The hunt for cold - Model discussion (late November)

[booferking]

9 minutes ago, northwestsnow said:

EPs suggestive of a strong jet coming out of North America Nick?

Gefs have lower heights in scandi area & eps have higher heights in scandi area plus low in Atlantic looks cut off on the eps also.

Edited November 21, 2018 by booferking

[northwestsnow]

2 minutes ago, booferking said:

Gefs have lower heights in scandi area & eps have higher heights in scandi area plus low in Atlantic looks cut off on the eps also.

Yes, but the Atlantic low tilted all wrong from what i can see, ie energy looks to be in the northern arm..

Enjoying model watching whilst hoping the block can hold on..

[carinthian]

43 minutes ago, carinthian said:

UKMO model again the best position at 144t for a cold scenario. ECM/GFS runs again look to progressive in the longer term. The UKMO continues with a strong ridge from Greenland to Southern Scandinavia which will help to keep the flow into the British Isles with a Easterly component. Glad the high cell is not migrating too far west towards NE Canada as that would open up energy of the Northern arm . Two other observations to note is the expansion and deepening of the colder 850mb temps to the NE of the British Isles and low formation in Southern Europe at 144t. That's my thoughts anyway, will get back later with an update from the team over here.

C

Looks like UKMO extended North Atlantic chart at 168t has an attempt by the Atlantic front into SW Britain. Without any access to the charts out NE its hard to say whether a disruption of the front is going to take place. Certainly much colder upper air will be in place over Northern and Eastern Britain, so possible snow to rain event or reverse. Interesting update from our experts over here soon. Will get back with there thoughts for you lot.

 C

C

[Summer Sun]

UKMO extended is more SE'ly this morning with rain moving into the far west

ECM at the same time is more SW'ly

[northwestsnow]

So, EC has the vast majority of energy going up and over whereas UKMO much more evenly distributed..

[johnholmes]

It may not make happy reading to many in here but the upper air pattern is predicted to become a mobile, well fairly mobile, flow off the Atlantic.

The 500 mb anomaly charts, have been a bit variable lately, but they, all 3, show this pattern, see link below.

http://www.cpc.ncep.noaa.gov/products/predictions/610day/500mb.php

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

They do disagree EC-GFS with NOAA re the upper high that NOAA shows on its 6-10 day mean chart in mid Atlantic. Overall the flow though is shown as off the Atlantic. No signal in the 6-14 day period of any northerly outbreak or anything from the east.

[bluearmy]

Icon was isolated in feb (or March)  and proved to be on the money ......

 think it has its hands full this time although expecting the systems to just power through to our ne may also be wrong .......

[Summer Sun]

The ECM op is most certainly on the mild side this morning from around the 28th when looking at the mean

Similar to last night in that up to the 27th has good agreement beyond this is still up for grabs

[mountain shadow]

22 minutes ago, northwestsnow said:

So, EC has the vast majority of energy going up and over whereas UKMO much more evenly distributed..

The ECM Op, even though it's milder into FI, still has no PV over Greenland and a large Arctic high pressure system. It wouldn't be long before proper cold moved towards us.

[bluearmy]

5 minutes ago, mountain shadow said:

The ECM Op, even though it's milder into FI, still has no PV over Greenland and a large Arctic high pressure system. It wouldn't be long before proper cold moved towards us.

The mean or the op?  I’d say both look pretty grim for any height rise in the Greenland area ..... you might squeeze an Icelandic out of the mean later on 

[mountain shadow]

13 minutes ago, bluearmy said:

The mean or the op?  I’d say both look pretty grim for any height rise in the Greenland area ..... you might squeeze an Icelandic out of the mean later on 

The Op. I guess it's all a matter of opinion, but that looks pretty good for the start of Winter. Large Arctic High, fragmented PV, with good heights over NE Canada about to link with the Arctic High, the PV would then move East into Scandi and give us a decent Northerly. All semantics of course.

Edited November 21, 2018 by mountain shadow

[Purga]

Uncertainty rules is my feeling, despite some rather downbeat Op runs this morning.

Precipitation levels do look to be on the increase for sure.

[stodge]

Morning all

Both GFS OP and UKMO suggest we may squeeze another 24-48 hours of chilly weather out of this spell but it's hard to see how it is extended much beyond this time next week.

The problem is the ridging from the south pushing the LP to the NE seems stronger than the ridging from the north pushing the LP to the SE. GFS OP puts the LP over us or through southern Britain and UKMO might do the same but there's nothing for me showing a clear slide SE into Europe keeping the UK on the cold side of the fence.

Looking at GFS OP, Parallel and Control all bring some form of PV into its usual place above NE Canada though interestingly at the very end of FI both Parallel and Control suggest any Atlantic-driven quasi-zonal flow could be short lived. We often see a milder Atlantic flow at the end of November and into December and with that you can see some very high temperatures under Foehn conditions in N Wales and the Moray Firth. I'm not seeing that this time.

