The hunt for cold - Model discussion (late November)

[Nick F]

25 minutes ago, booferking said:

Thats interesting update as @Catacol  was going for a strong MJO wave and blocking highlighted below for mid month onwards.

Key to this will be the MJO. We continue to see forecasts of a strong MJO wave and without doubt the signal for blocking to return under a Nino base state will return:

We'll have to wait and see, I would have thought the models would start to show blocking before mid-month if it were a strong MJO wave, even given the lag of around 10 days, mid-month onwards I would expect the effect of the MJO 'colder' phases to start to wear off if it had decent amplitude, given it's expected to move to 3/4 fairly quickly. Would like to be wrong and until the start of the week I was hopeful of blocking 2nd week of Dec, but I see the strong jet stream driving the show for the foreseeable, but enough waves / eddies developing at times to allow some transient cold shots and northern snow. 

Edited November 30, 2018 by Nick F

[bluearmy]

The jet should be weakening post day 10 as the Canadian vortex tends nw and the temp gradient becomes less steep as it drifts 

There will still be a nose of low heights into the nw Atlantic - given the Siberian blocking in place, this is why I feel a scandi ridge is far more likely than  a greeny

 

 

[booferking]

22 minutes ago, Nick F said:

We'll have to wait and see, I would have thought the models would start to show blocking before mid-month if it were a strong MJO wave, even given the lag of around 10 days, mid-month onwards I would expect the effect of the MJO 'colder' phases to start to wear off if it had decent amplitude, given it's expected to move to 3/4 fairly quickly. Would like to be wrong and until the start of the week I was hopeful of blocking 2nd week of Dec, but I see the strong jet stream driving the show for the foreseeable, but enough waves / eddies developing at times to allow some transient cold shots and northern snow. 

Thanks for reply @Nick F much appreciated the last set of model runs weren't all dead on blocking so maybe we might see the signal for blocking  grow in the coming days.

Edited November 30, 2018 by booferking

[Mucka]

Yes it is looking as though those who called zonal will be proved correct.

It is actually quite a turn around from the signal we were seeing earlier in the week although it could be argued those were always in FI.

The MetO were also caught out by this as well, forecasting only a small chance of unsettled weather (mobile) and even if it happened it would soon become drier and more settled (blocked)

We can only hope their  forecast for second half of December falls just as flat.

So it is the white flag from me with only the Euros offering some possible crumbs of comfort in FI with the faint hope of getting some wintriness mixed in with the more mobile pattern also looking a no go.

On a positive note we are now pretty much starting from scratch in the next search for blocking and cold so the expected zonal charts won't be so depressing.

The darkest hour comes just before dawn so here is to hoping those scraps on the table in ECM FI keep us going until we get back on the trail of our prey.

Edited November 30, 2018 by Mucka

[tight isobar]

Partial retro- then a wrap off towards scandi!!..

As wave 1's impact begin pv displacement!!- aiding the the syphon-of height placement!?

As the mother lobe begins elongation and westwards progress...in doing so.

So scandi height format...as BA- And others have flagged...big possibilty.

So snaps (posted)...are imo a very feasible evolution..and accomplishment!!..

Great too see how this all evolves...as we enter the new month!!!!

 

gens-0-1-360.webp

gens-0-0-384.webp

gens-0-1-312 (1).webp

Edited November 30, 2018 by tight isobar

[northwestsnow]

29 minutes ago, bluearmy said:

The jet should be weakening post day 10 as the Canadian vortex tends nw and the temp gradient becomes less steep as it drifts 

There will still be a nose of low heights into the nw Atlantic - given the Siberian blocking in place, this is why I feel a scandi ridge is far more likely than  a greeny

 

 

I'm still hopeful of some kind of blocking high to our NE longer term, a LOT depends on some kind of 'break' in the jet- alluded to by your good self above.

Its that or something along the lines of Exeters latest musings, and i really don't fancy ANY of that!

