Model output discussion - 5th December 2016 - Into Winter we go

[Singularity]

2 hours ago, knocker said:

I'm not sure whart time frame you are considering but there seems to continuing indications of the trop vortex consolidating over N. Canada with height rises adjacent to the UK which seems also to be favored in the lower Strat.

You're quite right regarding trop. and lower strat. as well come to think of it; I was looking at 10 hPa but forgot to mention that important detail.

Recent GFS runs for the 30 hPa level have been unusually inconsistent in the 10-16 day range - reflecting the waxing and waning of the Eurasian blocking signal from run to run.

I must say, I'm surprised just how much more progressive the models have trended today; it's a particularly strong reaction to the adjustment in tropical prognosis. Obviously if the projections for MJO activity shift again, so may the model output for next weekend. Though even with these ideas in mind, I find the 12z ECM extraordinary in how much mobility it produces from the eastern- N. Atlantic all the way across to central Asia.

[knocker]

Not to spend too long on the anomalies this evening as there is not much new to say. Still the differences  in the 6-10 range essentially down to a different interpretation of the configuration of the complex vortex area Canada/Greenland and associate Atlantic trough, which also impacts  the orientation if the HP to the east.  The ecm is much less amplified than NOAA or the GEFS  with quite weak high pressure to the east. This could well push the jet to run slightly more east of north and thus surface lows track further south but it is these details that the det models will need to sort in the next couple of days because, as we have already seen this evening, the pattern has the potential to generate a nasty storm. As it is we are still looking at a wet and windy period.

In the 10-15 time frame they are all looking to retrogress the vortex to Canada and the weakening trough to the western Atlantic and to build heights in the east but all by different degrees and convictions so this still remains a watching brief.

Edited December 17, 2016 by knocker

[phil nw.]

The last 3 days of this mundane,quiet spell is upon us with the models on day 4 indicating strengthening south westerlies extending right down the UK before Christmas.

The UK chart at day 4 

The worst of the wind and rain seems more likely in the north at first but by Christmas most places will be under the unsettled and windy conditions with an angry looking Vortex just to the north.

ECM mean at day 8(Christmas day)

 

I don't think we can rule out some snowfall,especially on higher elevations further north when we get some polar air in the mix as the jet moves further south but at this range surface conditions are subject to change.

It isn't want many of us were hoping for but it's no surprise given the upward trend in the Stratospheric zonal winds speeds and the the gradual removal of the amplification of the Atlantic pattern.Normally in these zonal patterns the north of the UK is more favoured for any wintry conditions behind any cold fronts but these tend to be fleeting spells with pattern so mobile.

It looks like it will be towards year end before there is a chance of a change with later gefs still showing the Greenland trough receding and some rise in pressure from the south.

 

[Dennis]

Its time to see the result for next week..... or we see heavy wet weather and mild or some great things are possible for cold and easterly

Many have there eyes on the Lows from the west 

[Cheshire Freeze]

2 hours ago, Summer Sun said:

JMA and ECM pretty much in agreement on the depth of the low the position of it they are not

Wow...that ECM chart. Some serious potential for disruption if that comes off. 

Even the 12z GFS- you're looking at 60-70mph fairly widely here

Edited December 17, 2016 by CreweCold

[Cheshire Freeze]

8 minutes ago, feb1991blizzard said:

Disruption? not sure how, it will just barrel straight through, theres no block to the NE to force it south.

Some of the worst storms we've seen in this country have been where lows zip through WSW-ENE as shown with the ECM. A la Boxing day storm 1998 for one.

The GFS scenario is perhaps more extreme in terms of longevity as a severe gale SW'ly sits over the UK for hours

[Scandinavian High.]

 Unsettled  over Christmas period then a battle low to west high to east. The high will win battle run up to new year with a cool south easterly .

[Derbyshire Snow]

3 days since my first post this Winter and as expected nothing really changed and its very hard to be optimistic as regards a cold wintry spell in the near future. Strong high pressure over Russia and Eastern Europe holding its ground   and very reluctant to extend westwards.The position of this  means  that lows  crossing  the Atlantic reach a wall  near our shores and push north or north east leaving us in sometimes  quite an unstable but generally cool flow with the potential of some severe storms as the Russian  high weakens and potential rapid cyclogenesis . The main culprit of course is the jet stream and unfortunately its starting to show firing on all cylinders.

jetstream over North America today, thats some force heading in to Atlantic

 jetstream over North Atlantic forecast Christmas Day. Need one say more!

OK how do we get cold in this situation and its not easy.

My thoughts:

1. We need the Siberian High to push North westwards towards Scandinavia and  hopefully deflecting a substantial low south east in to Europe thus bringing in some very  cold sustained north easterlies. Even better if it would link up to a Greenland high. Highly unlikely because of this jet stream strength

2. The Siberian high to move away eastwards rapidly allowing depressions to move right through the British isles in to Northern Europe and Scandinavia allowing hopefully heights to develop in the North Atlantic. This could bring substantial northerlies to the UK, however topplers most likely as well. Unfortunately the depth of cold in Siberia is unlikely to dissipate enough, and  to be honest looks set there for the winter

3. Or the best scenario a SSW  which could bring a dramatic change of weather in a relative short space of time.

Lots of interest however later next week and hope the storm at present forecast for Christmas Day does not materialise. Possibity of snow on Northern Hills but nothing special

 

 

[Man With Beard]

Well we often have a moan about the GFS in FI, but that weird little cold pool for Tuesday was modelled several times at as much as D10, and is now hitting the south coast at T60 - just a short distance from developing into a snow bearing cold pool, had the Atlantic been delayed say 24 hours. I recall it being first onto the storm in November too. Both situations looked wacky at the time. I'm beginning to think that when the GFS does something wacky between T200-T300, it's worth watching because it may that modelling "eureka" moment.

