Model Output Discussion - The Start Of Winter

[bluearmy]

Just skipped over the gefs members at day 16 and to me, it seems they are trying to get a handle on where to go but making a bit of a pigs ear of it. Some mid Atlantic ridges, some Siberian ridges and a couple of members that would lead to a complete Pv breakdown and severe cold in the mid latitudes. of course, a few mid lat highs over nw Europe and displaced upper troughs. anyone got a pin?

[snowice]

Is the gfs12z to be bined because of the missing data so called red Run?

[nick sussex]

NCEP prefer solutions more amplified upstream. The GEFS 00hrs ensembles were ditched for being too flat aswell as the GFS 00hrs run, they preferred the ECM 00hrs ensemble mean aswell as the GEFS 06hrs because these trended to more amplitude, this is now supported by water vapour imagery from the Pacific.

 

This update won't include the latest ECM run however, we'll have to wait for some of the US state forecasts when they update later on.

[Recretos]

This past 18 hours ( leading on from my post last night ) shows that using the 10 day mean, the 16 day Mean & the CFS mean is pretty useless, the models are picking up on the jet dropping a LONg way south over the NE states which is encouraging heights further & further North ahead of it-

 

Note the negative tilted low at 114 in the states ( remember what was said yesterday)

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014120512/gfsna-0-114.png?12

 

 

Actually the main trough axis does appear more neutral/positive tilted, with the low core slightly ahead of the main trough axis. I would call it neutral/positive tilt. 

[SMU]

Sorry its going from positive to negative my meteociel chart was 24 hours ahead of the 114 chart I posted.

 

114 slightly pos

 

138 to negative

 

S

Edited December 5, 2014 by Steve Murr

[Gael_Force]

That's not the same T114 chart.

 

That's not the same T114 chart.

 

Both charts are the T114 from the 12Z  GFS - I used the Instant one as it was clearer regarding the isobars.

 

[IDO]

 

That's not the same T114 chart.

 

That's not the same T114 chart.

 

Both charts are the T114 from the 12Z  GFS - I used the Instant one as it was clearer regarding the isobars.

 

 

 

Its a positive tilt on the chart you showed though:  

[Mucka]

The cold Northwesterly of late Sunday/Monday just beginning to come into range for Euro4, looking good for some wet snow to fall to low levels in the North.

 

Edited December 5, 2014 by Mucka

[gottolovethisweather]

Meanwhile.................

 

Anyone left wondering how the reliable timeframe is being forecasted by the ECM 12z can view the attached. It does still look likely to a be notably deep depression even now. What surface conditions and general weather type will be delivered beyond its passing through or over the UK remains a most pertinent question right now. 

 

 

And at t+120 hours.

 

 

Here is UKMO version by way of comparison for the same timeframe.

 

Edited December 5, 2014 by gottolovethisweather

[BLAST FROM THE PAST]

 

Looking very nice folks  snow for lowland UK coming?  If upgrades  continue then not an outlandish thought

 

 

 

 

BFTP

Edited December 5, 2014 by BLAST FROM THE PAST

[Mucka]

JMA has the PV  and an Arctic high forming.

 

[terrier]

Sorry can't post charts as I'm at work but the deep low on models tonight look like bringing us a lot of rain and gales next week. Not great. Scotland should see a lot of snow though. So the gritters will be busy. While most of U.K. might need a boat.

[Barry12]

A change is definitely on the way, interesting times ahead

 

 

Nothing mild in the foreseeable...

[Polar Maritime]

A much better Northerly from the ECM, With the low digging further South.

 

Edited December 5, 2014 by Polar Maritime

[Dancerwithwings]

 

Looking very nice folks

 

BFTP

Big big differences from this time yesterday.... Looking good

 

[Snowman.]