[northwestsnow]

UKMO/GFS very similar at 144- both look pretty ugly but its 168 onwards that holds interest for me .

[shaky]

5 minutes ago, northwestsnow said:

UKMO/GFS very similar at 144- both look pretty ugly but its 168 onwards that holds interest for me .

We have been saying that for the last month lool and we get to 168 hours and beyond and nothing has changed!!at this rate we be waiting all winter mate!!

[Mike Poole]

6 minutes ago, northwestsnow said:

UKMO/GFS very similar at 144- both look pretty ugly but its 168 onwards that holds interest for me .

Yes, I think post T180 looks to have some interest for further amplification, here ICON T180:

GEM looking promising at T192:

I think the 12z's may be more positive than the last few suites.

[Nick F]

1 hour ago, booferking said:

Thanks for reply @Nick F much appreciated the last set of model runs weren't all dead on blocking so maybe we might see the signal for blocking  grow in the coming days.

To tell you the truth, it's not always a clear picture how strong the MJO wave is, the RMM plots show low amplitude, the VP200 and other variables combined suggest more amplitude/stronger MJO through 8/1 as below plots show

So I can see why there may be some enthusiasm for blocking to develop given the above plots. However, I would have expected the models to have churned out some stronger hints of blocking in the ensembles and operationals for week 2 of Dec if the MJO wave was strong, EPS clusters and EC weeklies not on it yet. Given the forecast strength of the upper westerlies over the N Pac, NAM and N Atlantic - see little signs other than transient cold shots for now. But worth seeing if the trop PV retreats poleward over Canada, as some models hint at, which may ease up the strength of the jet stream. Certainly there looks like signs of a relaxation of cold over eastern N America by mid-month, which may allow the jet stream to weaken.

[mulzy]

15 minutes ago, Mike Poole said:

Yes, I think post T180 looks to have some interest for further amplification, here ICON T180:

GEM looking promising at T192:

I think the 12z's may be more positive than the last few suites.

Yes, clear amplification signal from day 8 on most of the NWP this evening.  Thank God - even if it gives us a short break from the wet and windy regime.  Sunny days and a touch of frost will do me for now! 

Edited November 30, 2018 by mulzy

[feb1991blizzard]

Here comes the bluearmy march Westward!

[SLEETY]

back to easterly again in fl on gfs.Hopefully this time it’s a start of a trend,though knowing the gfs the next run will have mild SW winds in fl

[Mike Poole]

Much improved GFS too! although takes a little longer here T240, T312:

Builds the Scandi high, and if we're seeing this sort of output, upgrades always possible as we get closer in time.  Good start this evening.

[northwestsnow]

And we end the run with a 1045mb scandy high-

Nice to see but i think most of us realize its going to to take a bit of luck getting there- atmosphere seems pre disposed to NH blocking if we can get the Atlantic to play ball, it did on 12z and the end result is what i want to see in the run up to christmas..

[ICE COLD]

Yes as others have said , this evening 12z’s are better . The GFS only has around a week of zonal and then high pressure takes over until the end . The only annoying part about that run is the PV over Greenland, it stops the high from building further north , but it gets there in the end . A better run from what we’ve been seeing .

Edited November 30, 2018 by ICE COLD

[northwestsnow]

GEM also sniffing around an easterly at day 10 this evening..

[Yarmy]

11 minutes ago, feb1991blizzard said:

Here comes the bluearmy march Westward!

You have to laugh though, as the really cold 850s get shunted eastwards in the first 200 hours or so of the run leaving a diminished cold pool for the Easterly to tap into. Still a lot better to look at than recent efforts.

