Model output discussion - late November

[knocker]

There are some differences regarding the structure and intensity of the vortex lobes that needs to be sorted before high confidence can be placed on the ext mean anomalies this evening, albeit they are in the same ball park  The EPS and NOAA are pretty much in agreement with the main lobe over northern Canada with the GEFs being the odd one out which results in the latter giving more influence to the Atlantic subtropical high and thus the strong westerly flow veering over the UK.

Edited November 27, 2019 by knocker

[Mike Poole]

3 minutes ago, syed2878 said:

Mike  interesting you talk about the Strat according to the Met guys yesterday on Weather studio the zonal wind always has decreased but it will increase again mid month and at the moment they do not see any sign of a SSW

Yes, they do, but not all the models are saying that.  Annoyingly we mortals can't get access to the UKMO models, which we pay for, so we have a narrative about what models we can see, and, as of now, the GEFS have been reasonably bullish about a SSW, and in the 12z, the GFS suggesting, tentatively, it might go for it.  I don't know which is right, we will see...

[Chesil View]

Interesting output this evening. The top three models that go out to 240hrs all have some kind of Greenland or Greeny /arctic combo height rises at that point.

The question now is how much influence can they exert should the models be anywhere close to the actual set up in ten days time.

We shall just have to wait and see.

[StretfordEnd1996]

15 minutes ago, Broadmayne blizzard said:

Interesting output this evening. The top three models that go out to 240hrs all have some kind of Greenland or Greeny /arctic combo height rises at that point.

The question now is how much influence can they exert should the models be anywhere close to the actual set up in ten days time.

We shall just have to wait and see.

Absolutely - and that's a good thing at this stage to see that sort of (loose) agreement at D10

GFS-GEM-ECM

GFS and GEM both drawing down cooler air from the North 

ECM not so much and looks flatter but it's not a million miles away (just slightly east compared to the GFS)

Bit of luck and connecting the dots the HP could lie in a favorable position for colder weather around that time frame

Let's see what happens in the next few days - D10 is a long way off

[tinybill]

24 minutes ago, Broadmayne blizzard said:

Interesting output this evening. The top three models that go out to 240hrs all have some kind of Greenland or Greeny /arctic combo height rises at that point.

The question now is how much influence can they exert should the models be anywhere close to the actual set up in ten days time.

We shall just have to wait and see.

yep  waiting  for the pub run!!

[MATTWOLVES 3]

I have pointed out the last few days how the extended ECM mean falls away again after a mild start... Tonight's mean also highlighting this. The extended mean to nearly mid December is showing a mean of close to - 2 in the Midlands, and closer to - 4C in Scotland. So for me, we can forget about a mild dominated December!! Time to revise your extended forecast again exeter.......

[SMU]

Evening All so after all the ebbs & flows we didnt quite make the cut off high in such a position to send the continental cold over the UK-

Still a good start to December coming up.

Interest in the short term & again post day 8, cold air remaining in situ where its been cold ( relative ) for nearly all of Autumn...

Looking forward to those Frosty nights !

[swfc]

14 minutes ago, Steve Murr said:

Evening All so after all the ebbs & flows we didnt quite make the cut off high in such a position to send the continental cold over the UK-

Still a good start to December coming up.

Interest in the short term & again post day 8, cold air remaining in situ where its been cold ( relative ) for nearly all of Autumn...

Looking forward to those Frosty nights !

Thanks Steve for all the charts and work etc.much appreciated by all 

Edited November 27, 2019 by swfc

[blizzard81]

2 hours ago, swfc said:

I'd agree if it was at 72 hrs but you never know.least we have a drying out period.cant remember last time sun was out and it was dry in sheffield.just has a side note check out GP comments on the strat thread,makes sense

Yep, like you I am looking forward to some nice, crisp dry days - well overdue. Oh! And of course some proper frosty nights. 

