEM

 

It does have HP NE America/Greenland it keeps the main ridging from the Azores so no retrogression but more an eastward movement accompanied by a weakening and movement east of the norther trough. Things are afoot. Place your bets,

Charts courtesy weatherbell

Edited December 13, 2014 by knocker

[Geordiesnow]

Lets get next week in some sort of order, well weather permitting! A rather cold start to the week, then midweek milder then colder to finish late week into the weekend, of course the devil will be in the detail....

 

Indeed and obviously the postioning of the jet stream will depend just how far South any PM air gets. Looks like the -10hpa could hit the shetland isles on Monday according to the GFS, a brief affair mind. 

 

It does look like Wednesday will be the day where it will be widespread mild with Tuesday being the transition day, how quick this mild air comes in on Tuesday is still open to a little bit of doubt. 

 

I personally like too see the variation and I'm certainly finding this month more interesting wise than November. Just ashame so far these cold shots don't have a bit more oomph about them in terms of getting more in the way of lowland snowfall mind. 

[Blessed Weather]

........Further down the line indications of an Alaskan ridge, LP N. America and HP from Greenland ridging south mid Atlantic and a more meridional flow. The evolution from here may be interesting.

 

Hi Knocker. I don't always agree with your posts but tonight I think your analysis (in both posts) is spot on. The anomaly chart for 28th Dec (copied below) is indeed very interesting, suggesting the UK could be in a bitter Northerly flow if it verified. Of course, it's a very long way off but it does tally with the thinking of several posters on here that the first real cold spell will arrive from the North. Softly, softly but is a trend developing?

 

[knocker]

Never mind the northerlies for next weekend see if you can follow track of the low that ends up in the North Sea and deepens quite rapidly. Could bring some moderate snow in NW Scotland.