Model Output Discussion - Spring Has Sprung

[IDO]

  @Dennis

I am not sure those datasets equate to a GH; well, not a blocking high. This is a GH, but not really much help:

The 12z suggests the tPV is losing momentum in FI. D15:

A bit wedgy. Maybe changes as we move towards mid-February?

[Chesil View]

All completely Just for fun at that extended range but the 12z gfs op wouldn't take that much tweaking to provide a UK snowfest.  I would imagine there might be an ensemble or two that do just that.

Edited January 26 by Chesil View

[northwestsnow]

Deep FI is absolutely incredible with a 2 day snow storm

[Metwatch]

From the 06z GFS, much weaker westerlies in the troposphere after next weekend!

No surprise when it showed this as the output:

Now the 12z. Most of the PV vacates North Canada / Greenland, and the jet dive-bombs into the Azores / Iberia. Note the Aleutian low as well.

Perhaps reacting to the +EAMT and rising AAM + MJO? i'd say it's possible, but a fair while to go...

Edited January 26 by Metwatch

[Tim Bland]

Let’s hope for the usual shift south

[damianslaw]

Interesting GFS output for early February, polar vortex stretching and moving east to scandi, thereafter heights still strong to the south, but there appears to be space for heights to rise to the NW, all long term range but it sets up a stage for low heights to sneak in from the SW scrubbing heights to the south. Not sure it has developments right timewise but may be the direction we head in by mid Feb.

In closer timescales UKMO now showing the stretch in the PV eastwards as well 168hr.. this appears to be the precursor trigger to a different synoptical set up as we move through early Feb.

In the meantime its more of the same, a quieter week ahead than the last one, less stormy but still very mild with a westerly/south westerly flow. 

Edited January 26 by damianslaw

[Gowon]

A few shortwaves in the flow there

[Mike Poole]

11 minutes ago, IDO said:

The 12z suggests the tPV is losing momentum in FI. D15:

A bit wedgy. Maybe changes as we move towards mid-February?

Yes, it does seem from the modelling in this range that the force driving the westerlies peters out.  But there doesn’t seem to be any strong blocking pattern to follow it.  Nothing consistent that I’ve seen from the op runs and ensembles.  We could drop lucky with a wedge, for sure.  But I am still expecting to see more evidence in our sector of the +AAM and MJO into favourable phases than I’m seeing - it could just be a bit too early.  

Edited January 26 by Mike Poole

[Lukesluckybunch]

Whiteout conditions at the end of the gfs run!if only ..gfs mean absolutely useless at days 8-10 strong heights to the South of the uk!

Edited January 26 by Lukesluckybunch
Adding

[Gowon]

A ridge building into Greenland from north America which wasn't there on the 0z:

[Chesil View]

Ecm 12z op singing from the same hymnsheet as Gfs 12z op at 240. 

[blizzard81]

Very positive developments today. I still think we won't have to wait until the second half of Feb for the best spell of winter. I think the Exeter updates over the next couple of days will bring that forward to more early Feb rather than mid. 

[Rob 79812010]

Really hope you're right but am thinking second half at this stage

[nick sussex]

Some changes are looking likely as we head into February.

I think likely helped by the movement of the MJO.

The westerly flow does look to slow and the limpet high looks like being flattened with the jet heading further south .

Its probably best to reserve judgement as to what to expect in terms of cold prospects as the models are only just catching onto those MJO induced changes upstream .

It’s a start at least .

[WYorksWeather]

Hate to put a downer on things, but I'm really not seeing what the excitement is all about really in here with tonight's 12z.

Even cherry picking a more northern location, all you can really say beyond the first few days of February is that we move towards no signal for temperature. Both OP and control were on the colder side of the ensemble, and there really aren't that many members that get below -5C at 850hPa, even in the north.

For comparison, these were the ensemble means we were seeing around 10-12 days out from the cold spell from the 15th-20th February:

As others have said, there's only been one bust on the ensemble means this winter, which was in mid-late December, and the cold spell got downgraded. If there is going to be a cold spell around the second week of February, we need major upgrades over the next few days.

One control run and one OP run does not a cold signal make.

 

[sebastiaan1973]

EC46 shows some love for the winter lovers with northern blocking.

 

[Mike Poole]

ECM clusters this evening are starting to develop something more interesting.  T192-T240:

While cluster 1 remains zonal, and cluster 2 shows a brief collapsing ridge, cluster 3 develops a much more substantial Atlantic ridge, albeit with only 5 members.

T264+:

Cluster 3 is the obligatory zonal cluster, but the others are more interesting, with some kind of ridging in the Atlantic on clusters 1 and 2, and the appearance of a proper Greenland block (for the first time) on cluster 4 (8 members) - one to watch… 

Edited January 26 by Mike Poole

[Dennis]

EC 3 febr

the days of cold air shows up ...time to get into a MJO 7 ....with a strong GH

 

 

Edited January 26 by Dennis

[Mike Poole]

  @sebastiaan1973 Yes, the 46 showing a strengthening signal for blocking in the Greenland area w/b 12th Feb, last 6 runs:

The low pressure anomaly into Souther Europe is stronger too - that blue wasn't there yesterday.  

We need to see this signal start to show more strongly in the EPS over the next few days, building on the excellent cluster 4 in the extended on today’s 12z.  

[bluearmy]

Been quite an interesting day then 

 

[Dennis]

give it a try on GH 

[mountain shadow]

  @Dennis I love these signals and I would say they are great for cold and snow for you.

For these islands that make up only 0.05% of the surface of the earth, the cold air can quite easily slip into the Atlantic or through Scandinavia and miss us completely. 

[Dennis]

  @mountain shadow

true its not easy in the UK  , a retro signal is needed or an arctic flow 

febr is seen as better than the Jan24 coldspell, updates follow on part2 soon 

 

[WYorksWeather]

ECM mean is no better than average into deepest FI.

As other shave stated, ECM extended looks better of late.

Temperatures near average for the UK from 12th-19th - we need to hope this resolves to below average.

For comparison, CFSv2 is much less favourable for mid-February. Week 3 (9th-15th) is very mild, week 4 (16th-22nd) is still on the mild side but less so.

And finally, the GEFS 35 day shows a brief colder spell around 13th-19th on the mean.

Always somewhat sceptical of the extended range output, so think it is only fair to put a few different versions up there. In short, there's not really much agreement. The EC46 is generally most trustworthy, but it is a case of best of a bad lot.

The key warning I would give is that we constantly see cold spells in FI or in the sub-seasonal models being pushed back or downgraded. It was only a couple of weeks ago that the whole of February looked great on the models, now we're increasingly looking closer to mid-month.

We really need some sort of forcing to come along, be it the MJO, an SSW, or something else, to give the atmosphere a giant kick to break us out of the current rut.

 

[Dennis]

Ok to some ideas from the strato : we have had an reversal sign around 15-17jan (10Hpa)

after that we need to see some called downwelling from the stratosphere....and thats seen very soon in the tropshere/atmosphere  first time around 1-5 febr 

but thats the first step ,

 

 

 

Alaskian Ridge (seen also as a Canadian warming) is forcing the Vortex to Russia over the worldmap

part 2 is seen later the month

 

Edited January 26 by Dennis