Model Output Discussion - Deeper into Autumn

[northwestsnow]

GFS day10

EC day10

Massive difference in the Atlantic.

GFS = energy southern arm

EC = energy in northern arm

If I were a betting man I'd say a UK high is a good bet ,which could introduce some frost fog etc..

Initially at least  obviously we want to see the High shift North.

I'm not convinced there isn't too much Atlantic  energy on EC to get that high North enough but anyway its day 10 so probably meaningless at this point..

Edited November 21, 2022 by northwestsnow

[Duane S.]

Great set of 00z charts. Oozing with potential. Great GFS, Parallel and Control and nothing wrong with how the ECM evolves, just another variation within the envelope. There are far worse possibilities from this set up, from which a cold spell is far from nailed on unfortunately.

This is the area I’m focusing on as a catalyst, seems to be reasonably good model consensus on it, fine details to follow…

 

[IDO]

The GFS op and control go into outlier territory from D8 (London):

So at the moment, that scenario looks a long shot. 

The GEFS mean remains solid with the tPV moving mostly to the Asian side, so the Greenland heights should re-establish (mean D8-16):

So assuming this clear signal is correct, heights have every chance to rise in our region. Let us see if the higher res op and control are onto something. The potential is good.

[Blessed Weather]

 Great model watching atm. Looking at the 0z GFS forecast at T240 the Op certainly has support from it's 31 member ensemble. And the suggested solution of high pressure to the NW of the UK is a good match for the MJO Phase 7 composite for Dec in a Nina year.

[Met4Cast]

The 00z GFS is broadly in-line with my expected pattern come early December. Warm Air Advection (WAA) through the UK essentially pumps high pressure up like a balloon, initially very mild but we then see retrogression opening the flood gates to colder Arctic air.

Don't take the above charts here literally, it's just a single run of a single model well outside of what's reliable. I'm just using these charts to illustrate the above thinking. It all starts with that WAA, without the WAA there is no blocking, but this is the broad pattern I've been talking about/expecting to start seeing. 

A lot of chopping & changing to come and we could end up with blocking in a place that's unfavourable to UK cold, but blocking is likely & expected in early December.. we just need to wait & see where.

Hows this for a mean though! The PV has completely drained away from Greenland.

Edited November 21, 2022 by Met4Cast

[sheikhy]

Give me gfs all day long this morning!!i mentioned the 168 to 192 hour timeframe yesterday as that is where it all unfolds nicely and the same thing is shown on the gfs this morning!important thing is everything falls into place so much earlier on gfs compared to ukmo and ecm!!i aint interested in day 10 forget that!gimme something that crops up at 168 hours or earlier and i be paying attention!

Edited November 21, 2022 by sheikhy

[northwestsnow]

1 minute ago, sheikhy said:

Give me gfs all day long this morning!!i mentioned the 168 to 192 hour timeframe yesterday as that is where it all unfolds nicely and the same thing is shown on the gfs this morning!important thing is everything falls into place so much earlier on gfs compared to ukmo and ecm!!i aint interested in day 10 forget that!gimme something that crops up at 168 hours or earlier and i be paying attention!

Yep GFS 00Z MUCH preferred option.

Let's see how EC clusters look...

[sheikhy]

Just now, northwestsnow said:

Yep GFS 00Z MUCH preferred option.

Let's see how EC clusters look...

It just looks so much smoother mate and the process actually starts at 144 hours which is exactly what we want!!i dont think it will happen as the gfs shows cos me and you know damn well that would be extremely luky for us!!!lol!!i actually think all models should go out to 168 hours max as thats well within the reliable in my opinion!!!

[Met4Cast]

Decent ECM day 10 mean too.

Not quite winter wonderland for the UK but the EC is in agreement with the GFS when it comes to shifting the PV towards Asia, if this doesn't happen then any blocking in the Atlantic/Greenland sector will just get flattened. 

Baby steps.. 

[Mike Poole]

ECM clusters, well there is a lot of uncertainty early on, but it is uncertainty within an envelope that is pretty much comprehensively blocked.   

Looking longer term, T264+, 3 clusters:

I’m looking long term here, because this does now have the potential to be a spell of weather that sets in for a while.  The amount of blocking shown is significant, even if the details vary.  Cluster 2 looks very nice, with a cross polar block through Greenland yielding a northerly.  Cluster 1 could see the whole northwest blocked, much potential from there.  Cluster 3 has the UK within a block extending north, so dry and home grown cold with that one.  

[northwestsnow]

I'm guessing DET was in cluster 1 Mike?

 

[Met4Cast]

1 minute ago, Mike Poole said:

ECM clusters, well there is a lot of uncertainty early on, but it is uncertainty within an envelope that is pretty much comprehensively blocked.   

Looking longer term, T264+, 3 clusters:

I’m looking long term here, because this does now have the potential to be a spell of weather that sets in for a while.  The amount of blocking shown is significant, even if the details vary.  Cluster 2 looks very nice, with a cross polar block through Greenland yielding a northerly.  Cluster 1 could see the whole northwest blocked, much potential from there.  Cluster 3 has the UK within a block extending north, so dry and home grown cold with that one.  

