Model output discussion - 21st Jan Onwards

[wishingforsnow]

We seem to be getting closer to 'crunch time' regarding what could happen to the PV and when the 'torpedo' will strike also what will happen after. Will be interesting to see how the models and forecasts will react.

[chris55]

Im thinking an official SSW looks unlikely now, out to mid Feb anyway and by then we are cutting it fine to say the least. My interest re the strat is will the warming happening in the next week or so which displaces and weakens the strat pv have any affect on the trop?

Here is todays strat chart, compared with the one above you can see the face value improvements!

 

 

[Eskimo]

6 minutes ago, chris55 said:

Im thinking an official SSW looks unlikely now,

What's an official Sudden strat warming?

[mountain shadow]

11 minutes ago, PerfectStorm said:

What's an official Sudden strat warming?

A reversal of zonal winds at 30hpa I believe.

[bluearmy]

7 minutes ago, mountain shadow said:

A reversal of zonal winds at 30hpa I believe.

10hpa 60 N

[Banbury]

Lets remember a SSW isnt the be all and end all with regards cold for the UK

[mulzy]

The model output in the short to medium term is still poor for those wanting a sustained period of cold weather.  The London 12z GEFS are pretty unremarkable...

The extended (days 11 to 15) ECM ensemble mean show a a period of renewed zonality with negative height anomalies to the NW of the UK and positive height anomalies over the Mediterranean.  No sign of any torpedo and or any other explosive device to be honest.  However, I do believe things will get better from mid February onwards but we need to realistically set expectations...

Edited January 24, 2016 by mulzy

[Timmytour]

The difference between GFS 12z  T102 and the 18z T96

   v  

 

Very very similar......no sense this run is bring us anything back from the pub

Edited January 24, 2016 by Timmytour

[Man With Beard]

maybe just maybe the chance of a brief NWly on that, but it's fairly flat

[Timmytour]

Then at what is now T138 ...

  v  

A deep low travelling north east out of the US several frames before a shallower one travelled out on the 12z

[Timmytour]

Drop the wrapping from a sweet in Washington DC and it could end up on a breeze that takes it to the heart of Siberia...

[Derbyshire Snow]

Hi again

My take on the run so far. Continuing zonal but meridional at times with some incursions of cold. So much of that cold is trapped up north, if only we could tap in to that. If the flow could become  even more meridional it may  just allow  a stronger block to develop in the atlantic. Unfortunately up to t177  only temporary ridging is showing.

The persistent Azores high is a major player as well. Our polar jet stream is less strong i am noticing mid run. Low pressure leaving US not as deep.Might be interesting end of run. We will see.

Edited January 24, 2016 by Derbyshire Snow

[nick sussex]

The GFS 18hrs run has moved to the ECM solution with the deeper Atlantic low and no PV split.  The northerly toppler now looks unlikely unless the models can find more amplitude upstream.

Even though the outputs are building in an Arctic high and taking the AO back towards negative values the NAO is still positive and the Euro high hasn't finished getting its sun tan so is reluctant to leave the scene.

Until that Euro high is removed and displaced much further west then theres no chance of any deeper cold, the wait goes on and on and on.......................

[Derbyshire Snow]

It looks like being frigid in North East America. The GFS op run looks as though its showing an arctic high pushing down in the wake of the bad storms over there. Just a possibility it might put some sort of blocking in North Atlantic

Edited January 24, 2016 by Derbyshire Snow

[Derbyshire Snow]

That high pressure over Canada originating further north has really tried to link up to the Atlantic high but not quite making it. However we do have an almost  full on meridional flow, and would expect heaps of snow on Northen hills, especially in Scotland.

I would say the run shown some promise but no real signs of sustained cold. My hope at the moment would be keep an eye on the heights west of Greenland and Canada to see if future runs bring these in to play

Edited January 24, 2016 by Derbyshire Snow

[Danielvn]

1 hour ago, wishingforsnow said:

We seem to be getting closer to 'crunch time' regarding what could happen to the PV and when the 'torpedo' will strike also what will happen after. Will be interesting to see how the models and forecasts will react.

I do love how someone just made this torpedo thing up as a bit of a hopecast and suddenly it's a thing that people are waiting for.

[Carl46Wrexham]

Eurotrash High stretching west to the Azores at the end of the run (9th Feb).

 

Goodnight Folks

Edited January 24, 2016 by Carl46Wrexham

[wishingforsnow]

2 minutes ago, Danielvn said:

I do love how someone just made this torpedo thing up as a bit of a hopecast and suddenly it's a thing that people are waiting for.

'Hopecast'?

Evidence of strat warming is in place and gaining traction in the models and whether its effect is a major/minor SSW, or displacement is yet to be seen 

Nothing is off the table yet. Experts maintian that change could be likely on the way from mid February onwards. Until then its zonality but perhaps getting more meridional which is a good sign. A SSW isn't the only option that could come off and bring cold to the UK.

Also a lot could change 2 and a half weeks from now weatherwise - models showing a Euro High in FI timeframe are to still be taken with a pinch of salt despite how 'a Euro high takes ages to shift'

We're only at the 23rd January: if by this time next month the supposed 'change' hasn't materialised and it turns out we will have faced another month of mild wet zonality with no sign of improvement at all then yes this winter will have been an overall disappointment in my books but not yet. I think the models will be interesting for coldies again as we enter February should everything go to plan.

