Model output discussion - Winter approaches

[northwestsnow]

EC det again wanting to bring a Northerly in FI ...

Hopefully some support from the suite but I'm beginning to waver a bit now on any Northerly,EC det finds amplification so readily only to backtrack when shortwave start appearing.

That said, the chase is still on...

 

[bluearmy]

28 minutes ago, Nick F said:

Seems to be some reasonable consistency in the last 3 EC deterministic runs to pull a lobe of the trop PV S and SE towards northern Europe while upper ridge amplifies N over the far NW Atlantic early few days of December - which could trigger an arctic-sourced northerly. But the GFS not hinting at this yet.

GEFS mean in the medium range and yesterday’s  CPC 8 to 14 Day 500mb Outlook points to Canada looking blocked with the TPV displaced over towards Siberia, while energy going into STJ over southern states forming a trough over southeastern US which teleconnects to NW Atlantic ridging. All good ingredients to amplify the flow and allow upper trough to dig deep into Europe. But where the axis of the trough digs is crucial, we don’t want the axis too far west otherwise we are the mild side.

Yes nick, at the moment a northerly or nor’wester  of sorts looks likely around day 9-11.  Thereafter, a pulse of low heights drops se within the upper trough. This would bring the threat of a wintry event around day 12/13.  Of course if the blocking to our east is more solid then the trough may be too far west as you mention.  thereafter, we may see an ebbing mid Atlantic ridge with the lw  trough repeatedly dropping into Europe - ‘high risk = high reward’ ??

[northwestsnow]

Mean is OK..

No Euro high...but not signs of amplification in the Atlantic either...

With no meaningful high pressure across Europe we may see rinse and repeat topplers ?

Could do with some amplifation in the Atlantic ASAP would be nice...

[sheikhy]

Easterly pretty much watered down now this mornining!!give it to the 12z to see if it can make a comeback and upgrade!!short term pain for long term gain?still looking cold and frosty from thursday onwards!!

[Weather vane]

Decent day7/8 position for north atlantic blocking across models. Lets hope we see this continue to develop over next few days....

[BlueHedgehog074]

Morning!

The models certainly continuing to show some cool solutions for chilly weather prospects this morning. ECMWF particularly showing some tasty looking 850 hPa temperatures spilling down towards the UK from the North-West at day 10! Can some of this make it down to 00 hours though? Will there be a lot of walking along the paths that’s a garden one? 

One aspect that appears to be evident is a mild South-Westerly pattern for the UK doesn’t seem to be much a theme in the models this morning. Some of those mean and anomaly charts also show some scope for amplification to occur around the Northern Atlantic sector, which could allow some chilly Polar Maritime, possibly Arctic Maritime, conditions to invade our island. Guess it will depend also where any possible troughing around our area set ups. Ideally to have some of the low heights from it going far enough South or East to draw in colder weather between the North-West and East. But it certainly could be much worse for the cold weather fans than what the charts currently show. 

Thought it additionally might be useful to share this post by @Paul from the Covid thread. It covers details on how the pandemic is affecting some of the models’ behaviour recently:

Original article here: 

The impact of Covid-19 on weather observations used by weather models

WWW.NETWEATHER.TV

---

A look at how the Covid-19 pandemic has reduced some of the different types of weather...

Credit to Nick F for the write up

Edited November 24, 2020 by DiagonalRedLine

[Nick F]

10 minutes ago, bluearmy said:

Yes nick, at the moment a northerly or nor’wester  of sorts looks likely around day 9-11.  Thereafter, a pulse of low heights drops se within the upper trough. This would bring the threat of a wintry event around day 12/13.  Of course if the blocking to our east is more solid then the trough may be too far west as you mention.  thereafter, we may see an ebbing mid Atlantic ridge with the lw  trough repeatedly dropping into Europe - ‘high risk = high reward’ ??

Not very often we get high reward for high risk. 00z EC control shows the dangers of the said trough axis digging south too far west.

It always seems we are chasing carrots at the end of the stick every winter, so many hurdles to overcome, be nice for once these teases in the unreliable time frames come off or something cold and wintry to pop up out of the blue. 

But, we are in a reasonable position as we head into early winter, plenty of blocking showing up and a TPV that's not connected to the SPV while displacing towards Siberia.

At least the EC weeklies don't look too terrible, week 3 doesn't look too shabby.

[That ECM]

Gfs mean at t 384. Strong signal to me where the pv is heading. Still much to fall right but prefer the purple blob(technical term) to be there and not nw of us.  Steady she goes.............