Importantly this scenario is backed by the background signals, I've mentioned it on here a few times and I know @MattHhas been discussing it too.

The current Scandi blocking episode failed because there's too much westerly momentum at the moment, the Atlantic jet is active fueled partially by the recent cold plunge across America but also by the SPV imprinting on the trop over Greenland. 

That westerly momentum has decreased & importantly we're beginning to see easterlies in the mid-high lats along with a signal to remove the PV from Greenland and shift it towards Asia. 

These two things combined with the falling AAM should help to promote blocking into the Greenland/Atlantic locale and that's now trickling into the NWP outputs too. As ever UK detail remains elusive and whether blocking ends up being favourable for us is with the weather gods currently, but a blocked early-mid December is the most likely outcome.

Exciting..

[Frosty.]

The longer term ECMWF 0z ensemble mean carries on from where yesterdays 12z left off with high pressure / ridging gradually replacing low pressure…a more seasonal settled start to the meteorological winter is a good bet with overnight / early morning mist & fog and frost clearing to variable cloud and sunny spells. ️ 🌫….fingers crossed a spell of high pressure would then be followed by an early taste of proper wintery weather, or is that too much to ask??  !  

 

Edited November 21, 2022 by jon snow

[Mike Poole]

3 minutes ago, northwestsnow said:

I'm guessing DET was in cluster 1 Mike?

 

Det finishes at T240 so is not placed in the T264+ clusters.  

[Decemberof2010]

34 minutes ago, Met4Cast said:

The 00z GFS is broadly in-line with my expected pattern come early December. Warm Air Advection (WAA) through the UK essentially pumps high pressure up like a balloon, initially very mild but we then see retrogression opening the flood gates to colder Arctic air.

Don't take the above charts here literally, it's just a single run of a single model well outside of what's reliable. I'm just using these charts to illustrate the above thinking. It all starts with that WAA, without the WAA there is no blocking, but this is the broad pattern I've been talking about/expecting to start seeing. 

A lot of chopping & changing to come and we could end up with blocking in a place that's unfavourable to UK cold, but blocking is likely & expected in early December.. we just need to wait & see where.

Hows this for a mean though! The PV has completely drained away from Greenland.

Excellent post and easy to understand. Thanks for the effort you put into it

[Frigid]

GFS 0z ensembles trending much cooler with the mean starting to fall below the long term average. OP not really an outlier in this suite, many ensembles as well as the Control run under the -5c mark. I'd love if it evolved to this! 

[tight isobar]

Well.. the dark runs .. all I can verb atm , is.. they’ve all got “ smashing blouses on”!!!.. we’ll ava look where we head in todays outs

[Ali1977]

6 minutes ago, Frigid said:

GFS 0z ensembles trending much cooler with the mean starting to fall below the long term average. OP not really an outlier in this suite, many ensembles as well as the Control run under the -5c mark. I'd love if it evolved to this! 

FI starts at day 8 according to that, let’s hope for more to drop below -6c as the next few runs trickle in. That’s probably the best set so far this month, that’s not saying much though. 

[Anthony Burden]

Morning all,The excitement beginning to build as I stated in my blog yesterday position and orientation of high pressure the key to every door regarding cold / very cold weather.I have said this before but hats off to Exeter and Glosea for predicting this pressure rise at the end of this month,time wise around 3 weeks to a month in advance some achievement.We now hope for winter to show it’s face with some of the white stuff thrown in the mix.

[ANYWEATHER]

Oh here we go..... Really wish sometimes we had just one model to look at! Ecm drops the idea of a Scandi high and gfs throws the solution up How many times do we see this scenario. .? 

[Downburst]

Interesting to look at Stockholm, as the high ridges on this side, low pressure moves in over Scandinavia, but as is expected there is a lot of spread after 6 days. I think it does have a good chance of happening though, it has a flow to it that doesn't jar too much. And as someone showed the composite for MJO phase fit this. And it can't just keep raining all the time

[TSNWK]

Mmm 06z not going the scandi heights root... a tentative attempt at ridging to northwest that looks like it will be flattened...

Next? 

Gfs // more appealing to my eye with azores ridging over us and into scandi

Edited November 21, 2022 by TSNWK

[Liam Burge]

5 minutes ago, TSNWK said:

Mmm 06z not going the scandi heights root... a tentative attempt at ridging to northwest that looks like it will be flattened...

Next? 

That is a strong block. Not getting flattened yet.

Edited November 21, 2022 by Liam Burge

[Ali1977]

11 minutes ago, TSNWK said:

Mmm 06z not going the scandi heights root... a tentative attempt at ridging to northwest that looks like it will be flattened...

Next? 

Maybe that set up always was a little early, and we should just be looking to what happens around day 10-12 , FI is definitely early but that might have something to do with the MJO changes. 
The last 2 runs are pretty similar by day 9 to be fair , apart from the PV being stronger on the 06z

Edited November 21, 2022 by Ali1977

[DavidS]

Looks promising to me. This at 210