[snowray]

God help me, I hate these lows in Winter months when they trend further and further south and then miss us completely. Anyway, lets hope that 18z continues with something akin to the 12z and shifts the HP sharpish, nice to get a few nice crisp seasonal days with frost for now anyway.

[StretfordEnd1996]

Brrr

De-icers at the ready .. (already had to defrost my car a few times this last month or so)

[feb1991blizzard]

Here we go - Arctic high - Atlantic high link up - by 276-288 (ish)

[bluearmy]

The pub run introduces even earlier hemispheric mayhem than the 12z 

[damianslaw]

34 minutes ago, StretfordEnd1996 said:

Brrr

De-icers at the ready .. (already had to defrost my car a few times this last month or so)

By this time of year, high pressure directly overhead in relatively cold air (uppers of -2/-3 degrees will do, doesn't have to be exceptionally cold air) does allow for very rapid cooling at the surface, low lapse rates and very dry air combined with light winds or no wind to stir the air, and with the very weak sunshine, daytime maxima does struggle to nudge much above low single digits and only for 3-4 hours at best (11-3pm), with frost lingering in sheltered parts. Its also the time of year when we can start to embded homegrown cold air at the surface in such conditions, just as we can in the summer with our own heat island, the longer high pressure sticks around without any mixing, the colder the surface air gets.

One of my favourite things to see weatherwise is the sudden freezing over of grass and hard surfaces as the sun begins to set, marking the start of a very cold night, and when it is properly dark, everything glistening in white sparkle. When such conditions occur in December even better, if you can't have snow, then a hard frost will do next. Love that feeling after a walk in the countryside when dusk is setting in and the cold attacks.

I suspect a few sheltered glens will struggle to get above freezing over the weekend. 

 

 

Edited November 27, 2019 by damianslaw

[StretfordEnd1996]

GFS out to +240 very similar to the 12z showing a brief NW'ly incursion around that timeframe bringing again cold uppers into the country

HP actually sets further North over Greenland too

[Ice Day]

2 minutes ago, bluearmy said:

The pub run introduces even earlier hemispheric mayhem than the 12z 

It most certainly does, at 240 we have all sorts of fun and games.  A nice arctic high with ridging up the east side of Greenland with most of the PV away from Canada.  Long way off though and likely to look completely different on the 0z...... nice to look at though!

[StretfordEnd1996]

GFS clutching on a bit of a golden ticket again tonight

Means nothing at the moment though.. need some more ensembles trending into something similar too.

[feb1991blizzard]

A few days after i thought but its coming now - screaming cold uppers rip-roaring through the country with heavy snow showers penetrating well in land.

[CanadaAl]

-8 Uppers over a good swathe of the country by 11 Dec. Of course it's just for fun but it makes for interesting viewing nevertheless

[feb1991blizzard]

Once you get that omnipresent trough pumping WAA up the Western side of Greenland, as long as it doesn't throw any spoilers out into the Atlantic or engage any Scandi troughing, there is only one outcome, very cold with heavy snow showers.

[feb1991blizzard]

That is brutal cold with mins of -15c possible where there is lying snow and clear skies.

[StretfordEnd1996]

Just now, feb1991blizzard said:

That is brutal cold with mins of -15c possible where there is lying snow and clear skies.

I think its a tad early to be posting about specific detail in an event that we don't even know yet exists but hey whatever - its still music to my ears..!

In the nearer timeframe - 

'Seasonable' is the perfect term I'm looking for for this chart

[Mapantz]

2 minutes ago, feb1991blizzard said:

That is brutal cold with mins of -15c possible where there is lying snow and clear skies.

The -15°C you're referring to is across Norway.

[feb1991blizzard]

Just now, Mapantz said:

The -15°C you're referring to is across Norway.

Similar setup here in Dec 2010 and it got down to -20c, look at the trapped uppers under a high, i am only talking IF lying snow and clear skies mind.

[Purga]

Nice reservoir of cold and snow building over the near continent if this pub run is anywhere near the mark!