Model output discussion - Winter has arrived and the hunt for cold is on

[Duane S.]

Quietly happy with the 00z suite. Relatively speaking, decent enough for now.

Small steps to dropping energy into Europe and away from building a solid EU high.

 

[I remember Atlantic 252]

3 hours ago, Big Dave said:

Sorry, what is WAA?   The Q&A page has been closed for some reason.  Thanks in advance.  

hover mouse over it, underlined means it tells you meaning

[Iceaxecrampon]

3 hours ago, jordan smith said:

Ahh Christmas day has now appeared at the end of the Gfs run in FI so let's see what it's showing..

Just in time for Christmas day and the as some call it the "euro slug" (stubborn high pressure sat over mainland Europe) is in full swing! With low pressure to the west being held somewhat at bay drawing up very mild air over the country.. unsettled for the north drier for the south but this is just a snapshot don't take it literally.

I wont.

It's FI.

It's a waste of time.

It will not verify.

Edited December 9, 2019 by Iceaxecrampon

[IDO]

38 minutes ago, Dennis said:

GEM looks promising - High coupling possible Russ/NortPole and Azores/Greenland/Northpole

Yes, that is what we are looking for, but we need the background signals to promote a tropical wave push and from what the experts are saying, the above time frame maybe too early.

The current NH profile is of a HP cell train circulating the lower lats meaning a mobile picture as seen from the run:

Any upstream trough is cut through by the strong jet. The tPV not showing any signs of coupling with a nascent strengthening sPV and the tPV remains up to D10 primed for any wave activity. That is when those wedges become conduits for high-lat blocking. The GFS keeps the Arctic wedge right out into FI;

Many questions; when will the coupling of the PV's happen, will we return to the two UK sector waves (euro/Azores, UK cold killer) and when will the Pacific wave re-establish (will dismantle the Atlantic trough scenario)? I think from past experience waiting for an SSW is a curse on model watching as it raises expectations too much, with still much to understand in that regard.

If we are honest, it looks pretty dire for cold/snow UK wise for the week 2(+) after the bits and pieces we get this week in favoured locations. FWIW CFSv2 forecast at times Europe to be 5c above average in the coming weeks (https://twitter.com/SimonLeeWx/status/1203794488176627717?s=19). Thankfully as others have said, it can flip from warm to cold quickly.

[West is Best]

51 minutes ago, mountain shadow said:

We then need to wait for zonal winds to drop again in February/March for a proper cold spell to develop. 

 

Based on a lifetime of weather watching and 15 yrs on Netweather, this is a faintly ridiculous post. 

[Jordan S]

6 minutes ago, Iceaxecrampon said:

I wont.

It's FI.

It's a waste of time.

It will not verify.

No one said it necessarily would? 

It was a casual look at what it shows nothing more. 

Edited December 9, 2019 by jordan smith

[Anthony Burden]

Both GFS and ECM at ten days out looking to bring pressure rises into Europe,if and its a big if,this occurs 

positioning of the high pressure will be crucial to the second half of December regarding temperatures.

[Purga]

Who invited Uncle Barty for Christmas !

Let's hope the Snow Queen sees him off !

Edited December 9, 2019 by Purga

[mountain shadow]

20 minutes ago, West is Best said:

Based on a lifetime of weather watching and 15 yrs on Netweather, this is a faintly ridiculous post. 

Of course it is.

You've taken one line of what I said and therefore removed the context of being locked into a slug Euro high.

[West is Best]

3 minutes ago, mountain shadow said:

Of course it is.

You've taken one line of what I said and therefore removed the context of being locked into a slug Euro high.

Yes but you've said that we would need the zonal winds to drop. Which is it? The zonal or the blocked Euro high? The two aren't mutually compatible with halting cold over the UK until February March

It's December 9th. 

FI looks tasty on some ensembles. That's the -10C over London.

 

Meantime a lively week of weather with plenty of sleet and snow around.

[Dennis]

ICON 6z see the south track of the Low's - this week increasing.....

[StretfordEnd1996]

GEFS ensembles overnight show the cooling trend this week but beyond D8 things do warm up quite notably for a time. But is there then another cooling trend trying to evolve towards the end of the ensembles? 

Not too many members flirt with the -5 uppers but I still think going into the Christmas period it's not a done deal yet

[johnholmes]

16 minutes ago, West is Best said:

Yes but you've said that we would need the zonal winds to drop. Which is it? The zonal or the blocked Euro high? The two aren't mutually compatible with halting cold over the UK until February March

It's December 9th. 

