Model Output Discussion 29th December - Into mid-Winter.

[jvenge]

The 06z is handling the colder air a little differently over eastern Europe in the day 5 range, as compared to the 0z. Perhaps this will put to bed the who is right for me this weekend between the ECM and GFS, as the differences for Saturday were quite pronounced. 

[joggs]

13 minutes ago, radiohead said:

Another shot of cold air at T204 on the GFS. ECM was showing something similar too.

Too much energy barreling over the top of the high for anything sustained imo.

Edited January 4, 2017 by joggs

[Weathizard]

Can't get excited by any of the models this morning, just standard winter fayre!

Even with low pressure over the med we still seem to get the worst outcome possible with the Azores slug sliming all over us as usual and the lows barrelling through.

Edited January 4, 2017 by Weathizard

[booferking]

Lowered heights in med better chance of Easterly later on.

[Alekos]

Just now, booferking said:

Lowered heights in med better chance of Easterly later on.

Another great chart for us here, though quite far away in the time scale ! I think the Scandernavia High would go South after that 

[Seasonality]

2 minutes ago, jvenge said:

The 06z is handling the colder air a little differently over eastern Europe in the day 5 range, as compared to the 0z. Perhaps this will put to bed the who is right for me this weekend between the ECM and GFS, as the differences for Saturday were quite pronounced. 

And if the run verifies it will be a decent January cold spell. Southeast Europe does particularly well staying sub zero throughout and further north in central Europe, say from Eastern Poland, is similar barring a brief milder incursion of around 24 hours, which even then only raises surface temps just above zero. 

[radiohead]

Proving really hard to shake that high. It's there right to the end of the run...

[Nick F]

8 minutes ago, booferking said:

cold Lowered heights in med better chance of Easterly later on.

06z GFS op ridges NE as the deep Euro trough to our E and NE cuts off from the upper westerlies toward Greenland/Iceland, so we end up with surface high pressure from the Azores linking with surface high pressure over NW Russia.

However, IMO Azores ridging NE to link with high pressure over Scandi is never great for sustained and progressively cold E/NE flow - particularly with a strong 500mb vortex close to the NW over Iceland and Greenland, so fairly swiftly the unsettled westerlies return.

The Euro trough is a step in the right direction and will direct the upper flow NW to SE keeping us flirting with cold NWlies with the ocassional brief Nly shot, whether the Euro trough will cut-off from the upper westerlies to allow pressure to build NE over the UK is uncertain though ...

Edited January 4, 2017 by Nick F

[northwestsnow]

6z highlights the contiuning problems well.Anything from the north/ north west will be transitory until we see a relaxation of the bloody northern jet!Even when we eventually see that other pain in the rear ( euro high) depart we still cannot get any meaningful retrogression in the Atlantic.

So, glass half full we may see a toppler and cold air but by the time its getting established the azores high will kill off any associated precipitation.

Still looks carp for any sustained cold imho..

[Alekos]

3 minutes ago, northwestsnow said:

6z highlights the contiuning problems well.Anything from the north/ north west will be transitory until we see a relaxation of the bloody northern jet!Even when we eventually see that other pain in the rear ( euro high) depart we still cannot get any meaningful retrogression in the Atlantic.

So, glass half full we may see a toppler and cold air but by the time its getting established the azores high will kill off any associated precipitation.

Still looks carp for any sustained cold imho..

Hi the Northern jet strength has been the main reason I see for us getting so much cold and snow for last 20 years

[Nick F]

If it's not the Euro slug preventing any sustained deep cold and wintry weather setting in across the  UK, the strong Azores ridge is sitting there ready to keep the deep cold at bay too on GFS, a product of the deep 500mb vortex over Greenland/Iceland and strong N Atlantic jet.

At least 00z ECM + EPS does retrograde the sub-tropical Atlantic high to the other side of the N Atlantic which keeps the cold NW to SE flow, though with little amplification out to day 10, any sustained wintry weather away from the north seems a pipe dream for now.

