Model Output Discussion - Into the new year

[That ECM]

Loving the ECM if we can get to this then look at the advancing cold from the East. All JFF at this stage.

[KTtom]

12 minutes ago, West is Best said:

There might come an easterly out of this but words about 'solid agreement for a perfect alignment' make me nervous. The progression of the high pressure cell towards Iceland is a precarious synoptic setup at the best of times. A small shift and we find ourselves under a high pressure not an easterly and many, many, many times easterlies have been promised even at short notice only to come to nothing (John Kettley's infamous beast from the east being the classic example).

The models have generally trended more cold over the past 24 hours but only by a notch. My concern is that there remains a lack of 1. robust upstream blocking and 2. significant cold pooling to our east, although this has improved slightly. It should also be noted that later on in the run  0z GFS has a south-easterly veering southerly: in fact what Steve Murr used to call the backdoor exit from a cold spell. This is because it has the hp evaporating. That also needs to be watched as it's a relatively new development with the GFS which has continued to be all over the place past T168 - another reason to be cautious. In addition we should note that in FI models are continuing to show Atlantic low pressure cells and without robust upstream blocking this should be a cause for concern. It can, of course, be the prelude to proper snow: when a low pressure collides with cold pooling and the undercut leads to real snow. We are a long way from that scenario at the moment. The 0z ECM indeed has the hp cell eventually moving so far north that the cold uppers over the UK lift from the south: we lose the cold source. 

These setups are precarious. I can only really remember one perfect alignment for an easterly and that was February 1986 - one of the three coldest months of the C20th I believe but one hardly anyone remembers as it was simply cold. No snow. Just bone chilling boring dry cold.

At the moment I see evidence to stick with the Met Office that we're in for a week of cold weather, with rain, sleet and snow but also a lot of dry weather. Temps below average but nothing seismic or significant. Pretty much in line with the kind of below average conditions we experienced in July and October. Beyond T144 at the moment is unclear and uncertain. Caution should be the watchword not over-enthusiasm. At least for now.

Totally agree, the word 'perfect' was in relation to the position of the high, not the easterly, which may be in the form of a north easterly (colder as per ECM), or a south easterly as per gfs which sources its air from the Med and is therefore less cold. Certainly no real hint of a memorable easterly, hence I guess that's why those who get paid a lot of money to do the forecasting make a point in saying so (I think that sentence is put into the forecast in anticipation of the press headlines!  

ECM day 10 probably the best chart out there this morning, especially in terms of some very cold air finally showing signs of dropping down into Scandinavia, maybe a regress to the north west if it went out further? should it occur it may benefit the UK further down the line. 

Edited December 28, 2020 by KTtom

[Kentspur]

Is that almost a Steve Murr type sausage high developing at 240 on ECM, minus 7c uppers back in over Kent with widespread minus 6c everywhere south of the Midlands and wind direction remains Easterly 

Edited December 28, 2020 by Kentspur

[northwestsnow]

Look away now Greek cold weather fans!!

About time too.

The Greeks have had a good run during recent winters,courtesy of the  Euro high.

Sorry boys, no Euro high for a while.

 

[tight isobar]

Real pivot on now (as the track-east/south east is on)-and we see back banding.. almost another system in creation over mid wales.. shouts intensification.. interesting this morning.. 

[Griff]

3 minutes ago, tight isobar said:

Real pivot on now (as the track-east/south east is on)-and we see back banding.. almost another system in creation over mid wales.. shouts intensification.. interesting this morning.. 

Yes keeping a close eye, I suspect East of the main central band will require watching... out the window. 

Edit: would give some support to the currently fantastical BBC forecast of snow showers this morning IMBY, which is way out on its own. 

Edited December 28, 2020 by Griff

[snowangel32]

14 minutes ago, tight isobar said:

Real pivot on now (as the track-east/south east is on)-and we see back banding.. almost another system in creation over mid wales.. shouts intensification.. interesting this morning.. 

Yep its given a decent amount about 4cm here so far also thunder snow in places. Strangely icon did the best with this little event. Still snowing here as the pivot starts to push bk west.

[Polar Maritime]

Yes let's keep all the non model/real time radar snow watching to the cold discussion thread or regionals as to keep this thread on topic. Thanks all

[IanT]

18 minutes ago, Griff said:

Yes keeping a close eye, I suspect East of the main central band will require watching... out the window. 

