Model output discussion - late November

[Mucka]

UK under a col at the start of FI proper but struggling to get above freezing with lying snow on this run. Snow piling into Northern Britain, outbreaks of sleet and snow anywhere else., very cold for most.

Edited December 3, 2019 by Mucka

[knocker]

The North Atlantic 300mb wind field and surface analysis for midnight

The ridge is still hanging in there today under some intense pressure so after a frosty and foggy start it should be another reasonable sunny day in most areas. The exception being northern Scotland where it will be breezy with the odd spot of drizzle as the cold front associated with the complex area of low pressure edges in from the west

There will not be a general frost and fog tonight courtesy of patchy cloud but further north the continued encroachment of the cold front will bring persistent rain to N. Ireland and western Scotland by the early hours

The weakening front will continue to track down the country on Wednesday and the spasmodic rain will reach the Midlands by dusk with frequent squally showers following over Scotland in particular, Further to the south another generally sunny and cold day once any fog has lifted.

Over Wednesday night and through Thursday further troughs have tracked into the Atlantic from Canada and one is winging across the Atlantic and the associated frontal system will bring some heavy rain to the north which will move south through the afternoon and evening

The rain clears Friday morning leaving a windy day with showers, albeit it is now not so cold, as the system tracks north east and merges with the trough to the north

By Saturday the next trough in the western Atlantic has undergone rapid cyclogenisis and the frontal system associated with this will bring heavy rain and strong winds to much of the country by evening

Edited December 3, 2019 by knocker

[knocker]

And to continue a while with the gfs. A very windy and showery day on Sunday and then the wind veers briefly northerly as the low continues to move east so perhaps some wintry precipitation in the north

By Tuesday the high cell has become established over southern Greenland and there is quite a complex front running south of this into the UK which could produce some snow along the northern edge but this is much to far away to be concerned about detail at the moment

The gfs goes on to displace the Canadian vortex south and thus plunging Arctic air  down to Louisiana with knock on effects downstream so obviously the GEFs and ecm need to be consulted

Edited December 3, 2019 by knocker

[Mucka]

Another small improvement on GFS ensembles as regards a cold signal but still plenty of scatter in the important phases.

 

The Op was an especially cold run for Northern England with 9 successive days close to freezing

Edited December 3, 2019 by Mucka

[knocker]

The ext GEFS mean anomaly this morning

Alaskan ridge with twin vortex lobes northern Russia and Canada with a strong westerly upper flow across the Atlantic the the European trough and negatively anomalous Europe.

Unsettled with temps a tad below average and usual caveats

 

Edited December 3, 2019 by knocker

[Mucka]

ECM sniffing out the trough disruption this time around at least.

[That ECM]

Ukmo ecm and gfs at t144. Ukmo is the odd one out but until all three agree anything past this is just makes interesting viewing. 

[Mucka]

Pretty good agreement between ECM and GFS out to 192 on the general pattern, it is just that ECM doesn't get the cold uppers across us in initial phase which will change run to run,

[MR EXTREMES]

ecm nice hemispheric picture going forwards tasty.

Edited December 3, 2019 by MR EXTREMES

[carinthian]

9 hours ago, carinthian said:

Something in the atmosphere strange around 240t. GFS,ECM and GEM models show a low development punching well south along the Polar Front. The baroclinic zone not really that intense for its formation but the 300mb jet very acute at this stage, so something thing a foot for these models to be showing the low formation out of the blue. Lets see where it ends up, could be some big snowfall out of this one, possible names on it Spain or France , possibly Southern England. Who knows but a unusual and intriguing set up this one. Maybe , our team over here will have some thoughts when I talk to them in the morning.

 C

Morning all , further to the above post, ECM latest still has the ( unusual low placement ) along the Polar Front at 240t and deepening as it heads towards Northern France. Needs watching this development. Thinking of potential snowfall  for southern England for Mid - December as there will be plenty of deepening cold air on its Northern and Eastern flank to tap in to. GFS has even colder air in formation at this time with the potential for trough / low development with-in the same location. 

