Model output discussion - winter proper underway

[Nick F]

18z GFS op perhaps a reality check, given the 12z operational was at the colder end of its own ensemble spread and also against the EC ensembles for London

Still think we will see changes for the better as we approach New Year, but 06z and 12z GFS ops perhaps a tad too quick with the pattern change.

Edited December 13, 2017 by Nick F

[booferking]

2 minutes ago, Nick F said:

18z GFS op perhaps a reality check, given the 12z operational was at the colder end of its own ensemble spread and also against the EC ensembles for London

Still think we will see changes for the better as we approach New Year, but 06z and 12z GFS ops perhaps a tad too quick with the pattern change.

So best to keep money in pocket for no White Christmas.

[Guest]

I was expecting some volatile output and some quite unusual synoptics as models come to terms with the anticipated broader pattern change around Christmas to early January but this is absolutely bizarre. 

GEFS 18z Perturbation 5:

             From this at T+276                                       to this at T+324                                         and to this at T+384

                             

 

Nothing exceptional on the first chart. That LP on the middle chart has a central pressure below 915 mb - very close to an all time Atlantic record.  Nearby we have an HP over 1050 mb.  A couple of days later, under the strain they just break apart!!!  Even by GFS standards this takes the biscuit (to put it politely!).  More than just a pub run special - a flat out pre Christmas pub crawl.

Well, quite a few of us are expecting something memorable and whatever transpires full marks to the GFS for entertainment value!

EDIT: record low is 914 mb on 8.1.93  (and 882 mb for a hurricane in October 2005)

Edited December 14, 2017 by Guest
Correct typos and check charts

[CanadaAl]

True to GFS's unpredictable nature, after being a cold outlier for the 12Z, The 18Z appears a milder outlier in the 18Z ensembles. 

 

[Ali1977]

6 minutes ago, ShortWaveHell said:

00z Gfs Christmas Day miracle , a beast awakens 

Yep, great run and this will please many waking up on here today ...

[East_England_Stormchaser91]

What a difference 6 hours makes. Run of the decade this 00z!! 

Sorry to ramp, but to me, the right building blocks look well in place this year. Very different parameters compared to the last few years, low sunspots, no El Niño and an E QBO and a shabby PV certainly compared to the last few winters. 

[Ali1977]

Not a huge amount of ENS support but a few with interest and definitely some attempts at Scandy hights and split PVs. 

A live image of Wanlockhead just to get us in the mood, just to show that there's still plenty of snow still falling out there this week. 

[sparky71a]

25 minutes ago, Ali1977 said:

Not a huge amount of ENS support but a few with interest and definitely some attempts at Scandy hights and split PVs. 

A live image of Wanlockhead just to get us in the mood, just to show that there's still plenty of snow still falling out there this week. 

At 1460ft asl and 2nd highest village in Scotland it probably gets its fair share, I know what you mean though ?

[KTtom]

1 hour ago, Ali1977 said:

Yep, great run and this will please many waking up on here today ...

Dont think ive ever seen a northern hemisphere chart like this during the winter....?

Edited December 14, 2017 by KTtom

[chris55]

 Very cold GFS 00z operational in the mid term, U.K. sitting under a cold high Christmas Day with an easterly influence. Would be very seasonal.

Though a big outlier on the ensembles, GFS keeps doing this, with the op out of kilter.

Edited December 14, 2017 by chris55

[northwestsnow]

GFS looks great!! Scandy high building over christmas period!!

EC however.....

gfs again showing the strat warming over christmas

Edited December 14, 2017 by northwestsnow

[swfc]

Good looking oz from gfs.however the difference between ecm is massive and really odd imo.not even close to a middle ground at 240hrs!!!!!!

[Dennis]

1 minute ago, northwestsnow said:

GFS looks great!! Scandy high building over christmas period!!

EC however.....

EC is close to it..... 10 days to go

[northwestsnow]

EC day 10

Wonder if the picture would improve thereafter with the jet digging SE and the azores high getting dragged westwards..