[nick sussex]

This GFS run adds insult to injury by weakening the next strat warming. Generally apart from some brief PM air which is okay if you're on the top of Ben Nevis the outputs are garbage for cold.

Sorry to be so blunt but theres no point spinning this. I've decided now to take a zero tolerance attitude to any outputs unless they can deliver non-marginal snow, frost and several days in which to enjoy any snow.

Given the dire winter so far chasing round a few hours of slush isn't going to cut it.

 

[Derbyshire Snow]

This is tomorrows jet stream forecast over US.  Whats happened to it!!! This is the result i think of what the GFS shows mid term with the heights moving south  over Canada and West Greenland. If only the jet stream did not kick back in again, there is a chance those heights might drop in to the Atlantic and produce a stronger ridge. This would obviously have a knock on affect  as the PV would have to be pushed east and then who knows. Clutching at straws but i believe it is another scenario

Edited January 24, 2016 by Derbyshire Snow

[wishingforsnow]

Not really model related but a possible SSW outcome is still being favoured as a possibility out there http://notrickszone.com/2016/01/24/sudden-stratospheric-warming-may-bring-another-cold-spell-to-western-and-central-europe-in-early-february-models-suggest/#sthash.FVZxu6T0.cGAIm8iE.dpbs

I think we have to wait and see what the situation is early/mid February. By then I think that if a change will be on the way the models will be showing it. 

[Singularity]

@IDO, the CFSv2 long range product is based on reanalysis data and tries to find the right analogues. This year there are no previous cases that are close enough to really qualify, so I'm inclined not to take any notice of CFSv2 for the foreseeable. Just a heads up on that.

. . . . . . .

Anyway, I've decided its time to yammer on about the MJO again.

Notice anything different to recent days? If not, you might wish to contact Specsavers  because the GEFS mean has performed an almighty jump from showing a venture into 2/3 to an 'almost but I'm too shy to go there' phase 4/5. It then gets distracted by the Indian Ocean's warmth again... will it ever learn? Not without human input it won't!

Now then, what to make of the actual observations. Being right toward the 'nowhere' zone there's not much to be said really other than there's a lack of coherent activity at the moment. At times like this it is very difficult for the ensemble products to form a good consensus on exactly when and where the convection will get its act together. 

Currently, ECM is definitely seeing a signal for amplification, but there is total confusion over what to do with the MJO afterward (ECM ens. below left):

  

This really does highlight the effect of that warm Indian Ocean and in truth the likes of myself are for the most part reliant on theoretical science based on past observations in order to make the call for a classic eastward propagation through to phase 5 and beyond. This is one thing that GEFS has suddenly seen the beginnings of, for whatever reason that may be. Interestingly the bias-corrected version (above-middle) just about emerges from the COD during that propagating period and then starts to behave rather like the ECM ensembles. It looks to me that the closeness of the day-to-day points on the means is a result of the wide spread in timings between the ensemble members as opposed to a genuine prediction that the MJO will amplify so very slowly.

Finally I turn to 'old faithful' - the UKMO. For reasons unknown to me, the model continues to call for a faster amplification and initiation of propagation eastward than the other models are indicating. It's very much in line with the theoretical expectations and if it does prove to be right this time around it will be the second win for the model with respect to the initiation and early propagation of an MJO event achieved this season. Intriguingly, such dominance over the other models has not been observed once the MJO has got going, with more of a hybrid between ECM and UKMO tending to be the best guide.

 

The implications of UKMO being at least nearest the mark would be seen from what is currently around a week's range, and be greatest for GEFS/GFS, with a considerable removal of westerly momentum from our latitudes possible. ECM may not change so much in that respect, but the location in which the jet digs south could adjust somewhat. All speculation of course, based on a scenario which while favoured, is far from guaranteed.

Oh and I think its about time I reminded people that GP told us a couple of weeks or so back that, should the tropical forcing act as anticipated, we could get along just fine without a SSW in Feb. I see little reason to depart from that belief at this point in time, though I would like to see the displacement being toward Europe as much as possible to lend a helping hand.

Good night, and May The Forcing Be With Us 

Edited January 24, 2016 by Singularity
T'wit T'woo

[snowangel32]

A nasty pattern developing the last few winters America gets cold and snow wich fires up the atlantic and the UK is a bullseye for the jet stream. The PV looks stronger than ever and until we either see the jet stream dig further south or that limpet over greenland move we are just stuck in a December like pattern. Who ever said When America gets cold and snow the Uk will follow. I am not saying winter is over but looking at the cold heading into america throughout the 18z just cant see any significant change coming. Starts praying for a SSW. 

[Ali1977]

Well, nothing great this morning - models still not out till mid Feb yet though - that sounds like when the chance lies for a poss colder set up according to the Pros, so I'll stick with that.

Edited January 25, 2016 by Ali1977

[terrier]

Well I think a 1000 words say it all this morning with the lack of comments. The gfs is mild throughout with this week looking particularly wet once again. Ukmo and ecm not much better pv looks as strong as ever. I know Steve murr mentioned last week he thought if we didn't see anything soon it could be another abysmal winter. And looking at the output looks like he may just be right.