Model output discussion - Jan 3rd onwards

[TSNWK]

9 minutes ago, Severe Siberian icy blast said:

Compare 12z with the 12z and 0z with the 0z, 

It's a huge improvement, we've got wedges of high pressure, a tanking neg ao, and no vortex over this side of the hemisphere, I think by tomorrow morning it'l look much better and this evenings will be an improvement again 

Absolutely with GFS and it's 4 daily runs and output in 6 hour slots whereby run to run comparison is not wise. However I do think with ECM and UkM we can run to run compare with them only coming out twice a day and in 24 hour increments..

[bluearmy]

An illustration of what happens when the ssw bomb goes off 

Now compact tpv                    V                        at day  10 very much not compact tpv

where the pieces end up is never solidly kown and therefore how it affects nw Europe 
 

       

[Nick_Somerset]

Just read the Sky News weather article...

UK weather: Could another 'Beast from the East' be on the way?

NEWS.SKY.COM

---

About 6-30 miles above the North Pole, there is an event occurring where temperatures may increase by up to 50C over a few days.

 ...pointing out the SSW Double Vortex, which is currently predicted. They state that this is the most dangerous kind of SSW breakdown...do we agree with that? 

[TSNWK]

15 minutes ago, bluearmy said:

An illustration of what happens when the ssw bomb goes off 

Now compact tpv                    V                        at day  10 very much not compact tpv

where the pieces end up is never solidly kown and therefore how it affects nw Europe 
 

       

Thank you. Great illustration. 

[ItNeverSnowsInWindsor]

Uncle Bartlett’s back thanks to the SSW!

 

[Drifter]

3 minutes ago, TSNWK said:

Thank you. Great illustration. 

But then GFS has this

[TSNWK]

4 minutes ago, Drifter said:

But then GFS has this

I guess that further supports the uncertainty.. will the SSW toss the vortex all over the place, will it relax and allow the Pv to  regroup as above.. 

my only crumb of comfort personally dispite the pretty dire output since new year for our part of the world is that every SSW by its very nature is unpredictable on how it effects the vortex in detail  and we have to place hope that chaos therory will support us on improved output soon

[IDO]

The transitional phase always trending to be not great for the UK, the development of the Arctic high and where the tPV pieces channel to have always looked to mean we are outside the colder options.

Post-d10 we will be hopefully heading to the next phase, as the westward momentum slows, assuming atm that the coupling overrides any trop background noises, where will the heights build?

d16 gefs suggest that by the last third of Jan the mean is indicative of the initial phase lasting, so trough Europe, US and Asia:

 London>

That is not a great long term pattern for the UK? No sign this initial pattern will support a BFTE.

Looking at the gefs, and the tPV although in pieces, there is no sign yet that it is crushed so we will probably need sustained strat forcing past d16 to prevent it from recovering? The signs are consistent but hopefully things will change so the UK gets some of the colder options rather than scraps?

 

[Chesil View]

We are looking at  most probably the final third of Jan before we see any fall out from the ssw be it favourable or unfavourable so it is pointless and futile agonising over op runs or even ens on January 6th.

In my opinion it will be at least another 7 days before we have any even semi reliable trop modelling regarding any possible strat induced effects of the SSW. 

Edited January 6, 2021 by Broadmayne blizzard

[bluearmy]

26 minutes ago, Drifter said:

But then GFS has this

Gfs doesn’t have the number of layers in the strat that ec does so theoretically won’t be as good at modelling an uncertain evolution. And that chart is at day 16 rather than day 10 

the para at day 16 for comparison (which has more layers higher up)

 

[carinthian]

Morning all . Have an update from the experts over here. Latest thoughts  throw a bit of a conundrum as early as 144t. For example the charts from UKMO/GFS  indicate less eastbound energy  than the current ECM , so retention of the high influence close to the British Isles remains. Going forward in the period 6-10 day period, the team are interested in the eventual pressure pattern to evolve between Western Europe and Iceland/ Greenland. Still some expectancy of height rises to the NW of Britain in their view and they still think the development of a Scandinavian trough is likely to produce their coldest spell of the winter season so far. How about the UK prospects I ask ? Certainly on a knife edge 50/50. Possible that SE England can stay cold in to early next week. So the crux looking ahead is to watch how the energy field pans out NW of the British Isles back to the Arctic region. So I have a feeling that all still to play for.

