Model Output Discussion - cold spell to end Autumn

[bluearmy]

Crewe has some valid points - however, I don't believe that the greeny forcing is a requirement re trop/strat activity as kriss has posted. the development of a lobe of vortex over ne Canada in two weeks is becoming consistent on the extended eps modelling. This will fire up the jet exiting the e seaboard and I believe is likely the basis for the met predicting a more mobile picture from mid dec onwards. Whilst the 00z extended means and anomolys looked to be of little decent wintry interest in two weeks time the 12z is much more undercutty with a seemingly upper wedge of heights around greeny which deflects the jet further south and potentially  brings Atlantic systems on an approach which could well be 'workable' for nw Europe. again, just one suite and will be interesting to see how many clusters are on this page later. 

whilst ec op is less neg AO, the strat charts are still displaced as per continuity.

[ScottishSnowStorm]

The ECM 12z decided to throw us a bit of a wobbler but found this from the 0z and from a cold winter outlook it looks good to me 

Not all winter obv but looks to make a good start 

Edited November 27, 2017 by ScottishSnowStorm

[steveinsussex]

19 minutes ago, Ed Stone said:

If just one severe, snowy blast comes our way, I'll be happy...So come on GFS18Z - give us your best??

pref from 23rd december for around 5 days

 

thanks

[Cheshire Freeze]

6 minutes ago, bluearmy said:

Crewe has some valid points - however, I don't believe that the greeny forcing is a requirement re trop/strat activity as kriss has posted. the development of a lobe of vortex over ne Canada in two weeks is becoming consistent on the extended eps modelling. This will fire up the jet exiting the e seaboard and I believe is likely the basis for the met predicting a more mobile picture from mid dec onwards. Whilst the 00z extended means and anomolys looked to be of little decent wintry interest in two weeks time the 12z is much more undercutty with a seemingly upper wedge of heights around greeny which deflects the jet further south and potentially  brings Atlantic systems on an approach which could well be 'workable' for nw Europe. again, just one suite and will be interesting to see how many clusters are on this page later. 

whilst ec op is less neg AO, the strat charts are still displaced as per continuity.

I like to think I have a valid point or two in me Nick! 

Guess it's one of those scenarios where we wait to see how next week evolves and where we could possibly head thereafter!

[Man With Beard]

2 minutes ago, ScottishSnowStorm said:

The ECM 12z decided to throw us a bit of a wobbler but found this from the 0z and from a cold winter outlook it looks good to me 

Not all winter obv but looks to make a good start 

That is a bizarre chart. Almost all of the whole of the 60 degree north band around the globe well below average!!

[I remember Atlantic 252]

2 minutes ago, ShortWaveHell said:

Welcome  well I can say you’re partly responsible for the name as you brilliantly point to how much a spoiler and a maker they can be , thoroughly enjoy your posts on here ! Very knowledge bunch all round ! 

Very true, especially as he lives no where near us, good on him I say, If I lived that far away, I couldn't give a damn about the UK's weather, keep posting Nick!

[ArHu3]

32 minutes ago, Summer Sun said:

NOAA

PREFERENCE: GFS/ECMWF/UKMET BLEND; CONFIDENCE ABOVE AVE

THE 12Z CANADIAN WAS THE WEAKEST WITH THIS SYSTEM WHILE THE 12Z
NAM BECAME THE STRONGEST FROM WEDNESDAY ONWARD -- THE USUAL NAM
BIAS.  A COMPROMISE OF THE INTERMEDIATE 12Z GFS, 12Z ECMWF, AND
12Z UKMET IS PREFERRED WITH ABOVE AVERAGE CONFIDENCE.


SHORTWAVE STREAKING THROUGH THE NORTHERN TIER TUE-THU
SHORTWAVE STREAKING THROUGH THE NORTHERN TIER MON-WED
MID-LEVEL LOW OVER FL THROUGH TUESDAY

Why do noaa bulletins always  have to look like Roman epitaphs? We have lower case letters for at least 500 years 

[booferking]

If the Northerly fails next week then we may have to settle for a white xmas this is almost a quarantee probably around a 9 out 10 verification strike rate.

[knocker]

Interesting looking at the anomalies this evening. They don't agree in key areas but it does give some understanding to the Det. variations, well to me anyway, and the transition to the upstream pattern change makes the later evolution fascinating.

I'll not bother with too much upstream detail in the 5-10 range because that is not significantly different to last night but as always in this situation the key is intensity/orientation of the ridge/trough axis and as can easily be seen the GEFS and EPS do not agree for starters. Although the positive anomalies south east of Greenland are still in situ the GEFS has a much sharper NW ridge which drags the trough further west and south, thus an upper flow WNW over the UK portending unsettled and cold whereas, as also can be easily seen, the EPS is much flatter thus more susceptible to systems taking a more southerly route into the UK

I'm just wondering whetherthe differences are linked to some quite intense upstream amplification, that is Pacific driven, that is taking place during the transition into, and during, the later period. I can't post the EPS but it's not dissimilar with the Aleutian trough and Alaskan ridge and the vortex lobe and cold trough down the east of North America. This has initiated further amplification downstream also but with absolutely no agreement on the intensity and alignment of this with the GEFS leading the way, with positive anomalies still to the south east of Greenland. So as a general comment still looking at an upper flow anywhere from the NWN or NW and remaining unsettled with temps below average.