Parallel suggests HP building from the south will eventually displace the jet north and allow HP to set up close to or over the British Isles - a good old fashioned winter inversion, anyone? Control sends the PV energy back west over Canada which could allow for new height rises over Greenland into December which would interest many on here but I think that's a longer shot though the idea of a "cold" anticyclone dropping SE over the British Isles has a lot going for it if snow doesn't float your boat.

We will have to endure 7-10 days of milder Atlantic-driven weather before the next opportunity for amplification comes along.

[karlos1983]

54 minutes ago, northwestsnow said:

So, EC has the vast majority of energy going up and over whereas UKMO much more evenly distributed..

You’ll get the sack if you don’t do some work this morning NWS

[shaky]

7 minutes ago, Purga said:

Uncertainty rules is my feeling, despite some rather downbeat Op runs this morning.

Precipitation levels do look to be on the increase for sure.

Want the operational to join that colder  cluster between the 25th and 27th!!right now its in the milder one!!06z here we go..

[SMU]

Morning just a quick one-

1-2cm of snow last night here & up to west kingsdown

A 22 degree spread at day 12 on the EPS indicates a conflict between the Op/ control & the EPS members

We could be seeing more atlantic motion bringing milder air or the usual bias of pushing the block away east-

50/50 this morning for me but very happy with the November snow last night!

[summer blizzard]

UKMO is a little flatter at day 7 than last night (would have been more like the Euro at day 8 ) however it was clear by day 6 that the ship was sinking. 

Euro is just a more progressive version of the UKMO albeit i wonder if with a 1030mb UK high we might in reality see the low never make it through. 

GFS out to day 6 is actually a lot like the 0z (though approach is at a bit of a worse angle). At day 6 though it develops a strong low near Salvabard which screws things up down the line in terms of Scandi/Icelandic blocking. GEM somewhat shows what happens when this low is much weaker (albeit the weaker the better).

..

As i allude to above i am coming round to the notion that the low may never break through. The Euro and ICON only look like they will get a front through at day 7 because they deepen the Atlantic Low substantially (ICON is also quite far west) so if the low is weaker closer to the time we may simply end with a UK or Euro High and the front fizzling out. 

GFS/GEM show the second solution which is a full disruption albeit we have problems to our north in regards to longevity.

If yesterday was 50/50 i would say that we are now 60/40 against an Atlantic breakthrough.  

[Weathizard]

Nice SW’lies at day 6, least the heating bill won’t be too bad its odd because t96 looked promising but the jet is too strong.

 

Possibly another ridge attempt building but I’m worried the jet will flatten that also until a more zonal pattern becomes established

[shaky]

4 minutes ago, Weathizard said:

Nice SW’lies at day 6, least the heating bill won’t be too bad its odd because t96 looked promising but the jet is too strong.

 

Possibly another ridge attempt building but I’m worried the jet will flatten that also until a more zonal pattern becomes established

And then 2 days later a full.on northerly and cold air flooding south!!completely different to the last run!gfs aint got a clue about whats goin on!!

[summer blizzard]

GFS6z is basically GEM but a day or two faster.

Low blows up near Salvabard, low blows up near UK, low behind our low is slow enough that we get a northerly (but the low by Salvabard will screw us by keeping our low moving east). 

[summer blizzard]

 

4 minutes ago, shaky said:

And then 2 days later a full.on northerly and cold air flooding south!!completely different to the last run!gfs aint got a clue about whats goin on!!

Gotta love the day 8 snow showers across most of the Midlands though..

[booferking]

Got to be honest i would take the GFS Northerly toppler its potent enough for low laying snow it would be a great shame to have all this blocking and not see at least one day snow event for all.

 

 

[Weathizard]

5 minutes ago, shaky said:

And then 2 days later a full.on northerly and cold air flooding south!!completely different to the last run!gfs aint got a clue about whats goin on!!

It’s a transient northerly, fairly common practice when a low moves in during winter months... I agree the models are a bit clueless at the moment but I do think we are converging on a less favourable outcome for cold lovers

[weirpig]

Im probably the odd one out   but i like the GFS 6z run  ok its not great for cold lovers, But plenty of weather going on with the low situated over us  with a brisk wind  maybe even snow showers as the low pushes towards the east bringing down a brief northerly    Whatever the Temperature shows it certainlly wont feel that warm.  Interesting weather.

[mountain shadow]

7 minutes ago, Weathizard said:

It’s a transient northerly, fairly common practice when a low moves in during winter months... I agree the models are a bit clueless at the moment but I do think we are converging on a less favourable outcome for cold lovers

With a continued fragmented polar vortex and decent northerly heights across the northern hemisphere I couldn't disagree with you more. Things are setting up very nicely for Winter proper.