Good luck , from  deep snow covered Austria !

[Stu_London]

Looks essentially like the effects of the SSW will in the first instance initiate pattern change and a more westerly regime than we have seen for some time for a short period. This will end our rather anemic cold spell we have had since just after Christmas.

Does look thereafter that the cold pools will be much better aligned than of late. The models (particularly the GFS) will overstate the westerly regime for a while. Looking for a proper cold spell from the SSW, I would be looking for a few ensembles to start diving (kind of -12C 850s to -15C 850s or maybe even colder) in the next couple of days.

One of these may even manifest itself as operational run which will cause uproar in here, particularly as it will likely be gone on the next run.

For the pattern to gain traction, further ensembles will pick up on cold themes and we may well see the operational with its higher definition start to lead the way from about D11-D12. By this time the ECM and other models that go to 240 will be starting to cotton on as well. 

Cross-model and ensemble agreement should be pretty solid by D6-D7 (using Feb 2018 as a benchmark), but there will, as ever, be minor adjustments in the run up to the start.

As ever, a maritime climate with a warm ocean to our west, still has plenty of bust options - so no guarantees. 

 

 

 

[Stu_London]

To add: 

We may well see a phantom cold spell appear and then vanish again only for the same theme to be picked up again later.

I think that also happened in 2018 - where it was initially showed incoming cold around the 3rd week of February, whereas cold conditions only really came to our shores in the last 2-3 days of the month.

 

 

[Purga]

27 minutes ago, carinthian said:

Morning all . Have an update from the experts over here. Latest thoughts  throw a bit of a conundrum as early as 144t. For example the charts from UKMO/GFS  indicate less eastbound energy  than the current ECM , so retention of the high influence close to the British Isles remains. Going forward in the period 6-10 day period, the team are interested in the eventual pressure pattern to evolve between Western Europe and Iceland/ Greenland. Still some expectancy of height rises to the NW of Britain in their view and they still think the development of a Scandinavian trough is likely to produce their coldest spell of the winter season so far. How about the UK prospects I ask ? Certainly on a knife edge 50/50. Possible that SE England can stay cold in to early next week. So the crux looking ahead is to watch how the energy field pans out NW of the British Isles back to the Arctic region. So I have a feeling that all still to play for.

Good luck , from  deep snow covered Austria !

"from  deep snow covered Austria !"

You can go off people you know !..... seriously, thanks for your helpful input and hope you enjoy your snow,

[sebastiaan1973]

The Dutch plume ain't that great. So lot's of work to do.

[Battleground Snow]

Icon appears to have got stuck this morning, but it did just get far enough to show the snow still showing for Friday morning at a reasonable intensity.

Attached GFS for the same time period

 

 

[sebastiaan1973]

February and march EC seasonal. They are quite good. 

Quote

ECMWF | Charts

APPS.ECMWF.INT

 

 

[Battleground Snow]

2 minutes ago, sebastiaan1973 said:

February and march EC seasonal. They are quite good. 

 

Not bad... March is the main winter month in recent years, hopefully can also get the last week of January frigid too

[TSNWK]

I shall not tarnish this thread with any charts from the 06z. 
 

below is from parallel slightly more appealing.. just.

[northwestsnow]

8 minutes ago, sebastiaan1973 said:

February and march EC seasonal. They are quite good. 

 

Feb looks amazing..

Thanks for these Sebastian.

From SSW ?

Edited January 6, 2021 by northwestsnow

[northwestsnow]

4 minutes ago, TSNWK said:

I shall not tarnish this thread with any charts from the 06z. 
 

below is from parallel slightly more appealing.. just.

I've pretty much accepted things will flatten out for a while...

I'm not convinced it will be flat for more than 10 -14 days...

Edited January 6, 2021 by northwestsnow

[johnholmes]

My take on the next two weeks!

