Model Output Discussion - Spring Has Sprung

[Marting]

The ECM ensembles are becoming rather chilly and fairly concentrated on the meteogram

[northwestsnow]

EC 46 looks really good.

 

[Lukesluckybunch]

For london.. the op wasn't even outlier!

[That ECM]

 northwestsnow are you referring too 850’s?

I would say a little less cold 

[mulzy]

 That ECM I think @northwestsnow is probably referring to the push of more marked higher heights to the north and northwest on the 12z EPS.  Synptically it looks better than this morning.

Edited February 3 by mulzy

[Mike Poole]

ECM clusters, T192-T240:

Custer 2, which contains the op and has 22 members shows developing high pressure to NW possibly linking to NE.  Cluster 2 a modest wedge of high pressure, but well placed.  Cluster 3 similar to NW, but a low camped west tending to re-inflate Southern Euro high.  Cluster 4 heights getting sucked north through the UK.

T264+:

Er, just bank, please.  All of them!  Clear trend to a northern block, clusters 1 and 2 centred south of Greenland, cluster 2 has NE’ly over UK.  Cluster 4 extends the high east and brings in easterly.  Cluster 3 just drags its heels with surface high pressure close to but west of UK.

Major upgrade tonight!

 

Edited February 3 by Mike Poole

[That ECM]

 mulzy yes that’s better.

[Due South]

 MAFwhat you mean is. Show me the chart, because i can't be bothered to look myself

[Mike Poole]

ECM 46 looking good re pressure patterns.  Zonal winds:

Fewer members today going for the  technical SSW than yesterday.

This chart suggests we’ve made it into phase 8 on the actual data.  The model would have us back in phase 6 by day 5, but I remain suspicious of that!

Edited February 3 by Mike Poole

[stodge]

Evening all

A lot of eye candy on offer tonight - the 12Z GFS Control takes the cold potato award with classic retrogression which of course never happens.

The key seems to me the build of heights in mid Atlantic after the LP has gone through the British Isles - doubtless rain for lowland East London but I'd like to think someone somewhere to the north and especially with some altitude is going to get some snow.

Huge amounts to be resolved and GEM OP shows what a non event would look like.

The 10 HPA charts suggest a stratosphere in some distress and the expulsion of the vortex shown on the 12Z GFS Control is a thing of beauty. 

[Uncertainty]

There’s been a real sea-change in the output tonight in the 7-10 day range, regardless of what happens with the will it won’t it north / south Thursday low.

The heights to the N of the U.K. seem more to just build spontaneously, rather than be reliant on WAA from a stalling Atlantic low. 
 

It’s apparent across the 3 main models.

GEM 0z

GEM 12z

Notice the Azores low is now squashed. Heights are rising to the W and N of the U.K. - though the shortwave W of Iceland could be an (academic) nuisance.

ECM 0z at day 10

On the 0z ec, we are reliant on the Atlantic low to build the ridge through the U.K. and on to the NE if we’re lucky…

On the latest ec 

Completely different. The Atlantic is spilt  into two jets, the sub tropical jet is sending multiple squashed lows towards Iberia whilst the northern arm builds the Icelandic high. A much rarer scenario than the above and one I’m more familiar with from archive charts than from my own forecasting experience.

What does this mean? Are there models ‘seeing’ the road to northern blocking the ec46 has so consistently promised? I think they are. And there are other factors driving this transition to a colder paradigm:

- modelling is picking up on a much weaker strat than anticipated a few days ago, though an ssw looks 50/50 and the strat has been weird this year and you wouldn’t want to call it yet.

- the mjo is forecast to stick around somewhere in phase7 and(possibly) onto  8. A good sign for cold weather 

- the massive AAM surge and accompanying  +EAMT favours blocking patterns, especially  when the above factors are in play 

 

- The ec has been incredibly consistent. As consistent as I’ve ever seen it, even taking into account the daily runs 

It continues to advertise a marked cold and blocked spell. Indeed, the colder than average temps are back tonight too.

When looking for significant pattern changes in My personal forecasting area - the 10 to 15 day range - I look for a mean high in an unusual place to persuade me that a signal is genuine. The geps has had this for a few days but now the other two have cottoned on:

GEM: mean easterly with a Greenland block and S euro low

GEFS: a highly anomalous North Sea high with a flow from the east in the S

This retrogresses to a NEerly

The eps is still pouring out. But @Mike Poole assures us the clusters are bankworthy and he knows his clusters.

Unsurprisingly, he’s not wrong. They are sensational for cold with a eurolow of some description and varying degrees of blocks to the N.