FI looks tasty on some ensembles. That's the -10C over London.

 

Meantime a lively week of weather with plenty of sleet and snow around.

One only with two that show +10 or so, being a bit choosy are you not?

[Dennis]

the forecast of the NAO seen on the chart.....there could be a turn back to -NAO ?

Edited December 9, 2019 by Dennis

[johnholmes]

The 500 mb anomaly charts, yes I know some of you do not like them. Anyway they show what it says on the tin but they do also show a 'mean' of what the 500 mb contour flow is predicted to be 6-10 days and with NOAA out to 14 days. It is less complex trying to predict how things may turn out on these time scales at 500 mb than at the surface. So what do they suggest?

ECMWF-GFS

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

Much as they both have for a number of days now, some kind of flow from S of West on this morning's charts This is a bit of a change froma week ago when the flow was shown as N of West. The constant is their view that troughing and unsettled is the theme rather than a settled one with any upper high close by.

NOAA is not that different either a week ago or last evening and its 8-14 day chart continues with a flow off the Atlantic , somewhat less strong than the 6-10 charts show, especially in the north. They are of course 'mean' charts so day to day there can be variations but the overall pattern will be similar.

Climate Prediction Center - 6-10 Day 500mb Outlook

WWW.CPC.NCEP.NOAA.GOV

I honestly cannot see any major change in pattern or wavelength for the coming 7-12 days at least. Possibly as the predicted decrease in the flow in the north may allow heights to try and build along with a rise in surface pressure in the longer term, 10-14 days poerhaps? This would mean less in the way of gales in the NW. Temperatures at the surface, with mainly Pm type air then average to below, so some snow on hills from about the Peak District north with a possibility of brief snowfall further south ahead of frontal systems. But no real sign to me of any lasting cold.

Do feel free to tell me different, it is only my attempt at a broad brush treatment using 500 mb predictions.

Edited December 9, 2019 by johnholmes
spelling

[johnholmes]

12 minutes ago, Dennis said:

the forecast of the NAO seen on the chart.....there could be a turn back to -NAO ?

Please remember the NAO is not a predictor, it simply tells how the surface pressure in between north of 60 north and around 40 north is being predicted by the models.

[Chesil View]

1 hour ago, s4lancia said:

Quietly happy with the 00z suite. Relatively speaking, decent enough for now.

Small steps to dropping energy into Europe and away from building a solid EU high.

 

Me too S4L . Although last week's predicted blizzard of the century would have been a nice distraction. I am always very dubious if any cold and snow being predicted before Xmas. Unless absolutely nailed on across the models like 2010. Post Xmas is a different story.Although cross model agreement is (at some point) still a necessity even then.

Edited December 9, 2019 by Broadmayne blizzard

[tight isobar]

Now this is a better profile of alignment...

And the geopotential..

Later in December also offering up some promise..

The Russian noise needs eyeing for possible Scandinavian surge and placement!

6z gfs

00z 500 geo..

@valid 20-December

Edited December 9, 2019 by tight isobar

[Paul_1978]

25 minutes ago, johnholmes said:

Please remember the NAO is not a predictor, it simply tells how the surface pressure in between north of 60 north and around 40 north is being predicted by the models.

Excellent - thanks John. I always wondered which way round it was. Good to know

[Iceaxecrampon]

GFS 06Z

Friday looking very "interesting"

Cabin up - Pennine Blizzards

T+90 is as far as i'm going

#sensible

[feb1991blizzard]

Snow.

[Selliso]

9 minutes ago, Iceaxecrampon said:

GFS 06Z

Friday looking very "interesting"

Cabin up - Pennine Blizzards

T+90 is as far as i'm going

#sensible

Snow level c. 1000ft definitely puts transpennine routes at risk. 

[shaky]

We could be over looking the potential for snow this week!!think some places could receive a surprise come the end of the week!!looking really cold with a biting northwest wind!!

[markw2680]

2 hours ago, mountain shadow said:

I think this is where we're heading unfortunately as the PV winds up and pulls the jet stream back North with Euro heights resulting. 

We then need to wait for zonal winds to drop again in February/March for a proper cold spell to develop. 

Unless a SSW occurs beforehand. 

I have absolutely no words for this.....

the models flip from a mild outlook to a cold outlook and visa versa all the time, who knows in a few days we could be looking at a coming winter wonderland! I’m not saying we will by any means but you just never no.

[snowray]

06z looking pretty decent, LP around Italy has replaced the dreaded African/Euro high, big relief there.

Can the Arctic high build our way I wonder?

Edited December 9, 2019 by snowray