Wednesday 6 Jan looking at the 500 mb outputs

First looking at the ecmwf plots from 12-16 Jan and they show the upper ridge moving east pushing the trough, previously over the uk, well into the continent, both 500 and 850 mb heights rise along with 850 mb temperatures, the flow is westerly at 500 turning sw’ly over the uk.

Turning to the ec-gfs and we can see a similar pattern developing as the ridge builds into the uk with a broadly westerly flow coming out of n America. Upwind of this and the two are rather different, ec has no ridge down the west coast and the trough looks further west whilst gfs keeps the ridge. In my view ec is showing a better grasp of the 6-01 and further ahead pattern.

Looking at Noaa and the far west of the chart and it keeps the marked trough-ridge idea it has shown for the past 3-4 days, so not like ec. Further east and it is less meridional than several days ago but still not a flat westerly over the atlantic into the uk.

So we have, in the 6-10 day period, 2 for one option and one for another (Noaa). To me when this happens, and with gleaning some ideas from well beyond 6-10 days then I am not totally sold on the Noaa output, so its fence sitting time for a few days!

The 8-14 Noaa shows a similar pattern to the 6-10, and it is consistent with this for some days. However in view of events further out, predicted or otherwise I am yet to be convinced. In any case the contour line just south of the uk at 558 DM is quite a high value for early January so deep cold seems highly unlikely to me anytime in the next 2 weeks possibly longer.

Of course I may be totally wrong, time will tell but I can only give what I think is the most probable weather outlook.

ECMWF/GFS DAY 8-10 MEAN 500MB HEIGHT COMPARISON

WWW.METEO.PSU.EDU

Climate Prediction Center - 6-10 Day 500mb Outlook

WWW.CPC.NCEP.NOAA.GOV

 

[frosty ground]

2 minutes ago, johnholmes said:

My take on the next two weeks!

Wednesday 6 Jan looking at the 500 mb outputs

First looking at the ecmwf plots from 12-16 Jan and they show the upper ridge moving east pushing the trough, previously over the uk, well into the continent, both 500 and 850 mb heights rise along with 850 mb temperatures, the flow is westerly at 500 turning sw’ly over the uk.

Turning to the ec-gfs and we can see a similar pattern developing as the ridge builds into the uk with a broadly westerly flow coming out of n America. Upwind of this and the two are rather different, ec has no ridge down the west coast and the trough looks further west whilst gfs keeps the ridge. In my view ec is showing a better grasp of the 6-01 and further ahead pattern.

Looking at Noaa and the far west of the chart and it keeps the marked trough-ridge idea it has shown for the past 3-4 days, so not like ec. Further east and it is less meridional than several days ago but still not a flat westerly over the atlantic into the uk.

So we have, in the 6-10 day period, 2 for one option and one for another (Noaa). To me when this happens, and with gleaning some ideas from well beyond 6-10 days then I am not totally sold on the Noaa output, so its fence sitting time for a few days!

The 8-14 Noaa shows a similar pattern to the 6-10, and it is consistent with this for some days. However in view of events further out, predicted or otherwise I am yet to be convinced. In any case the contour line just south of the uk at 558 DM is quite a high value for early January so deep cold seems highly unlikely to me anytime in the next 2 weeks possibly longer.

Of course I may be totally wrong, time will tell but I can only give what I think is the most probable weather outlook.

ECMWF/GFS DAY 8-10 MEAN 500MB HEIGHT COMPARISON

WWW.METEO.PSU.EDU

Climate Prediction Center - 6-10 Day 500mb Outlook

WWW.CPC.NCEP.NOAA.GOV

 

What do you class as Deep cold?

[Ali1977]

Day 10 and things starting to look more interesting with the jet meandering , I have a feeling we are getting close to some great charts as the SSW comes into effect - definitely don’t be too downbeat just yet.

Edited January 6, 2021 by Ali1977

[sebastiaan1973]

10 minutes ago, northwestsnow said:

Feb looks amazing..

Thanks for these Sebastian.

From SSW ?

Well I suppose. It's contrary to the late winter La Nina setting.