Model Output Discussion - Into November 2019

[Ali1977]

11 minutes ago, Mike Poole said:

GFS T240:

And ghetto strengthening of such an Arctic high is an interesting feature,  still wonder if a passage through via Greenland to ridge to that might happen later on in the run?

A move towards the 06z GEFS blocking , could be a smashed PV in FI 

yup, PV is smashed at t300. What I also like is that we have a very warm Eastern USA and heights heading to Greeny from that to pump the heat into that area . 

USA 850s show this nicely.

Edited November 6, 2019 by Ali1977

[Mike Poole]

10 minutes ago, Ali1977 said:

A move towards the 06z GEFS blocking , could be a smashed PV in FI

Yes, agreed, and this is the positive part of the 12z story (as the focus has so far been on the negative), T300 has that dismembering of the trop vortex, really good to see that view from the ensembles reflected in the op run:

Edited November 6, 2019 by Mike Poole

[IDO]

This is a remarkable NH profile for November with severe cold going well south of our latitude. The setup of Siberian High and Arctic High means little chance of the UK seeing any of that intense cold as we are shut off from the flow.

The US will benefit with dramatic, possibly record breaking November onslaught if the GFS 12z is close:

^^^The 2m temps at 1pm!!! This will be the second cold trough sinking deep south, as the Rossby wave ebbs and flows over the next two weeks.

Thankfully it is only November but unfortunately the NH synoptic has not been our friend for the incoming cold events (as per the norm)!

[swfc]

Has said fi has a good block to the north and PV scattered.on the other hand the deepest area of low pressure in the NH sits over the UK bringing rain and gale force ssw winds!!all subject to change but ironic

Edited November 6, 2019 by swfc

[Jordan S]

1 hour ago, PerfectStorm said:

A period of moderate snow is being forecast by the ICON for northern areas on Saturday as a very slow moving weak front drifts into colder air sitting across the UK. Maybe a couple of cm across hillier areas. 

 

I wouldn't say it's a weak front the Icon and Arpege are showing a pretty active one crossing the UK the northern part of it weakens this is where the snow risk is particularly for higher ground of northern England although for low ground of Scotland.. With the southern side of the rain keeping decent intensity with some bright colours indicating a soggy end to Saturday for cental and southern parts... Quite heavy snow for a time for Scotland shown more so for hills ofcourse but a covering to lower levels looks possible atm. 

Icon.. 

Arpege.. 

Edited November 6, 2019 by jordan smith

[shaky]

15 minutes ago, Mike Poole said:

Yes, agreed, and this is the positive part of the 12z story (as the focus has so far been on the negative), T300 has that dismembering of the trop vortex, really good to see that view from the ensembles reflected in the op run:

I mean what can i say!!am just done cos i know come the time it will flatten out  again just like its done now!!!!it happens every year!!it really is so frustrating!!we get happy with charts that stay at 240 hours plus but come reality its just flat as a pancake!!

[Ali1977]

20 minutes ago, Mike Poole said:

Yes, agreed, and this is the positive part of the 12z story (as the focus has so far been on the negative), T300 has that dismembering of the trop vortex, really good to see that view from the ensembles reflected in the op run:

Let’s hope we start getting some ENS with decent 850s, even with all the blocking not many have gone below -5c!! There always seems to be a huge area of heights around Afghan and North to Russia that shuts off any chance of anything from Siberia !! 

Edited November 6, 2019 by Ali1977

[Mike Poole]

15 minutes ago, shaky said:

I mean what can i say!!am just done cos i know come the time it will flatten out  again just like its done now!!!!it happens every year!!it really is so frustrating!!we get happy with charts that stay at 240 hours plus but come reality its just flat as a pancake!!

Yes, but in the meantime the run ends here, which is one of the most improbable NH profiles I have seen for quite some time!

And further good news, the GEM pretty much goes against everything at T228:

So much uncertainty at so many timescales....

Edited November 6, 2019 by Mike Poole

[Iceaxecrampon]

12z 

What an  upgrade for coldies for the weekend and beyond. Getting towards the reliable. 

Even sleet now at low levels  Heavier ppn now down to 600ft asl

[Methuselah]

An interesting end to the GFS 12Z...it doesn't look all that different to what it was like, back in May: a coldish trough just to our west and an ocean of warm air still stuck to the south and southeast, and a very kinky PFJ... And, still there's a -NAO!

   

Who knows what's going on? Could it have something to do with the current Solar Minimum

[northwestsnow]

5 minutes ago, Iceaxecrampon said:

12z 

What an  upgrade for coldies for the weekend and beyond. Getting towards the reliable. 

Even sleet now at low levels  Heavier ppn now down to 600ft asl

BBC raw suggesting an hour of sleet at 300m asl near my house.

I would urge caution for anyone expecting snow below 350m at a rough guess but would be happy to proved wrong...

Edited November 6, 2019 by northwestsnow

[Mike Poole]

12z GEFS T300:

Absolute continuity of the dismembered vortex theme, I'm struck particularly by the number that has high heights directly over the pole.  The trop vortex is in a mess, so while the prospects of an immediate SSW seem to have receded slightly today, so has coupling of the strat and trop vortices, so as you were with mid term prospects...

Edited November 6, 2019 by Mike Poole

[Mike Poole]

Interesting, so far looks like ECM is following the GEM rather than the other two, T96 ECM first:

Edit, UKMO same time for comparison, 

 

Edited November 6, 2019 by Mike Poole

[Snowyowl9]

Looking pretty cold this month sustained.?

