Model Output Discussion - Spring Has Sprung

[Marting]

Quite a big shift in the ECM average at day 10 tonight, vortex shifting to scandi akin to gefs

[Don]

@Metwatch The uppers look less mild on that chart than some being modelled tonight though.

[Metwatch]

4 minutes ago, Don said:

@Metwatch The uppers look less mild on that chart than some being modelled tonight though.

GEM usually goes a bit overboard with the 850s by 2-3C, others seem to have a ceiling of 8-10C.

Edited January 23 by Metwatch

[sebastiaan1973]

 Change is coming according to EC46. Northern blocking in the second half of february. MJO enters phase 6, then 7 losing amplitude. Spread is big. 

[Mike Poole]

ECM clusters T264+:

Well, there’s something still there in this timeframe, with various takes on an Atlantic ridge, cluster 3 looking the most convincing, but I’ll believe it when I see it, I think.  The 46 dayer - the signal looks to be getting weaker there too.  If all our eggs sit now in the MJO basket, then we really are up against it expecting that fickle beast to behave itself…

The upcoming weather holds little interest for me, so I’ll take a break from model watching for a few days.  

[Singularity]

I approve of the ECM 12z for showing how a strong high with well above normal 850s across the UK can be part of a hemispheric pattern that increasingly disrupts the tropospheric polar vortex. As of D10 the door is finally starting to open for the high over Europe to shift quite a way northward.

Strange that GFS was also doing that sort of thing on-and-off a few days back but has consistently failed to sufficiently, ahem, ‘un-flatten’ the polar jet during the past 8 or so runs. Ah well, at least GEFS are starting to explore the idea more.

[Singularity]

@Mike Poole cluster 1 is a good signal for a -NAO of the Iceland-focused variety which can actually be on par with a full on Greenland high for cold UK weather, though it tends to be in the drier side.

Overall, the signal for the long indicated change is a starting to grow as anticipated. Just needs to sustain for a few days in order for confidence to begin increasing.

[Mike Poole]

@Singularity Well maybe, but I think there are too many possible pitfalls to be confident of the signal from mid-February to actually still be a thing by the time we get to mid February.  An MJO fail certainly looks possible, and the strat vortex looks to be gathering in strength for the first time in winter, if that gets placed badly and starts to really rule the roost, then it could wipe out the rest of winter.  We will see…

[bluearmy]

If eps 00z are as enthused on Atlantic ridging as the 12z then assume the 46 might be a bit better tomorrow.  Whilst the models are no longer the same at day 15 you’d assume that there must be some synergy 

[winterof79]

Going in the right direction i feel

 

[WYorksWeather]

If you'll allow me a bit of humble-bragging - my prediction of the potential for a new date record being set around the 22nd-24th January has come off, with an apparent 15.4C at Rostherne No 2 today beating the 15.2C at Westonzoyland in 2018.

Here's my readout on the latest EC46, whilst we wait for the complete ECM ensembles later.

Week 1 (29/01 - 05/02)

At least 3C above the ECMs climatology, which is roughly an average of the last 20 years.

Week 2 (05/02 - 12/02)

Less mild, but still 1-3C above average.

Week 3 (12/02 - 19/02)

Continues the trend, near normal or slightly above average (<1C), though add half a degree if you compare to 1991-2020, maybe 1.5C for 1961-1990 given rapid warming in February.

Week 4 (19/02 - 26/02)

Almost no signal for temperature now.

Week 5 (26/02 - 04/03)

Same again, pretty much an absent signal.

Summary

Overall, I think a very mild first week, and possibly first half to February is very much favoured. At this stage though, I do feel it is a bit premature to write off the rest of the winter. The signal does at least weaken for mild towards the end. We would want to see that replaced by a stronger cold signal of course in the next week or two.

I say we hold fire for about two or three more weeks before calling it. If we get to mid-February and there's still no change in sight on any of the models, then I think we call it game over, because we'd expect to see a strong signal for cold in late February or early March by then if it were on its way. It would also mean a massive bust for the seasonal output.

In the meantime, the rest of January and early February looks very spring-like in terms of temperature. Time will tell if this is an early spring, or a false spring...

[Eagle Eye]

The second half of February was bigger to me than the first half pretty much with a mid Feb change, quote from Thursday I think;

"that could well have a significant response by mid February here. For now, the best we're looking at is the rising GLAAM and phase 5 ish response. However, the +VE IOD collapse has aided the potential for a larger MJO-GLAAM tropical and subtropical forcing for that mid-month ish potential.  "

I did expect a semi-good signal for early February but that's appearing unlikely. However, mid February perhaps later towards March given how delays have been recently is the next potential. It's a large pattern to get rid of though. 