[Polar Maritime]

Ok a few post have gone, Anything the Model Outputs are showing can be discussed in here. Where-ever you are/or discussing in the world.

Edited January 4, 2017 by Polar Maritime

[Summer Sun]

 

[nick sussex]

Looks like we might move from spam fritters to rump steak but still no sign of fillet on the menu.

Because of the recent weeks of utter tedium the output isn't so bad but still shows no sign of delivering anything that suggests getting the sledge out or having a sick day( sorry can't come in because I want to play in the snow)!

Relentless energy spilling east from the PV means its a case of windows of wintry opportunity rather than the window remaining open for any length of time.

The GFS continues to play around in its FI with trying to drop the low south with hints of some easterly flow but too far out to be anything but just wishful thinking at this point.

Looks like the ECM ensembles do have some similar solutions with day 11 onwards showing some more east/ne wind clusters so perhaps a small chance but given the winter so far a very low probability.

Overall the outputs aren't filling me with much joy but at least theres more sign of the Euro slug high at least edging west for a time although I won't believe this until its shown in the more reliable timeframe.

[Interitus]

6 hours ago, Steve Murr said:

CFS operational &control now going for a SSW late Jan-

S

Two CFS perturbations go for an SSW in February, using the reversal of wind as central date as is the general custom, the other perturbation and control show no SSW into March. The CFS and GFS both suggest that the strongest 10mb winds are yet to occur in the meantime (courtesy weatheriscool.com)

4 hours ago, s4lancia said:

Wrong thread I know but if this verifies, there will be reprocussions, big ones, for the currently dominate vortex. 

That shows 900m height at 10mb - only a little over the MERRA January average of 806 metres - which bear in mind includes predominately wave 1 phases when wave 2 dwindles.

Put another way, there are four out of 30 SSW (first of season) since 1979 where wave 2 is the overwhelming contributor in the fortnight before and up to wind reversal, to the exclusion of wave 1 - 22/02/79, 01/01/85, 21/02/89 and 24/01/09, leading to classic split vortices. All these had wave heights over 2000 metres. When looking at wave 1 + 2 jointly, the only SSWs occurring with as low a combined height total are a few at the end of March when the vortex is giving up the ghost.

Of course it's something to watch, but not amazing at this point. January days with wave 2 height between 850-950 metres have average 10mb 60°N wind 36.3m/s with an average minimum within 7 days of 27.4m/s. Only 1995 saw a weak reversal inside a week, but zonal wind was weak already, starting around 14 m/s.

4 hours ago, snowking said:

The only thing that I am rather wary of is the disconnect there seems to have been so far between the upper strat and the tropospheric vortex, but you would hope that given the huge downwelling downtick in zonal winds forecast there should be at least some impact towards the end of the month in our humble layer of the atmosphere

What is this disconnect that has been mentioned quite frequently?

For several weeks the troposphere and stratosphere vortices have been well coupled with barotropic structure - output from the models has shown that every nuance in the trop is affecting the pattern of the strat and anomalies. An alternative view is this graph of AO (scaled *5) vs 10mb zonal wind during December

The unlagged correlation is a highly significant 0.90

[bluearmy]

16 minutes ago, Interitus said:

Two CFS perturbations go for an SSW in February, using the reversal of wind as central date as is the general custom, the other perturbation and control show no SSW into March. The CFS and GFS both suggest that the strongest 10mb winds are yet to occur in the meantime (courtesy weatheriscool.com)

That shows 900m height at 10mb - only a little over the MERRA January average of 806 metres - which bear in mind includes predominately wave 1 phases when wave 2 dwindles.

Put another way, there are four out of 30 SSW (first of season) since 1979 where wave 2 is the overwhelming contributor in the fortnight before and up to wind reversal, to the exclusion of wave 1 - 22/02/79, 01/01/85, 21/02/89 and 24/01/09, leading to classic split vortices. All these had wave heights over 2000 metres. When looking at wave 1 + 2 jointly, the only SSWs occurring with as low a combined height total are a few at the end of March when the vortex is giving up the ghost.