So is it a done deal? Ha. Of course it isn’t. We’ve been here before and further and still had everything bust. BUT… you can’t deny the incredible synergy between the telecons and the models - and particularly the consistency of the sub seasonal modelling.

In conclusion. It might, just might, be time to…

 

buy more grit! 

 

Edited February 3 by Uncertainty

[Wold Topper]

 Due South or perhaps quantify one's post with more info than one line of text?

[Spah1]

I’m getting a little tired of reading lazy analysis. Probably since around 2013 and various wedge events folks on here throw out ‘it will get corrected South’ whenever we have a low pressure system hitting colder air. I’m no expert but it seems to me that these systems do get corrected South but only when the models underestimate the block or wedge the low pressure system is disrupting against. In Thursdays scenario I can’t see a wedge pushing the LP South that the models are underestimating. Someone with way more knowledge than me may correct me but that’s how I see it. 

[feb1991blizzard]

 northwestsnow

Eps also an absolute stunner, cold all the way on the 850's graph, greater longevity than recent suites, as showing on Mike Poole's clusters post.

[northwestsnow]

 feb1991blizzard I'm really excited up here mate !!

It's beginning to look very very interesting.. 

[Purga]

A very good set of ENS 12z for ECMWF for extended cold trending better than 0z.

 

[feb1991blizzard]

 northwestsnow

Make no mistake if anything spectacular happens on a weeknight, i'm there Granby & tory club, don't care if i have to sleep on Saddleworth moor in blizzard conditions.

[Uncertainty]

Don’t think I’ve ever posted a single non-op perturbation before but…

Eps control…

Hopefully you’ll understand why I chose this one!

Edited February 3 by Uncertainty

[northwestsnow]

 feb1991blizzard blizzards would be lovely and it's not out of the question if we do swing an Easterly ...

fasinating viewing and this evening has gone very well..

[Jacob]

 Uncertainty Bye bye Gulf Stream and say hello to extreme cold flooding in from Siberia which can’t be stopped by westerly winds!!!

[Allseasons-Si]

 Uncertainty

i prefer the NH view,...stunning

and what follows i dare say is from the NE a few runs later,...yes it's jff in fl but other models are picking up on this signal.

[johncam]

 Uncertainty if you look at the 850' s not great coming in from North sea , snow high ground , all academic though that far out.

[minus10]

Thats more like it!!

 

...yes in la la land but how often do you see a chart like this from any model ?

....nice to look at anyway...

 

[WYorksWeather]

Interesting ensemble runs tonight. Until recently we've been seeing GFS showing more cold potential than ECM as a rule, and tonight it's the reverse.

Still a striking amount of variation as well. On the negative side from a cold perspective, there's not a lot of runs showing very deep cold to guarantee snowfall (-10C 850hPa or lower), and there is also some possibility of a more significant warm sector around the 8th-10th even further north, which would probably wash away any snow.

However, on the positive side, there are a not more runs going for a longer cold spell, with some chance of temperatures remaining significantly below average until around mid-month, possibly beyond.

In terms of meteograms, I think for the south it's a tall order to get snow down to low levels with this - temperatures still in the 5C range by day even on the coldest days going by the mean for Reading. For Newcastle, maxima could get down to around 2C, which gives a much better chance of precipitation falling as snow in the first place, and then remaining on the ground for a while.

The wind plumes also show the uncertainty, though it is clear that the models are now latching on to an increased chance of northerly winds in the extended. Still some variation, and small changes will matter. A north-easterly could make things very cold, whereas a north-westerly would be more the default winter option - a little colder than average, likely mostly rain and sleet away from high ground.

Details still, even at this stage, too fine to be worked out.

Again, we've seen this before, so as long as milder options remain in the ensembles I'd be loathe to dismiss them, even though they're not what we want to see. Definitely an upgrade tonight though compared to last night.

Still more time to go on the sea surface temperatures as well. T+0 for the North Atlantic vs. T+360 is below. As long as these are going down, it's not over yet.

In anomaly terms, the Azores warm blob remains for the foreseeable, but nothing too out of the ordinary in our immediate vicinity. If anything, a cold anomaly to our north and east, which may be useful to us if we do get a second bite of the cherry in the second half of February. Again, wild swings possible from cold to very mild.

 

[bluearmy]

I can’t see Thursdays system correcting v far south unless the phasing in the Atlantic changes significantly. As this is only day 3/4 I’m afraid those hoping for a notable correction south are likely to be disappointed.  Still a day for a wtf moment but it’s a long shot