[jules216]

ECMWF is trying to lock me in a dream synoptic. The surface cold is imperative to pull trough now as it would take some crazy SW winds to blow away the surface cold. But jaysus the Shannon entropy is huge,already on Friday some ensembles want to just keep the cold moderated but  main run plus control will hopefully be right. Come on EC the king of the models now verify.

[Anthony Burden]

Lots of different ideas between charts this morning,all look good for a chance of continuing with

the cold theme.But save way forward is fax charts up to 120hrs that shows low pressure off

the southwest of U.K. and Scandinavian high bringing southeast winds off the continent.

Frost and fog on the agenda for 4 to 5 days after that lots of options,hope for a cold one.

[johnholmes]

The anomaly charts show the main issue. Will there be a lowering of heights over Europe and at the same time a lifting of heights out in the Atlantic. This giving a WNW or at times NW upper flow into the UK. For how long would be another question.

To illustrate where the probable outlook 6-10 days ahead is, look at the 3 500 mb anomaly charts. EC-GFS seem to be quite firmly in the suggested flow

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

Both showing good heights around the 40-50 West mark with a subsequent marked troughing east of this block, some difference of how far into eErope this might be, with GFS taking it down almost on the meridian but EC further east. Both show a similar pattern to one another over n America which is the pattern needed for the cold burst of air over and east of the UK.

NOAA in its 6-10 is reluctant to join this at the moment, it has the contours showing a more west to east shape and height rises also along a similar path. Its 8-14 does show some indication of the +ve heights showing more towards what would probably leave to some veering of the 500 flow into the UK. But still some way to go to be showing a very similar pattern to the other two.

http://www.cpc.ncep.noaa.gov//favicon.ico Climate Prediction Center - 8-14 Day 500mb Outlook

WWW.CPC.NCEP.NOAA.GOV

Until NOAA does this then the synoptic outputs are going to chop and change. Another couple of days and we should get a definite 'answer' from NOAA!

[Methuselah]

Morning all... I'm back with my ever-popular look at the morning's GFS 00Z at T+384. I see that the deep purples are growing, away to our NE. Defo better than on Greenland:

    

Where there is despair, let there be hope!

Edited November 24, 2020 by General Cluster

[kold weather]

Decent enough morning runs compared to where we could be and of course the ECM looks good. GEM also has a possible very marginal event for the SE, though it looks about as marginal as you can get frankly.

The GFS is meh compared to some others on its 00z run, though it does fit the ECM 46 day very nicely in terms of predicted pattern and precip anomalies so it may also be onto something unfortunately.

[Jeremy Shockey]

GEFS ensemble 2M temps ( 0z )

 

With a mean 2M temp of about 3.5 c for the period 27 Nov - 7 Dec it will certainly feel very chilly as we start Winter ( without being exceptionally cold )

[Penrith Snow]

Its tempting to raise your eyes and say here we go again at the ECM+240 but I would rather it show a superb  chart like that than a 2,000 mile wide Bartlett!

Chances are that it won't verify but it does keep us in the game as an indication of what could happen.

10 years ago this month ECM brought out repeated fantastic charts at 240 and they all came true  

Andy

[Eagle Eye]

Interesting chart here deep purple are playing right now and it won't be long before we see smoke on the water.

[weirpig]

Possible snow  more so over high ground in wales at  102 of the gfs   

[Methuselah]

I think I'm liking the way the 06Z is heading: even some slizzle at T+384:

    

Edited November 24, 2020 by General Cluster

[weirpig]

In the short term    the 6z  lowers the uppers for the south of England compared to the 0z   certainly will feel chillier then late 

[Tim Bland]

10 minutes ago, General Cluster said:

I think I'm liking the way the 06Z is heading: even some slizzle at T+384:

  

Have you patented ‘Slizzle’ or can we all use it certainly a chance of isolated slizzle on high ground. I’m shocked the Met haven’t issued an extreme slizzle warning and put the army on stand by ! ️

[Tim Bland]

Looks like a step towards the ECM to me. Might take a couple of runs to get there. Or we get a halfway house ...

[TSNWK]

Just now, Tim Bland said:

Looks like a step towards the ECM to me. Might take a couple of runs to get there. Or we get a halfway house ...

That looks a pretty darn chilly chart.. east to south east drawn flow from a cold continent meeting a cold north west flow..  I've seen worse

[Tim Bland]

S S S SNOW !! ️

[SMU]

Morning All > A slight relaxation of the Easterly pattern today in terms of cold uppers projected however the end result of a chilly airmass with frost at nights is still on the cards

Other than that the reamplification is still on the cards day 9/10

06z touting snow in the North & the south 216.

[weirpig]

Not Artic weather from the GFS   but much more akin to winter weather    chilly days  cold nights  with temps around 4-6c  during the day  and frosts at night   not a bad way to herald the start of winter