Edit: would give some support to the currently fantastical BBC forecast of snow showers this morning IMBY, which is way out on its own. 

Cooler here (Woking) than generally modelled. Showing -1.5c vs +2c. Heavy frost. A few flakes mid-morning may just be possible...

 

Well I did mention modelling 

Edited December 28, 2020 by IanT

[That ECM]

T240 gfs mean. There is some crackers in the 30 perbs.

[Polar Maritime]

No more please as above here's the cold spell thread-

 

 

[mulzy]

An early look at the extended EPS mean shows good continuity from last night's run with subtle (even better) changes.  The low heights anomaly pushed a little further east into Central Europe with heights over Scandinavia and eastern Europe dropping away more strongly compared to last night's run.  The low heights anomaly then extends back to the Azores meaning that the negative NAO risk is still there (clusters will reveal more). The ridiculously high heights anomaly remains around North East Canada/Western Greenland.

I would say the EPS are a very good match to the GEFS in the extended timeline.

I know this has been said a few times before but this has to the best set of extended EPS this winter season.

Edited December 28, 2020 by mulzy

[northwestsnow]

EC mean is cold.

Subtle hint of HP pulling west   need those arctic floodgates to open...

[Frosty.]

We’re not in Kansas anymore!..loving these ECM 0z op charts...sooo much better / nicer than the usual default mild mush..long may this continue..until April!!

Edited December 28, 2020 by Jon Snow

[sheikhy]

My god what a set of runs this morning!!850s upgrading much earlier at only 2 or 3 days out as well!!home grown cold maybe?oh and to add snow events popping up now at very short notice!

[Nick F]

Agree the lack of deep cold to the east to tap into when the models are showing long draw easterly is frustrating, so the classic snow shower generation over the North Sea when you get deep cold crossing the relatively warmer sea would be more of a struggle. So we'd have to rely on low pressure systems moving in from the west under the block to the north, or, troughs in the easterly flow circulating in low pressure on near continent, for snow chances, as the fronts bump into the surface cold flow.

If, from the likely SSW around 4-5th Jan, we get a split SPV, with a daughter vortex over NE Europe/NW Russia or displacement of the SPV to this area, then should the trop/strat couple together, this may provide the impetus to push the deep cold lurking over northern Russia to  shift west across NE Europe. Yesterday's EC update on Berlin and 00z GFS showing this: the vortex over NE Europe

Until then, plenty of interest for brief snow events across the UK from a plethora of troughs, secondary lows and fronts circulating around the 'parent' low parked over the North Sea this week.

Tuesday an occluded front moving SE from the North Sea down across N England, Mids and toward Wales and S England looks to bring some snow.

Wednesday, some uncertainty, but a low tracking SE over or near Ireland could swing more east in track across southern UK, like EC, 03z UKV further south, but with sleet/snow across southern counties. GFS and ICON take the low further south over N France - so missing the UK.

Thursday / NYE could see another front dropping south to bring some snow inland.

Plenty going on and there might be other disturbances this week not picked up on yet almost anywhere.

Edited December 28, 2020 by Nick F

[nick sussex]

Some very encouraging outputs this morning for coldies but the issue of what any easterly would produce is still up in the air .

Because there’s no injection of arctic air into the mix any cold pooling needs to be developed and this means the 850 values which we see to the east are likely to be unreliable this far out .

The best easterlies are ones where troughing drops south to the east and its associated cold pool then gets advected west . We don’t have that here.

The benchmark normally for a good easterly with convection is 850 values -10 or below.

A few -8 pop up , can we get there a couple of degrees colder . The ECM also shows a shallow feature moving west , the rules governing that are somewhat different .  

And given the timeline it might not appear on the next run.

Hard to grumble though as for the next ten days there are snow chances , detail wise though that’s still hard to nail down!

But certainly plenty to keep an eye on which should keep this thread busy!

Edited December 28, 2020 by nick sussex

[TSNWK]

2 minutes ago, nick sussex said:

Some very encouraging outputs this morning for coldies but the issue of what any easterly would produce is still up in the air .

Because there’s no injection of arctic air into the mix any cold pooling needs to be developed and this means the 850 values which we see to the east are likely to be unreliable this far out .

