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

[sawan]

1 hour ago, knocker said:

The ecm has a 160Kt jet swinging SE over Ireland at T126 introducing troughs running SE with bands of rain and  strong NW winds The latter very much the order of the day for the rest of the run as the HP mid Atlantic once more nudges NE Temps around average becoming a little below.

Knocker, this suggests that what models are showing is the garden path and false hope in la la land yet again? Or is there a chance beyond this active period after t126?

[radiohead]

12Z JMA at T192

[knocker]

7 minutes ago, sawan said:

Knocker, this suggests that what models are showing is the garden path and false hope in la la land yet again? Or is there a chance beyond this active period after t126?

It's really, at this stage  just the transition to an unsettled Pm incursion. Nothing should be read into it regarding future developments except perhaps what has already been suggested. Maybe a little more in a while.

[radiohead]

12Z ECM ENS mean is colder than the Op on Day 10

[Daniel*]

Well a cold Pm flow looks nailed on for at least 24-48 hrs.

Wintry precipitation not just for northern hills, I don't expect to see any watering down in 850 temps a lot of cold air to the northwest primed. Not a bad snow signal even for London, half the suite on the 12th strongest snow risk of the winter so far, maybe a wee lamppost watch for us down sarfff. 

[on the coast]

5 minutes ago, knocker said:

It's really, at this stage  just the transition to an unsettled Pm incursion. Nothing should be read into it regarding future developments except perhaps what has already been suggested. Maybe a little more in a while.

Will be interesting to see how week 3 looks like in the next coming days and if there is any kind of agreement from the main models. This may be the turning point of our poor winter for cold. 

[Connor Bailey Degnan]

Quite like the look of the ecm mean tonight, proper PM flow.  Snow would be a struggle to south eastern parts, but theres no reason why we can't change that flow to a northerly eventually

Hopeful thinking 

[Man With Beard]

That Canadian High ... might have support on the ens

[SMU]

Evening All

The ECM @ 144 is the first model that actually has a split flow over the UK with those low heights from europe all the back to De bilt 

just remember how far we have come!!

ECM 192 for the same time frame x2 days before 

& The GFS 192 x2 days ago

 

So im really pleased after the forecast how things have progressed -

I think we do have a bit more room for manouvre west, however we are beginning to cap out on that correction, it would seem that behind the deflected low @ 144 we have lost a bit of amplification & the atlantic does push forward again- all be it on a SE trajectory-

Overall the pattern ( post 144 ) screams chilly zonality with possible deeper cold in the mix down the line -But dont rule out further developments like above in the 120-168 arena-

Also eyes on the strat for week 3 / week 4 Jan as developments are just starting to take shape !

S

 

 

 

 

Edited January 4, 2017 by Steve Murr

[feb1991blizzard]

1 minute ago, Steve Murr said:

 

Also eyes on the strat for week 3 / week 4 Jan as developments are just starting to take shape !

S

 

 

Just wondering what timeframe are strat events progged for, when should we expect / hope to start seeing them come in range of the GFS?

[Nick F]

Not a particularly inspiring EPS mean in the 11-15 day range with the anomalies suggesting a continuation of the 500mb pattern in the 8-10 day of the deterministic with a NWly or Wly flow

However, the NOAA CPC 8-14 day indicates support for the 12z GFS, with a flow more N/NE than NW with perhaps the Euro trough eventually cutting off from the upper westerlies.

So, some divergence past day 8 GFS v ECM, so be interesting next few runs to see where we are headed. Now I'm ultra cautious since the New Year's Eve fail, I would go for the  ECM as the form horse, but with the NOAA 8-14 day amomalies siding more with GFS, not so sure.

[damianslaw]

Quite a bit of consistency between ECM,GFS and UKMO this evening and not just within the 96hr timeframe, but within the 120-144hr timeframe. All show a more amplified flow, with ridging building north through the mid atlantic, allowing for deeper troughing features. They all show an evolution to a north westerly blast in a weeks time, the potency and longevity differing between ECM and GFS, notably GFS is showing ridge development behind a diving trough, ECM looks like a renewed NW blast would occur following the first one.

 

[bluearmy]

22 minutes ago, Steve Murr said:

Evening All

The ECM @ 144 is the first model that actually has a split flow over the UK with those low heights from europe all the back to De bilt 

just remember how far we have come!!

ECM 192 for the same time frame x2 days before 

& The GFS 192 x2 days ago

 

So im really pleased after the forecast how things have progressed -

I think we do have a bit more room for manouvre west, however we are beginning to cap out on that correction, it would seem that behind the deflected low @ 144 we have lost a bit of amplification & the atlantic does push forward again- all be it on a SE trajectory-

Overall the pattern ( post 144 ) screams chilly zonality with possible deeper cold in the mix down the line -But dont rule out further developments like above in the 120-168 arena-

Also eyes on the strat for week 3 / week 4 Jan as developments are just starting to take shape !

S

Did you notice the spreads on th ECM steve - maybe a litttle surprise on the next op run? 

 

[SMU]

21 minutes ago, feb1991blizzard said:

Just wondering what timeframe are strat events progged for, when should we expect / hope to start seeing them come in range of the GFS?

Should be at the back end of the ENS from now-

I noticed a significant drop off in the 1HPA zonal winds today on the berlin page ( forecast )

CFS has however dropped the idea today-

I would still play it by ear..