[comet]

The Canadian warming that we saw late October early November is still playing its hand and that is why we have this northern blocking and Atlantic ridging that we are seeing in the models. I would not be overly concerned by the ECM run this evening best to wait and see where we stand in the morning. Have a feeling there will be many relieved posters by then.

What does concern me though is what the gfs  strat charts are showing in the longer term with warming at the 1mb level not penetrating into the Vortex but rather skirting around the periphery as if stirring and strengthening  the vortex.

Edited November 27, 2017 by comet

[nick sussex]

In relation to Knockers post talking about the Pacific amplification.

There seems to be two bouts coming up the first is whats causing the initial divergences, as the first one takes place between T144 and T168hrs it sharpens up high pressure over the east USA which in turn sharpens up low pressure in the west Atlantic.

The reason I haven't thrown my toys out of the pram this evening is I can't see the hideous west neg NAO setting up and hanging around because any high pressure lobe should be forced east.

The second bout is what the ECM shows at T240hrs with that digging trough in the eastern USA, now in these situations the amplitude there will dictate our ridge to the nw.

Its always difficult this far out to determine how amplified that will be, the shortwaves messing around in the Atlantic are an issue and until that gets sorted we won't know how quickly a northerly flow could get far enough south.

Amidst all this is the chance that some one could get lucky with a shortwave cutting east and hitting the cold air heading south before the northerly clears south.

So a lot going on but really if the UK can't get something out of this it  will be very disappointing.

 

 

Edited November 27, 2017 by nick sussex

[bluearmy]

5 minutes ago, comet said:

The Canadian warming that we saw late October early November is still playing its hand and that is why we have this northern blocking and Atlantic ridging that we are seeing in the models. I would not be overly concerned by the ECM run this evening best to wait and see where we stand in the morning. Have a feeling there will be many relieved posters by then.

What does concern me though is what the gfs  strat charts are showing in the longer term with warming at the 1mb level not penetrating into the Vortex but rather skirting around the periphery as if stirring and strengthening  the vortex.

As I understand it, the upcoming potential reversal (or weak zonal flow) in the strat is led from the bottom up so will possibly not get to the very top parts of the strat. the Berlin charts have been showing a strong vortex high up re zonal flow but displaced well away from the pole 

[tight isobar]

How good would this be for us...

And well in reliable...

Countrywide heavy snowfall @poland!!!

We really need our at-ridge to play ball in coming suites...

As too/shortwaving...

Back to the 18z.

[comet]

5 minutes ago, bluearmy said:

As I understand it, the upcoming potential reversal (or weak zonal flow) in the strat is led from the bottom up so will possibly not get to the very top parts of the strat. the Berlin charts have been showing a strong vortex high up re zonal flow but displaced well away from the pole 

That's true lets just hope it stays there.

[Hull snow]

14 minutes ago, tight isobar said:

How good would this be for us...

And well in reliable...

Countrywide heavy snowfall @poland!!!

We really need our at-ridge to play ball in coming suites...

As too/shortwaving...

Back to the 18z.

This for the uk ?

[Weathizard]

I see trouble ahead with this run. Looking eerily similar to the ECM at day 6, let's see where this goes. The high does seem to be nudging eastwards run by run

Edited November 27, 2017 by Weathizard

[tight isobar]

Just now, Hull snow said:

This for the uk ?

No my freind...

Unfortunatly not!!

Its poland...

[Daniel*]

 

20 minutes ago, tight isobar said:

How good would this be for us...

And well in reliable...

Countrywide heavy snowfall @poland!!!

We really need our at-ridge to play ball in coming suites...

As too/shortwaving...

Back to the 18z.

 I see there is a risk of more organised snowfall for the SE of England on GFS 18z on Thursday courtesy of a shortwave in nearby continent. 

 

Edited November 27, 2017 by Paul

[V for Very Cold]

eyes down....toys in the pram and remember it’s only a weather model

 

 

 

 

 

 

..... yeah right!! 

Edited November 27, 2017 by V for Very Cold

[tight isobar]

4 minutes ago, Daniel* said:

 

Quite frankly no one gives a damn what Poland gets. I see there is a risk of more organised snowfall for the SE of England on GFS 18z on Thursday courtesy of a shortwave in nearby continent. 

 

Yeah i agree on that possibilty ie that south coast shortwave...thursday.

I was merely suggesting synoptics of envy...-polish- overheads!!!

Edited November 27, 2017 by tight isobar

[northwestsnow]

You have to wonder if the wheels are starting to come off....

There does seem to be a lot of energy where we dont want it...

Hope im not being overly pessimistic..

Edited November 27, 2017 by northwestsnow

[Met4Cast]

4 minutes ago, Daniel* said:

 

Quite frankly no one gives a damn what Poland gets. I see there is a risk of more organised snowfall for the SE of England on GFS 18z on Thursday courtesy of a shortwave in nearby continent. 

 

That looks more wet than snowy to me, there's no hashed lines on that chart or the zoomed in, higher resolution chart

 

Edited November 27, 2017 by Daniel Smith

[frosty ground]

2 minutes ago, northwestsnow said:

You have to wonder if the wheels are starting to come off....

There does seem to be a lot of energy where we dont want it...

Hope im not being overly pessimistic..

Not much difference to me

[tight isobar]

We are quickly evolving into a stagnating hp now/previous runs..

Waa becoming more shallow/weak with each run!...

Again could just be a blip!???

[tight isobar]

Just now, tight isobar said:

We are quickly evolving into a stagnating hp now/previous runs..

Waa becoming more shallow/weak with each run!...

Again could just be a blip!???..

Medium term.