Model Output Discussion - Christmas week and beyond

[Mike Poole]

32 minutes ago, Battleground Snow said:

It's like the models have been underplaying the mjo influence and are now reflecting it the nearer we get..

Remember a couple days ago the scandi high was brushed away with ease, now it's trying to disrupt a piece of the vortex 

Yes, they do seem to have been doing that, the models were predicting MJO close to or in the COD through 6 and 7 a week or so ago, and now literally the case of them smelling the coffee, and finding it a bit more caffeinated than they had thought.  

I’m not sure we are anything closer to finding out how this pans out, a signal for amplification is becoming apparent across the models, but where that means the ridges build is dependent on the detail of each run with regards to placement of the smaller scale lows etc., so remains very unclear.  I thought this run might be flirting with Greenland at one point - it didn’t, in the end, ended up UK high in far FI.  But a reasonably potent northerly considering the set up at T240:

Edited December 31, 2022 by Mike Poole

[mushymanrob]

The latest cropped EPS for Jan 15th.... signs of building heights over Northern Scandinavia and troughing from the baltic right down to Africa... this suggests below average to me, with the signs of something colder emerging IF the signs continue to build (and not simply fade). After this weeks mild unsettled, id have thought cold unsettled would be the theme... in fact it reminds me of early 1984, when a pattern of Polar Maritime air (the ops are suggesting) brought quite a lot of snow to northern and Western areas..

[Mike Poole]

T354:  Hmmm…

Over +12C there!

[feb1991blizzard]

1 minute ago, Mike Poole said:

T354:  Hmmm…

Over +12C there!

Get in !

[ICE COLD]

That’s gotta be the biggest warning yet on the gfs 6z ??? 

Edited December 31, 2022 by ICE COLD

[bluearmy]

Just now, ICE COLD said:

That’s gotta be the biggest warning yet on the gfs 6z ??? 

Very different to previous runs 

want to see what happening at all levels to judge why 

[That ECM]

Just now, bluearmy said:

Very different to previous runs 

want to see what happening at all levels to judge why 

Well at ground level @feb1991blizzard is running around very excited.

[feb1991blizzard]

3 minutes ago, That ECM said:

Well at ground level @feb1991blizzard is running around very excited.

yes - need to see the heights charts first though - see if its a displacement and if so where to and if its susceptible to a split.

EDIT : need to see if chiono is getting excited 

Edited December 31, 2022 by feb1991blizzard

[bluearmy]

1 minute ago, That ECM said:

Well at ground level @feb1991blizzard is running around very excited.

The displaced svaalbard option was doing ok. Not sure we want a complete rethink unless that warming can be sustained.  As I said, so very different to previous runs and the eps mean so likely discounted for now with a mental note. 

[Derecho]

Morning all, those heights over Svalbard that appeared on the odd GFS operational a few days ago now appear to be playing their hand more

Here we can see a distribution of T850s over southern Sweden for the EC ens this morning, the EC OP isn't even the coldest solution with some very cold members in there.

We of course are looking at some Polar Maritime air, however if we can get deep cold into Scandi then trough disruption could mean lower heights a bit further south in central Europe, rather then Scandi. We look to get some chillier uppers anyway but if we can see some good changes downstream, that will have a butterfly effect for later on.

Here is some suitable ens members....

 

Lets see what happens! 

 

 

Edited December 31, 2022 by Quicksilver1989

[CoventryWeather]

I got confused 

Edited December 31, 2022 by CoventryWeather
Wrong stuff 😅

[feb1991blizzard]

1 minute ago, bluearmy said:

The displaced svaalbard option was doing ok. Not sure we want a complete rethink unless that warming can be sustained.  As I said, so very different to previous runs and the eps mean so likely discounted for now with a mental note. 

was some support on the GEFS 0z although nowhere near as agressive.

[bluearmy]

2 minutes ago, CoventryWeather said:

Northern Hemisphere charts seem very interesting - you can faintly see where the split is going to occur. That looks like an SSW if it continued for another day or so.

Not sure how you can extrapolate from that to an ssw ?  Unless you mean the 10hpa chart and there wouldn’t be any connection at the same time between 10hpa and 500hpa. Maybe I’m misunderstanding 

[keithlucky]

24 minutes ago, feb1991blizzard said:

yes - need to see the heights charts first though - see if its a displacement and if so where to and if its susceptible to a split.

EDIT : need to see if chiono is getting excited 

Strat Warming has been forecasted for while,With a complete split of the Polar votex ,we need to see consistency with model output with a zonal reversal with east wind moving from Siberia to UK .

[CoventryWeather]

24 minutes ago, bluearmy said:

Not sure how you can extrapolate from that to an ssw ?  Unless you mean the 10hpa chart and there wouldn’t be any connection at the same time between 10hpa and 500hpa. Maybe I’m misunderstanding 

Don't worry - I'm new to this stuff. Sorry if I've confused anyone.

[Ali1977]

43 minutes ago, ICE COLD said:

That’s gotta be the biggest warning yet on the gfs 6z ??? 

Will the METO long range change the wording if this was showing on their models I wonder!! 

[Don]

3 minutes ago, Ali1977 said:

Will the METO long range change the wording if this was showing on their models I wonder!! 

Not just yet I wouldn't have thought, but would obviously keep a close eye!

Edited December 31, 2022 by Don

[Allseasons-Si]

Although the 06z gfs is different up top to it's previous run,it does show a near split(altough stretched at this point) of the spv,let's see what future runs produce...

Looking at the 06z gfs for example,you can see the difference from yesterday mornings run at 168 vs this morning run at 144,notice how the heights over N Scandi have moved/backed west into the Norwegian sea putting more preasure on the trough out to our NW,notice how sharper/neg tilted it is

it would be interesting to see how this play's out,can we get more forcing of the trough SE from this wedge of height's to our N/NE,an interesting one to watch.