 

[Ali1977]

ECM looks much better at 192, although it’s really just a slight diff it heights over Greeny, but all important WAA splitting the PV

Edited November 6, 2019 by Ali1977

[SLEETY]

Ecm looking cold,looks like Northerly setting up at the end of the run.

 

Sking season going be starting pretty soon in Scotland too,judging by this run.

[knocker]

Highly anomalous east European ridge into the Arctic on this evening's GEFs, which connects to the Alaskan ridge which is adjacent to a complex vortex with troughs  running south and south east  This amplification ensures a strong westerly upper flow exiting the eastern seaboard which continues to weaken and diverge in the vicinity of the UK courtesy of the aforementioned ridge and a trough running south to North Africa. This scenario thus does slow down or halt zonal movement of systems so although portending still changeable, the detail will be a tad tricky. Temps around average

[Mike Poole]

ECM T240:

Inroads into the Arctic, but different places to the other output,...OK, given the current uncertainty, I can see that...

A good time to take stock as to where we are right now vis-a-vis the upcoming winter, informed by the 12z runs.  

I can see no evidence yet from op runs or ensembles that the trop vortex is becoming coherent/coupling with the strat vortex.  That is a good thing, indeed the main thing, for a coldies point of view.  
Immediate UK cold and snow is unlikely, well you could say that about the first part of any November, Mike!  

The recent potential for some was always pie in the sky, which is why I haven't gone on about it in my posts, preferring to focus on winter proper...
We do need now to get the trop pattern sorted out - if it stays disorganised then it isn't clear that we want a SSW at all, if it ramps up and couples with the strat we definitely do!  Uncertainty is large, and we are heading towards a knife edge tipping point (too many metaphors!)  

The result of that tipping point will become evident from the model output soon, maybe next few days.  
You can't say it isn't interesting....

 

Edited November 6, 2019 by Mike Poole

[carinthian]

8 hours ago, carinthian said:

OK, got a bit of an up date from the team over here. They think the latest GFS run flattens the Atlantic ridge far to quickly at 144t and beyond. Certainly a flow NW to SE into much of NW Europe at this stage. Beyond that period their own model hints at a more sharper Mid Atlantic ridging than being shown by GFS and lesser so by the ECM. Also discussed the demise of the Scandinavian heights previous shown on the shorter to medium term models. They think the forecast models are in a volatile state presently and over the coming days with rapid changes in the atmospheric dynamics likely to occur. So flips in the models more than likely but generally the feeling is for a rather cold and unsettled period for most  , especially in NW Europe/ British Isles. 

Just a bit of a follow on from the above post I sent earlier. The ECM run more akin to the thinking of the team over here and that's for more a sharper Mid -Atlantic Ridge than been currently shown by the last few GFS runs. However, as the atmosphere is going through a very volatile change presently, changes still a foot expected. See what the morning brings.  

C

Edited November 6, 2019 by carinthian

[IDO]

31 minutes ago, SLEETY said:

Ecm looking cold,looks like Northerly setting up at the end of the run.

 

Sking season going be starting pretty soon in Scotland too,judging by this run.

Unfortunately we have the triple whammy of HP in Siberia, HP over the Arctic and trough over the US, so in the mid-term there is no way we will get the sustained cold uppers directed to the UK;

T240: 

The best we can hope for is the washout from the cold exiting the US, that  by the time it reaches our shores is warmed out. 

We need a pattern change, but ECM is aligned to the GFS as far as the bigger picture is concerned, viz; Pacific wave, US trough, Azores High, Siberian High, Arctic High, just the finer details as to the wax and wane of these drivers, any which way seemingly not of much help to our region for cold ATM.

Hopefully the models are not tightening up on this pattern, and instead there are changes, leading to a  better placement of the major players, so the UK can get a bit of the action!

Edited November 6, 2019 by IDO

[Methuselah]

As is often the case, in 'stuck' situations, the GEFS posted ensembles don't say an awful lot, due to their being centred on a single locality -- in this case Leicestershire:

   

   

Consequently, temperature-trends don't appear to be going anywhere in particular...?

[carinthian]

The 500mb flow comparison GFS v ECM at 240t highlights a big difference . The red lines of ECM much more amplified compared to the flatter GFS flow. Could all flip again in the morning !

C

[Mike Poole]

Well I think most would agree that that is a sliced vortex even on a mean chart at 10 days, ECM T240:

Won't give anything cold to the UK in foreseeable, but... bigger picture...NH trop vortex having trouble getting out of the starting gates...ah...bless!

[IDO]

24 minutes ago, carinthian said:

The 500mb flow comparison GFS v ECM at 240t highlights a big difference . The red lines of ECM much more amplified compared to the flatter GFS flow. Could all flip again in the morning !

C

I wish I still had the faith of those D9-D10 ECM op runs that show a pumped up HP compared to their mean! However, those days are long gone and my expectation is there will be a meeting of minds by GFS and ECM tomorrow, where they will meet somewhere in the middle.

Though one day the ECM may surprise me!

[carinthian]

7 minutes ago, Mike Poole said:

Well I think most would agree that that is a sliced vortex even on a mean chart at 10 days, ECM T240:

Won't give anything cold to the UK in foreseeable, but... bigger picture...NH trop vortex having trouble getting out of the starting gates...ah...bless!

Yes , no deep cold there yet @Mike Poole but still a rather impressive 10 day full run of negative 850mb temps for the time of year covering all the British Isles. So I think rather cold would suffice but as we all know a lot can change in 10 days.

C