Of course it's something to watch, but not amazing at this point. January days with wave 2 height between 850-950 metres have average 10mb 60°N wind 36.3m/s with an average minimum within 7 days of 27.4m/s. Only 1995 saw a weak reversal inside a week, but zonal wind was weak already, starting around 14 m/s.

What is this disconnect that has been mentioned quite frequently?

For several weeks the troposphere and stratosphere vortices have been well coupled with barotropic structure - output from the models has shown that every nuance in the trop is affecting the pattern of the strat and anomalies. An alternative view is this graph of AO (scaled *5) vs 10mb zonal wind during December

The unlagged correlation is a highly significant 0.90

in your opinion, which is taking the lead ?

from the sentence in bold, it seems you feel the trop is leading the way with wave breaking up into the strat. Assume you also mean the strat will dictate what occurs a little later in the trop without any influences from the trop pattern to alter things higher up??

Perhaps this should be in the strat thread - apologies

[Frosty.]

The Gfs 6z is eventually quite pleasing for coldies, especially from later next week onwards when the second stronger cold outbreak arrives from the NW..I'm desperate to see a snowflake as we are now into the fifth week of winter and at least there is some wintry weather showing on the models at times next week, especially for the north, occasionally cold enough for snow, and not just on hills and night frosts with an increasing risk of frosty, foggy settled weather during week 2.

[Purga]

I guess I keep beating the same drum... but ENS showing consistency again GEFS06z

It's worth a gander at the T2M as well (for London) as it's showing temps averaging not much above the 0C line as we move on.

Only a few members briefly breach the 10C line

The Control run was none too shabby in the later stages

I know it's easy to be cynical and understandable in this good Island of ours but as the saying goes there's still 'all to play for'.

PS: METO further update today still retains the chance of a v cold blast from the East later in the month albeit a very small chance.

 

 

Edited January 4, 2017 by Purga

[booferking]

8 minutes ago, Frosty. said:

The Gfs 6z is eventually quite pleasing for coldies, especially from later next week onwards when the second stronger cold outbreak arrives from the NW..I'm desperate to see a snowflake as we are now into the fifth week of winter and at least there is some wintry weather showing on the models at times next week, especially for the north, occasionally cold enough for snow, and not just on hills and night frosts with an increasing risk of frosty, foggy settled weather during week 2.

I hope it does deliver snow to low lying areas as all of the below so far this winter delivered one snow shower and that was back in Nov the rest we got nothing but rain and we usually do okay in North west in these type of setups.

[Scandinavian High.]

Yes all to play for maybe a easterly  low risk at the mo but signal is there.

[Rocheydub]

Nothing to see in the MJO at the moment. Think I'll take a break from model watching for a while, see can mother nature muster up more interesting charts.

[A Frayed Knot]

Yesterday afternoon i sent Judah Cohen a Email asking if the UK would get any colder or will we have any Snow ' I thought give it a go as he might reply ' and behold he did and this is his reply to me .

 

[Scandinavian High.]

This has been very consistent some sort of cold plunge later part of January maybe easterly flow or something from the north west.

[Summer Sun]

 

[The Giant Daddy Jackpot]

As we move into mid-winter cold and snow lovers are persistently frustrated by an Azores HIGH which re-emerges time and again sometimes slipping across the British Isles and keeping the Polar and Russian cold air teasingly close by to our North and East. This has been a similar set up for many years now with rare incursions to the North of Britain but never lasting long enough to take hold. Unless we see long-term ridging heights over Scandinavia and to our West in the Atlantic little will change. Even the NAO seems to have made little difference when one studies the cycle and the resulting winters across Britain. Ensemble data doesn't give much hope either in the short-term and suffice it to say, if we enter February with a solid Azores HIGH then its game over for yet another winter for real snow and cold lovers. Sorry!