 

[nick sussex]

The GFS 06 hrs run picks up the UKMO baton and almost makes the finishing line ! 

Remember that UKMO tweak I was hoping for , we just need another little tweak this evening ! 

You can see by the ECM ensembles that the mean keeps the rounded troughing and if the ensembles were more bullish on the sharper troughing we might have seen more colder members .

Could there be a dramatic development this evening ?

 

[E17boy]

Hi peeps

Hope you all had a lovely Christmas . 
Certainly some rumours flying around now of a freeze to develop as we go through January  but all to be taken by a pinch of salt. However the models since yesterday have certainly made me come out of hibernation.

Seems to be some positive developments going on. A week ago it was all doom and gloom and January had been written off by many. Are we about to see something special develop as we head into the new year who knows it may not come to nothing, but certainly something interesting maybe brewing. All eyes on developments in the coming days.

Wishing you and your families a happy and peaceful new year .

take care all 

[bluearmy]

48 minutes ago, keithlucky said:

Strat Warming has been forecasted for while,With a complete split of the Polar votex ,we need to see consistency with model output with a zonal reversal with east wind moving from Siberia to UK .

There is no forecast of any ssw and any polar vortex split ?????

there is a consistent forecast of strat warmings surfing the Asian side of the vortex and displacing it towards svaalbard. 

I see a lot of use of the phrase ssw, both here and on SM (severe or sudden strat warming)  - this phrase specifically relates to a warming which causes a reversal of zonal flow at 10hpa/60N.  We are seeing no such forecast from any models.  Runs like the gfs 06z raise interest. 
 

yesterday and today gfs op zonal flow cross section below shows reversal reaching up to around 40/45 N and forcing the zonal flow towards the pole at the top of the strat - of course that could be en route to a proper ssw reversal (displacement or split) 

    

[Snowy L]

While it's a good warm up, it's not affecting the vortex yet. Still intact as one fairly spherical vortex and close to the North Pole

 

Edited December 31, 2022 by Snowy L

[MATTWOLVES 3]

I think its clear too see that at last we have at least a colder clustering of ens from the 6z...much much better than just a few days back.

Right folks obviously we are about to say Goodbye to 2022...so to round up the year I thought I would just put in a few weather extremes that have occurred during this year..if the mods don't mind.

Northern Hemisphere..Highest. shush..Iran..53.6C..August 9th.

Northern Hemisphere lowest....Greenland Summit..-62.4C...31st January.

Southern Hemisphere Highest...Onslow (Australia) 50.7C....13th January.

Southern Hemisphere lowest..Dome fusion (Antarctica)...-81.3C.

And how's about this little stat to finish.

Mt Fuji -30.9C December 23rd.

Hijiori Yamagata 194cm of snow.

302cm of snow in Rokujuri and 410cm at Yudonosan.

Some amazing snowfall totals and some even more amazing temperature contrasts throughout the year. 

Eyes down for 2023.

Edited December 31, 2022 by MATTWOLVES

[Eagle Eye]

Well, I can't not talk about the 06Z GFS can I?

A large thermal wave tilting abnormally transferring heat poleward and really displacing the Strat. It's been the recent trend but nothing anything like this. As long as we can get it centred closer to the Greenland-North American area we're in with a chance of a split with the 'inside job' that I mentioned yesterday or a Wave-2 state transfer with heat pushing into Greenland that's been gathering traction on the ensembles recently.

I'd say that if we can keep a Greenland centring than an upwards Wave-2 flux increase with a high-latitude block (around North America) associated with the lag of MJO phase 7/8 (preferably phase 8 as that build North American high-latitude blocking) then we can get the transfer of upper Trop heat towards the heart of the Strat vortex. 

I've been noting this is probably the way we'd see a quick enough deceleration of the polar-night jet and I'll just quote myself here because I'm lazy...

"see if there's more support from the ensembles for a Wave-2 increase by mid month as that's typically how a PJO (polar-night jet oscillation) influenced SSW happens with a Wave-1 onset before Wave-2 split. Its a lot of hope but the hope does have a little backing at least."

"The initial onset would then have to be followed by a weakening or dipping of Wave-1 amplitude as we see a second thermal wave forming probably around the North Atlantic area. This would be the best chance of a Polar-Night Jet Oscillation (PJO) type of SSW as that would put a cooling Strat vortex on either side of 'outer riding waves' and that thermal gradient cut push through the middle of the vortex and split it in two. I'm definitely not saying that's what's going to happen here but that is exactly how a PJO onset happens and a PJO is almost entirely linked with a major SSW. So if we can get Wave-1 displacement followed by Wave-2 split then that amount of upward wave flux would likely be enough for strong downwards reflection and a quick weakening of the Strat zonal wind downwards. At the moment that's still unlikely but there's a fair number of ensembles taking the Wave-2 amplitude and ramping it up right towards the end of the run. If"

We might slowly be moving towards that solution as Wave-2 increasing is gaining more ensemble support especially towards the end of the run.

Take the 00Z for example

As noted earlier, more Wave-2 ensemble support towards mid January.

And hence the support for a better weakening  going towards February though that may not be enough in itself but its clear that the Vortex remains unstable as shown by the uncorrected forecasts reversal in mid February (light blue line) though the bias corrected forecast doesn't show this (purple line) but it's a good sign for later this Winter if this has been the recent trend. 

Edited December 31, 2022 by Eagle Eye

[JBMWeatherForever]

We haven't had many cold Januarys recently, but the potential for this year to be different is now becoming easier to see, and its the trend that is now clearly our friend !