Edited January 23 by Eagle Eye

[WYorksWeather]

Anyway, whilst I was typing that, we now have the ECM ensembles. Here are the mean charts at days 5, 10 and 14

  

  

Some progress on the mean chart by day 14, but hard to tell how much is just averages flattening out in the extended. It can't go on raging mild all the time, but let's face it we're only getting the 0C line in even if this verifies. With the real cold at -8C well away to our north and east, about the best you could hope for from that is some overnight frosts and fog and maybe some hill snow.

 

[Daniel*]

Hmmm this is a start, it’s been looking dire for ages…. the return of -NAO in early Feb?

 

we can also see the stratospheric vortex looks to be more shoved away from North Atlantic into northern Russia thus more blocking opportunities for -NAO I’d say.

 

MJO forecasts also consolidating on phase 7. I expect we will have some better output on the way very soon.

[AO-]

@WYorksWeather

For my location it has improved a tad since this morning. The frosty nights are caused by a mobile ridge or temporary influence from the Euro high. 

This morning

Tonight

[WYorksWeather]

@Eagle Eye For what it's worth I agree - too much can change in a short time to be writing off anything into the second half of February. Temperatures don't really start to rocket up until early March, as I discussed in more detail a few days ago.

It can simultaneously be the case that the short to medium term output is woeful from a cold perspective, but that we can still have another roll of the dice later in February or into early March.

If we get to mid-February and no cold on the horizon, though, I'm going warm ramping and beginning the hunt for the first 20C of the year 

The key tipping point will be when we start generating home-grown warmth again. Once we get to the point where a UK high is warming in situ rather than cooling, we're done as far as winter is concerned.

Seas still cooling down to day 15 though. Until this turns around, we're still in the game.

 

[Rain All Night]

8 hours ago, RainAllNight said:

Deterministic runs, Tue 23rd to Tue 30th

Ensemble means, Tue 30th to Tue 6th

Bonus

If this is how it's going to be, then I hope we might at least do it properly!

Deterministic runs, Wed 24th to Tue 30th

If it weren't January, then there might be some more interest in what the low pressure that appears in the Atlantic on Sunday will do... most of the models send at least a part of it to the southeast to become a cut-off heat pump low... "lol". Some have it kicking a surface high over the UK too.

Ensemble means, Wed 31st to Tue 6th

It looks as though "peak bulge" over the UK may be Wednesday & Thursday next week, offering us benign beginnings to February. By that weekend, we see the lowest heights to our northwest having migrated to our northeast, perhaps indicating the possibility of a cooler pattern emerging?

Edited January 23 by RainAllNight

[stodge]

Evening all

As I often say, the route to very cold usually starts from very mild with the displaced Azores HP serving to put pressure on the vortex enabling other events and factors to come into play.

Given the focus of LRFs was on a back-loaded winter, I fully expect a cold early March which will annoy many but the weather does what it does. 

[Don]

The 500 hPa chart did not look great last night for the 12th-19th February, with pressure high pressure remaining too high over Iberia.

However, I would say it looks worse tonight with high pressure not retrograding into Greenland as much and heights even stronger to the south. 

Charts for the following two weeks look ok, but yet again, the interest is being pushed back!

 

Edited January 23 by Don

[blizzard81]

Hmmmm.... Ecm and ens throwing an interesting curve ball this evening which is nice. Also in tandem with a fair few of those gfs ens. We haven't seen much (if any) upgrades in the modelling at relatively short range this winter. It would be nice to see this continue tomorrow and maybe even see Exeter revert back from their delaying of the cold in tomorrow's update. 

@Don That's from the 00z suite though.

[blizzard81]

@uncertainty - could you please give us some more certainty in your next post

[Uncertainty]

@LRD I think the anomaly shows just how dire Februarys have become as a slight ridge to our w looks like major retrogression when it ain’t. I always look for a mean flow from a direction without a W in it to get really interested. At the moment the 12z eps are intriguing but still a mean westerly and thus a watching brief only. The positive from tonight’s runs is the drain of purples from the mean charts away from Greenland. There are lots of good ensembles, but again not enough to suggest a clear cold trend.

[blizzard81]

I much preferred it when you could reply 'directly' to a post so people could see without having to trawl back at what is being replied to. 

[Rain All Night]

2 minutes ago, blizzard81 said:

I much preferred it when you could reply 'directly' to a post so people could see without having to trawl back at what is being replied to. 

You can still do it if you select the text and click the "Quote Selection" box that pops up, a bit like you would do copy and paste on a smartphone

[bluearmy]

Plenty of despondency this evening 

I actually think this ties in with the best set of eps in the 12/15 day period that we’ve seen for some time 

There are also some ops and control runs which look to have a very mashed tpv in fi 

the darkest of the night is just before the dawn …….  I think