Edited December 14, 2017 by northwestsnow

[snowbunting]

0z demonstrating to us that zonal mild atlantic just isnt going to happen for long periods of time. Significant change to colder synoptics expeced around Christmas if these last few runs of the gfs are to believed. 

[geordiekev]

1 hour ago, KTtom said:

Dont think ive ever seen a northern hemisphere chart like this during the winter....?

I want to believe 

[nick sussex]

Operation Save Christmas hangs on the GFS trend being correct!

The ECM hits the buffers early with a poor upstream pattern.

However NOAA have not sided with the ECM and have highlighted huge uncertainty .

More about that later after my coffee!

Edited December 14, 2017 by nick sussex

[bluearmy]

Ecm mean and anomoly finally showing what part of gfs ops has been on the right page and not surprisingly it’s a bit more amplification around day 8 to our west 

that makes the trough to our east that bit sharper which helps make e Europe colder (spread also has that colder air making a glancing blow to e side uk) 

Also takes our ridge that bit further north 

Edited December 14, 2017 by bluearmy

[northwestsnow]

2 minutes ago, bluearmy said:

Ecm mean and anomoly finally showing what part of gfs ops has been on the right page and not surprisingly it’s a bit more amplification around day 8 to our west 

that makes the trough to our east that bit sharper which helps make e Europe colder 

Also takes our ridge that bit further north 

Well thats a positive this morningblue

GFS (yes i know its gfs) 00z op showing quite a warming in the strat over christmas period..

EC looks flatter than ukmo 144 -

Edited December 14, 2017 by northwestsnow

[Severe Siberian icy blast]

57 minutes ago, northwestsnow said:

GFS looks great!! Scandy high building over christmas period!!

EC however.....

gfs again showing the strat warming over christmas

I'm sorry showing a warming repeatedly  at 384hrs is absolutely useless, we can't even get these to come in fruition within the 200 mark so what's the point? 

[northwestsnow]

Just now, Severe Siberian icy blast said:

I'm sorry showing a warming repeatedly  at 384hrs is absolutely useless, we can't even get these to come in fruition within the 200 mark so what's the point? 

I know

Although the warming at 10Pha does get going before 384

288

Hopefully the Berlin day 10 will be good news ..

[BLAST FROM THE PAST]

The whole month is looking colder than expected and indeed I see potential for Development of a major Scandinavia block as we head to New Year, much earlier than initially thought.  However, if it does I question what influence it will have

 

Above is an extract from my winter LRF update musings on 5th Dec.  I am definitely in the GFS camp here and think it is barking up the RIGHT tree.  00z turns it very mild at the end....hence my musings on its influence.  

ECM played catchup with last cold outbreak 

 

BFTP

Edited December 14, 2017 by BLAST FROM THE PAST

[joggs]

Didn't the Ecm struggle with the upstream pattern(too flat)before our previous cold spell?

[Chesil View]

Just now, joggs said:

Didn't the Ecm struggle with the upstream pattern(too flat)before our previous cold spell?

i think it did joggs i remember posts about how it was unusual to see the gfs going for more amplification than the usually over amplifying ecm

[nick sussex]

Just looking at some US state forecasts theres hope that the ECM isn't correct upstream.

New York state forecast:

Thereafter, the forecast is much more uncertain. Downstream
shortwave begins to make eastward progresses as ridge flattens. Weak
PVA noted in fast zonal flow approaching area Sunday night, which
could trigger some light precip. Then, operational ECMWF remains a
fast and stronger outlier as this mid west shortwave moves east.
This would result in higher precip chances Monday when compared to
GFS and Canadian NH.
 

Maine State forecast:

For now, have favored a solution similar
to the 13/12Z GEFS with a coastal low on Wednesday bringing
potentially significant snow. The 13/12Z operational ECMWF shows
a coastal low on Monday night, but this solution involves
kicking a Four Corners low out of the SW US too quickly and it
is not supported by the majority of ECMWF ensemble members.

There is though still the complication regarding whether shortwaves in the mid Atlantic phase with the upstream trough as happened on last nights GFS 18hrs run which stopped better WAA up to Greenland. This mornings GFS run avoided that at the key timeframe so even if its correct versus the ECM there are still hurdles to overcome.