 

cheers BA -  encouraging!!

 

 

Edited January 4, 2017 by Steve Murr

[knocker]

No surprise that the anomalies this evening continue in good agreement in the ten day range.

Still with the HP western Alaska with an active Canadian vortex (and a Siberian lobe) with the trough with a positive tilt SW. Still the ongoing connection via Greenland to the trough with a negative tilt orientated SE over Europe. Thus a continuation of a flat upper flow across the United states with a strong jet still leaving the eastern seaboard. This jet will track around the Azores high pressure which has the stronger positive anomalies in slight retrogression mode along with the ridging north. All three are in pretty fair agreement on the relative portions of the HP and the alignment of the aforementioned trough to the east so pretty high confidence in a period on unsettled wintry weather in the Pm incursions from the NW with temps below average. The det. runs will of course sort out the detail

In the 10-15 time frame the expected retrogression of the Alaskan HP still in play with broad low pressure area in the N Pacific but the Canadian vortex still a player. But there is no agreement on the vortex - trough to the east connection with the GEFS playing it down and encouraging some more mid Atlantic ridging and thus still a NW flow to the trough to the east which has got a negative orientation to the SE. The ecm is not liking this and generally moves to a zonal upper flow with a very weak trough to the east. Which ever way you hang this it is difficult to see any other solution than a general W/NW upper flow and with the strong jet a continuation of periodic incursions of Wintry PM fayre and temps below average

[bluearmy]

Nick F, the CPC charts never include 12z ECM data so not surprised they look better than the most recent eps suite which, as you say loses some of the Euro low anomoly intensity post day 12 whilst increasing the cold in the 8/12 in the mean nw flow. (Which would probably fluctuate nw/N/ne)

the geps also losing the cross model consistency post day 12 with the Euro low anomoly so we need to keep an eye on where the ens are going end week 2. no sign yet on the return of the euro high anomolies but where nothing is now shown, those higher ones could drift in. 

[snowbob]

6 minutes ago, Steve Murr said:

Should be at the back end of the ENS from now-

I noticed a significant drop off in the 1HPA zonal winds today on the berlin page ( forecast )

CFS has however dropped the idea today-

I would still play it by ear..

 

cheers BA -  encouraging!!

 

 

Quick question Steve 

with the strat events, was led to believe there was a considerate amount of down dwelling before we saw any signs in the models.

also that the cfs was cannon fodder for such events. Chalk and cheese for atmosphere modelling.

just trying to get a handle

 

 

 

[Summer Sun]

GFS para is back

The 06z shows the coldest spell around Friday 13th to Sunday 15th

Beyond this, some chiller air makes inroads but nothing of any great significance

[shotski]

8 minutes ago, knocker said:

No surprise that the anomalies this evening continue in good agreement in the ten day range.

 

Great news Knocker, looks like a continuation of a cold outlook. 

Edited January 4, 2017 by shotski

[Zakos]

The Siberian High looks set to become very large according to the ECM and GFS means. Could this weaken the PV? or perhaps aid our pattern by pushing it further west, and perhaps deepening low heights over Europe?

In the shorter term - 

Personally very encouraged by the ECM mean 144. looks like how heights are becoming entrenched over europe. Won't this, coupled with lower temperatures in the region, help to potentially force the jet stream  to take a more southerly track?

No raging Greenland High, but a darn sight better than what we had this time last month

All to play for IMO

 

 

[Nick F]

1 minute ago, bluearmy said:

Nick F, the CPC charts never include 12z ECM data so not surprised they look better than the most recent eps suite which, as you say loses some of the Euro low anomoly intensity post day 12 whilst increasing the cold in the 8/12 in the mean nw flow. (Which would probably fluctuate nw/N/ne)

the geps also losing the cross model consistency post day 12 with the Euro low anomoly so we need to keep an eye on where the ens are going end week 2. no sign yet on the return of the euro high anomolies but where nothing is now shown, those higher ones could drift in. 

Cheers, thought as much, I suppose the EPS mean will hide possible shifts in the flow to N and NE like you mention, though does highlight the low chance of height rises to the north and northeast which are represented in the 12z GFS op and GEFS mean post day 10.

[tight isobar]

Now that's what im getting at!!!

Azores hp and siberien/Russian' playing ball for decent cold...and perhaps a locked in phase.....

[SMU]

28 minutes ago, snowbob said:

Quick question Steve 

with the strat events, was led to believe there was a considerate amount of down dwelling before we saw any signs in the models.

also that the cfs was cannon fodder for such events. Chalk and cheese for atmosphere modelling.

just trying to get a handle

 

 

 

A rough guide is 10-14 days - thats from the moment the zonal wind starts its massive deceleration to the moment it goes negative ( Easterly )

S

eyes down for the 18z

[feb1991blizzard]

1 minute ago, Steve Murr said:

A rough guide is 10-14 days - thats from the moment the zonal wind starts its massive deceleration to the moment it goes negative ( Easterly )

S

eyes down for the 18z

The deceleration at 1mb looks a steep downturn, but usually to sustain and progress deceleration and then propagate down through the levels, there would surely be a very strong warming now showing at the top.

[Glenn Redwood]

That will be good Steve?  You said patience would be needed.  To me the charts seem to be gathering pace for more cold shots mid-month.