[carinthian]

7 hours ago, carinthian said:

Morning all. Really excited about the start of the new ski season tomorrow. All piste groomed and ready to go. As every year passes ,I get more excited at the prospect of being in snow and surrounded by beautiful scenery . Right the charts, interesting feature the wave or low development over Southern Britain at 120t. GFS has this passing further north into the North Sea, whereas UK has a more southerly passage , similar position as highlighted below from Winter View chart below. The thought from over here at 120t, much of the UK will be in a Polar Airmass with the track of the low over Southern Britain to move towards the Alps ( hence we have now a snow alert here for next Wednesday) . So there remains some variability in the short range model forecasts but basically all fairly fluid from west to east. Medium term ,picks up high pressure to SW of Ireland with developing longer wave trough over Central Europe. Thereafter, uncertainty remains as to what extend the Atlantic push into Europe, zonal or more meridional . The forecast jet pattern at 300mb seems inconsistent out in medium longer term forecast models but our experts expect more of a wintry theme to development over The British Isles but cannot say whether this will be sustained. All very interesting. Notice the snow spikes increasing over parts of Britain early next week.

C

Another run and the developing Scandinavian Block comes back on the scene again. Each time it brings it a little nearer to a more liable time frame. Maybe it will be dropped again in consequent runs but it is a reappearing theme. You may have noticed in the above post , the forecast of the  important 300mb jet has been all over the place in the period 10- 15 days, varying from full on Atlantic zonal  to being split to pieces as shown on this latest run. No wonder models are all over the place at the moment but something must be stirring to keep showing these charts to flip -AO in a instant. All very interesting. In the short term the wave track still not settled for early next week, UKMO moves its a little further north but could easily take a route into the continent. Our outer perimeter snow model does have some snow on its northern edge for a while, especially over high ground , maybe from the borders to the North Midlands but this will change on a hourly basis. Have a good weekend ,out on the slopes tomorrow!

C

Edited November 30, 2018 by carinthian

[tight isobar]

1 hour ago, tight isobar said:

Partial retro- then a wrap off towards scandi!!..

As wave 1's impact begin pv displacement!!- aiding the the syphon-of height placement!?

As the mother lobe begins elongation and westwards progress...in doing so.

So scandi height format...as BA- And others have flagged...big possibilty.

So snaps (posted)...are imo a very feasible evolution..and accomplishment!!..

Great too see how this all evolves...as we enter the new month!!!!

 

gens-0-1-360.webp

gens-0-0-384.webp

gens-0-1-312 (1).webp

Something 'a custom' to this !!!!

[feb1991blizzard]

2 minutes ago, Yarmy said:

You have to laugh though, as the really cold 850s get shunted eastwards in the first 200 hours or so of the run leaving a diminished cold pool for the Easterly to tap into. Still a lot better to look at than recent efforts.

Thats a very big cold pool already though!!!    -   The PPN might not be great as the mid level lapse rates could do with being steeper but dont forget - SST's are higher.

[snowray]

3 minutes ago, northwestsnow said:

GEM also sniffing around an easterly at day 10 this evening..

Yup, its the classic case of HP getting sucked up and it all starts off around T180/T192 so thats the timeframe worth keeping an eye on. Looking good I must say, can the hp get a bit further north?

[johnholmes]

2 hours ago, Paul said:

The Netweather winter forecast is online:

https://www.netweather.tv/weather-forecasts/uk/long-range/seasonal

Discussion thread here:

 

Thank you Ian for a very well prepared forecast. As with any of us on any time scale we have to wait to see how close to the actual But thank you.

[Weathizard]

32 minutes ago, snowray said:

Yup, its the classic case of HP getting sucked up and it all starts off around T180/T192 so thats the timeframe worth keeping an eye on. Looking good I must say, can the hp get a bit further north?

Yeah looks good until it gets into a reliable timeframe and too much energy spills over the top and flattens it, the amount of times the models are overly keen on doing this at day 10 range is ridiculous. Much like the GFS tendencies for zonal, bucket loads of salt required!

[bluearmy]

gfsp on board at day 10 - waiting for ecm to give a full house !

Edited November 30, 2018 by bluearmy