[Gael_Force]

24 minutes ago, abbie123 said:

 Unsettled  over Christmas period then a battle low to west high to east. The high will win battle run up to new year with a cool south easterly .

There will be many changes by the time we get to new year but the charts you show are a pressure anomaly and do not show the wind direction. 

A variety of southerly options there.

[Sky Full]

Dont worry, my long suffering weather fans, I am assured that January will be delivering the required goods and we don't have long to wait.....

 

. 

It's foretold by the CFS so it MUST be right?

erm,  I have missed a few lessons in here over the last couple of terms so I might have got that wrong.  I'll go and do some more homework....

[Scandinavian High.]

2 minutes ago, Gael_Force said:

There will be many changes by the time we get to new year but the charts you show are a pressure anomaly and do not show the wind direction. 

A variety of southerly options there.

Has you can see the high is to the east maybe slightly north so yes a southerly south easterly.

[Iceberg]

18z gfs coming out for the Christmas period and shows how small changes can have bigger effects. 

[stewfox]

5 minutes ago, Sky Full said:

Dont worry, my long suffering weather fans, I am assured that January will be delivering the required goods and we don't have long to wait.....

 

. 

It's foretold by the CFS so it MUST be right?

erm,  I have missed a few lessons in here over the last couple of terms so I might have got that wrong.  I'll go and do some more homework....

30 November post ..

""""According to the GEFS 6z mean it looks anticyclonic, at least for the southern half of the uk for the next 10 days or so but with the fine weather across the north gradually being eroded with more atlantic influence, towards mid Dec it becomes generally unsettled across the uk but this goes completely against the met office update.""""

 

Of course your right 

[January Snowstorm]

Christmas forecast proving a big elusive at the moment.

The over riding theme however is that it'll come increasingly unsettled as we near the holiday period.

Snow less likely now though a stormy big day is quite possible! 

[blizzard81]

No wonder it is so quiet in here this evening. The model runs have been abysmal today for coldies. The last thing I was expecting was a stormy spell during Christmas. NONE of the long range forecasts (and that includes the met)  even hinted at such a possibility and that is a fact.

Edited December 17, 2016 by blizzard81

[Frosty.]

13 minutes ago, stewfox said:

30 November post ..

""""According to the GEFS 6z mean it looks anticyclonic, at least for the southern half of the uk for the next 10 days or so but with the fine weather across the north gradually being eroded with more atlantic influence, towards mid Dec it becomes generally unsettled across the uk but this goes completely against the met office update.""""

 

Of course your right 

That sounds familiar, is that what I posted 

[stewfox]

4 minutes ago, Frosty. said:

That sounds familiar, is that what I posted 

Apologies should have referenced you , a benefit of doing the odd 24 hr summaries but interesting.

Seems to be more of a mix out of PM up to boxing day, now 'waiting' to see anything better post that on 18z

[cyclonic happiness]

5 minutes ago, blizzard81 said:

No wonder it is so quiet in here this evening. The model runs have been abysmal today for coldies. The last thing I was expecting was a stormy spell during Christmas. NONE of the long ranges forecasts (and that includes the met)  even hinted at such a possibility and that is a fact.

Even the storm seems to be going away for Christmas day, We'll probably end up in anticyclonic gloom again.

I swear the models over the past few winter, have been the worst I've ever known in over 14 years of model watching

[nick sussex]

I think the thread is stunned into silence. Truly dreadful output from a cold perspective with the  belt of high pressure over Europe pumping warm air all the way from near the Canary Islands right into Russia. Thankfully I have friends arriving tomorrow for Christmas and will have less time to spend watching this wretched output day in and day out!

[Rocheydub]

1 minute ago, cyclonic happiness said:

Even the storm seems to be going away for Christmas day, We'll probably end up in anticyclonic gloom again.

I swear the models over the past few winter, have been the worst I've ever known in over 14 years of model watching

Surely you mean the weather has been the worst in 14 years? Unless you believe in the models creating the weather? :-)

That storm is pretty much solid across all models, postage stamps, GEFS etc. Worrying that it could destroy a lot of people's Christmas!

[Frosty.]

1 minute ago, cyclonic happiness said:

Even the storm seems to be going away for Christmas day,

 

That's good news as most of us don't want a storm disrupting the busy christmas period but I am hoping for some cold zonality for the first time this winter, which is what some of the models have shown today.

[karyo]

Southwesterlies start at abut 70 hours from now and then continue until the depths of FI in the 18z!

It looks like we will be stuck in this for a while.

[blizzard81]

1 minute ago, nick sussex said:

I think the thread is stunned into silence. Truly dreadful output from a cold perspective with the  belt of high pressure over Europe pumping warm air all the way from near the Canary Islands right into Russia. Thankfully I have friends arriving tomorrow for Christmas and will have less time to spend watching this wretched output day in and day out!

With all the positive signals towards a cold start to winter, this has to be the most depressing and disappointing start to winter since I started looking at the model output 13 years ago.

[Dennis]

Next year GFS18z