C

[knocker]

In fact the ecm is not a million miles from the gfs next week and some snow across the northern edge of the front cannot be ruled out at this stage

It too toys with the strong ridge vortex displacement idea

[Methuselah]

Not a bad-looking GFS 00Z, this morning; once the PFJ sinks (by about Day 6/7?) it then remains suppressed until the very end of the run. I guess uppers could do with being a tad colder, but, hey, -6Cs cannot be sniffed at, this early in the season...?

   

But once again, it must be said, the operational is very-much on the colder end of the ensembles:

   

   

Meanwhile, a very chilly day on the farm awaits. Oooh Aargh!

[bluearmy]

16 minutes ago, carinthian said:

Morning all , further to the above post, ECM latest still has the ( unusual low placement ) along the Polar Front at 240t and deepening as it heads towards Northern France. Needs watching this development. Thinking of potential snowfall  for southern England for Mid - December as there will be plenty of deepening cold air on its Northern and Eastern flank to tap in to. GFS has even colder air in formation at this time with the potential for trough / low development with-in the same location. 

C

the small issue of getting to this point applies though ..........interesting direction of travel, especially with strat support 

 

[carinthian]

4 minutes ago, bluearmy said:

the small issue of getting to this point applies though ..........interesting direction of travel, especially with strat support 

 

Yes, I agree but its noted that this unusual development in still there on this mornings main models runs at 240t in one form or another. GEM run deepens this low the greatest and batters the Portugal coast. As I say one to watch . Will be interesting if still being shown in later runs.

 C

[SMU]

3 minutes ago, carinthian said:

Yes, I agree but its noted that this unusual development in still there on this mornings main models runs at 240t in one form or another. GEM run deepens this low the greatest and batters the Portugal coast. As I say one to watch . Will be interesting if still being shown in later runs.

 C

Yes great location for the jet to be in

on holiday on the ECM at 240

Azores > Lisbon > Spain & up.

Again reference to the 10HPA wind driving the deflection.

UKMO noted for reference being pretty poor today ... > Needs to be on board.

[knocker]

One question is how, or will, the further wave activity effect the srat?

 

[shaky]

29 minutes ago, Steve Murr said:

Yes great location for the jet to be in

on holiday on the ECM at 240

Azores > Lisbon > Spain & up.

Again reference to the 10HPA wind driving the deflection.

UKMO noted for reference being pretty poor today ... > Needs to be on board.

You would.expect ecm and gfs to trump ukmo here but the ukmo has these annoying moments of being right and this might be one of them!although the 168 hour chart wouldnt look to bad i think!!

[bluearmy]

The extended eps continue to eventually plonk the low anomoly to our sw and begins to drive a broad sceuro ridge .....that offers a huge range of outcomes, potentially v wintry in any transition but also possibly pretty mild once we get into week 3. too vague to make any predictions beyond the trough. 

 

Edited December 3, 2019 by bluearmy

[West is Best]

We're heading for General Election chaos at this rate.

Heavy snow Tuesday and Wednesday north of the M4.

 

Good to see ECM has come on board.

Edited December 3, 2019 by West is Best

[northwestsnow]

9 minutes ago, bluearmy said:

The extended eps continue to eventually plonk the low anomoly to our sw and begins to drive a broad sceuro ridge .....that offers a huge range of outcomes, potentially v wintry in any transition but also possibly pretty mild once we get to the end of week 2 

 

Week beginning 9th Dec holds some interest Blue

Cold Election day still looks on..

 

 

[bluearmy]

1 minute ago, northwestsnow said:

Week beginning 9th Dec holds some interest Blue

Cold Election day still looks on..

 

 

Yes NWS, that troughing holds wintry potential but still way from being pinned down re detail ........

[West is Best]

This is going to be chaos if this pans out:

 

 

[Iceaxecrampon]

10 minutes ago, West is Best said:

This is going to be chaos if this pans out:

 

 

*BANK*

One week today -  That's Seven Days.

Oh GFS what could possibly go wrong?

Edited December 3, 2019 by Iceaxecrampon

[I remember Atlantic 252]

11 minutes ago, West is Best said:

This is going to be chaos if this pans out:

 

 

 

No way, that's snow for my location, still far out, but these systems track south as model runs go on, so end up being S of the M4 event

[Summer Sun]

It would be quite amusing of the first snow of the season arrives on General Election day. Seems to be a reoccurring theme at present from the models...