Ignoring the GFS op as it looks an outlier. The GEFS mean for D16 continues the NH theme to displace the Canadian/Greenland PV lobe. More towards the Siberian region tonight:

 

gensnh-21-1-372.png

 

So as would be expected a cluster of more amplified members at that time scale. So the last third of December remains the most likely for a pattern change still.

 

Don't the GEFS members usually lag behind?

 

Like when we get led up the golden path then the OPs through two wild ones the GEFS continue to show the output of somewhere around a day behind?

 

 

But good trend none the less that maybe we can rid the lobe from greenland once and for all.

[Cloud 10]

Hugely positive temperature anomalies at day 7 over Canada on the 12z ECM,with H500 along side......

 

 

[Summer Sun]

Interesting run from GFS for next weekend

 

 

Temperatures really struggling these are the MAXES

 

 

 

[Eskimo]

 

 

[nick sussex]

I wonder how many ECM ensembles might show a ne/e flow for De Bilt after day 10.

 

Overall some more positive output in the medium term for coldies but theres still a lot of complex interactions that will take some time to resolve over the USA and Canada.

 

So I think we'll need a few more days to see how this effects the pattern over western Europe.

[Geordiesnow]

I'm more confident the Canadian Arctic PV will go now, there is huge agreement on that for certain, the question will be how much amplification will there be, the models do seem to be trending on a more amplified outlook towards Newfoundland but of course, any short term shortwaves could always scupper this before you know it. 

 

Regarding the deep low, it has been toned down to a certain extent but the models are still showing it will still be quite a deep low, just how far Eastwards it will head will depends how severe the impacts will be and how tightly packed the isobars will be.

 

Whilst the outlook might not be a full on cold lovers dream, its hardly a cold lovers nightmare either, far from it. How will the weather pattern change across Canada will affect us and will it affect the PV over Greenland. Many more twists and turns to come yet for sure and I advise not to look in too much detail of each run.

[OldMetMan]

What a difference a day makes!

The main models are offering up some very tasty possibilities to come next week. It's quite extraordinary how today all the energy that was shown to be following on from the major storm next week, has suddenly faded away.

The aforementioned storm now seems consolidated in the model output, so we are left with a variety of solutions as to what follows it. I mentioned yesterday how storms of this size and intensity can significantly alter the upper flow and this would appear to account for the model differences today.

So we have several possibilities here:

1. As per the 12Z GFS, NW turning N with the distinct possibility of polar lows/troughs forming as the cold air floods S

2. A briefer northerly, followed by a fast-moving shortwave running SE, in turn followed by a renewed burst of cold air.

3. A flatter pattern, as was shown yesterday, with further disturbances running W to E but no significant cold air breakthrough or 500mb amplification.

It's tempting to think that if the two major models, GFS and to a degree, the ECM are roughly in agreement, then that is what will happen. Still too far off to know with any certainty but if only from an historical perspective, in such situations, the cold air usually wins.

If the 500mb flow does weaken over E Canada and US as shown, then I would think cold is inevitable. Being this early in the winter, the sea warmth could create some fascinating situations as the cold air runs over it, with significant snowfall in some places.

Let's see how subsequent runs pick up this trend but right now, it sure looks hopeful.

[blizzard81]

 

 

The low sinks into southern Europe, the Azores high ridges up to meet the ever growing Siberian high and hey presto, easterly incoming at day 12. The tweet by Matt Hugo last night made reference to the EC cluster bringing in an easterly at 2 weeks out.

[Man With Beard]

A change is definitely on the way, interesting times ahead

 

 

Nothing mild in the foreseeable...

And GFS / ECM in reasonable enough agreement - that is encouraging. And I notice greens returning to the southern tip of Greenland at the same time.

I think we are getting close to the point where lowland areas are in the game for some snow too.

[BLAST FROM THE PAST]

Big big differences from this time yesterday.... Looking good

 

Indeed, so GFS, ECM, JMA, NAVGEM, UKMO all heading the right way for cold outbreak,  For me this is the first steps,

 

BFTP