The best easterlies are ones where troughing drops south to the east and it’s associated cold pool then gets advected west . We don’t have that here.

The benchmark normally for a good easterly with convection is 850 values -10 or below .

A few -8 pop up , can we get there a couple of degrees colder . The ECM also shows a shallow feature moving west , the rules governing that are somewhat different .  

And given the timeline it might not appear on the next run.

Hard to grumble though as for the next ten days there are snow chances , detail wise though that’s still hard to nail down!

But certainly plenty to keep an eye on which should keep this thread busy !

Morning Nick.  Any updates on the crunchy snow and Ice day alert system please.. are we on standby yet?

[nick sussex]

8 minutes ago, TSNWK said:

Morning Nick.  Any updates on the crunchy snow and Ice day alert system please.. are we on standby yet?

The alert system is still waiting to be activated ! We don’t have the depth of cold yet. Still need to see what that easterly might produce but I’d rather take a glass half full approach . Given some of the mild crud that could have been served up I’m quite happy with today’s outputs and UK coldies are in the game as opposed to being 4-0 down at halftime ! 

Edited December 28, 2020 by nick sussex

[Tim Bland]

EXM snow depth by Friday! as nick says - lots of features fir different areas to watch over the next few days. Below is a result of 4 different areas of snow over the next few days ...

[Methuselah]

Great to see the deep cold take a positive lurch in our direction, during the latter stages of the GEFS NHP Profile progression:

    

    

And everyone loves a lurch: 

[Kent Clipper]

Another long day of model watching ahead. I really need to get out and distract myself with something else for a while. 

This weeks slack self generating cold pool continues to excite with a host of marginal possibilities providing all sorts of wintry opportunities. What isn't being spoke about too much is the likelihood of some very low minima and freezing fog. Always a nice measure of winter cold.

Last night a surprise hail shower thanks to this set up provided me with a nice covering of white at 1am.

The new year easterly is gaining momentum and this is great but we really do need a fresh injection of arctic air if we are going to set the North Sea Snow shower convection machine into operation, and by this I mean 850's of -9 or colder. We are not far off and only small downward adjustments will get us there. Next weeks eastern based wintry showers as things stand are not going to cut the mustard after this weeks marginal possibilities. Snow lovers will be demanding more ! 

Indeed next week could even become a little less cold due to the maritime mixing from the North Sea. (one to be aware of).

Further south we look to the NE for cold upper air generated snow showers but we are also looking towards the SW for an attack that could provide a significant snow event and in this set up 850's of -1c or less are required if we draw in a direct continental ESE'ly feed. The risk with this is less cold southerly air pushing in ( a la demise of the 2018 BFTE).

Lots of excitement and up to 168-192 all is good. ! 

Personally I would like to see this cold pool stagnate for a few days longer, get in a NE'ly, dig a trough into Scandi, retrogress the mid atlantic high to Iceland and let mother nature do the rest. Not too much to ask for is it ! 

Edited December 28, 2020 by Kent Clipper

[Anthony Burden]

Russia here we come,ECM GFS showing harmony easterlies all the way.Would not 

worry over 850hpa it will unquestionably be cold enough if these charts are correct.

As Nick F  stated surface cold will continue and SSW if goes are way could drag that

very cold air towards us.

[Tim Bland]

14 minutes ago, Anthony Burden said:

Russia here we come,ECM GFS showing harmony easterlies all the way.Would not 

worry over 850hpa it will unquestionably be cold enough if these charts are correct.

As Nick F  stated surface cold will continue and SSW if goes are way could drag that

very cold air towards us.

GFS isn’t showing easterlies all the way Not saying it’s correct but could be misleading to members staying to do a quick catch up. GFS is pants this morning in comparison to yesterday. Hope it flips back again in the 06z. I think the pattern over the last couple of days has been for a poor 00z then a reasonable 06z,  then a stonking 12z. 

[Penicuikblizzard]

2 hours ago, Kentspur said:

Is that almost a Steve Murr type sausage high developing at 240 on ECM, minus 7c uppers back in over Kent with widespread minus 6c everywhere south of the Midlands and wind direction remains Easterly 

The uppers through this period are up and down for a Easterly,,,it’s not backed up by real cold ie -20 uppers across the continent 

we seem to be sitting between -4 to -7 uppers at best over the UK