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Whether Idle
20 December 2014 17:12:46

Ive always liked and respected NAVGEM



Dover, 5m asl. Half a mile from the south coast.
David M Porter
20 December 2014 17:31:59


Ive always liked and respected NAVGEM



Originally Posted by: Whether Idle 


The GFS 12Z is rather uninspiring to say the least, but I've come to expect virtually anything from it over the years. I'll only start worrying if & when all the other models start agreeing with it.


Lenzie, Glasgow

"Let us not take ourselves too seriously. None of us has a monopoly on wisdom, and we must always be ready to listen and respect other points of view."- Queen Elizabeth II 1926-2022
Quantum
20 December 2014 17:37:44

Looks very wintry for the 27th, 28th. Blizzard conditions on the hills and widespread snow showers to lower levels.


(Blue = Snow, Green=Rain)



2023/2024 Snow days (approx 850hpa temp):
29/11 (-6), 30/11 (-6), 02/12 (-5), 03/12 (-5), 04/12 (-3), 16/01 (-3), 18/01 (-8), 08/02 (-5)

Total: 8 days with snow/sleet falling.

2022/2023 Snow days (approx 850hpa temp):

18/12 (-1), 06/03 (-6), 08/03 (-8), 09/03 (-6), 10/03 (-8), 11/03 (-5), 14/03 (-6)

Total: 7 days with snow/sleet falling.

2021/2022 Snow days (approx 850hpa temp):

26/11 (-5), 27/11 (-7), 28/11 (-6), 02/12 (-6), 06/01 (-5), 07/01 (-6), 06/02 (-5), 19/02 (-5), 24/02 (-7), 30/03 (-7), 31/03 (-8), 01/04 (-8)
Total: 12 days with snow/sleet falling.
The Beast from the East
20 December 2014 17:43:16

Nice GEM. Not a true GH but holds the ridge for long enough. Thats the best we can hope for now


"We have some alternative facts for you"
Kelly-Ann Conway - special adviser to the President
nsrobins
20 December 2014 17:55:27

GFS shorts in and in the wake of the low on the 27th the mean is now down to -5 and we have the first 30% on the snow risk.
The GFSP in particular is still keen to deliver back-edge snow quite widely next weekend. After that it's pie in the sky as per usual.

The phasing of the upper low and jet streak on the 27th has and will not be resolved for a while yet but my opinion hasn't changed today - potential still exists for a high-end wind event with kitchen sinks thrown in for good measure.


Neil
Fareham, Hampshire 28m ASL (near estuary)
Stormchaser, Member TORRO
Retron
20 December 2014 18:05:27

Snowiest set of GEFS yet down here - 40% on Meteociel, wheras the previous high was 20%. Interestingly London, only 35 miles away or so from here, only has a 30% risk. It's all academic, of course, but it's fun to see anyway.

Looks like a sizeable cluster going for more prolonged cold too - which, coincidentally, matches the EPS.

It would be a very different feel to things on here if the operationals would just flip to the cold cluster!


http://www.meteociel.fr/cartes_obs/gens_display.php?x=306&y=141&run=12&ville=Londres&runpara=0&type=3&ext=1


 


Leysdown, north Kent
nsrobins
20 December 2014 18:09:39

Is the ECM late or is it me?


Perhaps it's flipped so much from it's previous weirdness that it's too embarrassed to appear.


Neil
Fareham, Hampshire 28m ASL (near estuary)
Stormchaser, Member TORRO
Retron
20 December 2014 18:20:22


Is the ECM late or is it me?


Perhaps it's flipped so much from it's previous weirdness that it's too embarrassed to appear.


Originally Posted by: nsrobins 


It's about 20 minutes late by the looks of it - it's now trickling out on WZ.


Leysdown, north Kent
David M Porter
20 December 2014 18:23:02


Is the ECM late or is it me?


Perhaps it's flipped so much from it's previous weirdness that it's too embarrassed to appear.


Originally Posted by: nsrobins 


Maybe there are some technical difficulties just now. The GFS 12z run last night was very late appearing on Wetterzentrale; don't know if the same happened on meteociel et al.


Lenzie, Glasgow

"Let us not take ourselves too seriously. None of us has a monopoly on wisdom, and we must always be ready to listen and respect other points of view."- Queen Elizabeth II 1926-2022
Gooner
20 December 2014 18:41:51

http://www.meteociel.fr/modeles/ecmwf/runs/2014122012/ECH1-168.GIF?20-0


Looks better to me, greens and yellows starting to hit Greenland


Remember anything after T120 is really Just For Fun



Marcus
Banbury
North Oxfordshire
378 feet A S L


Quantum
20 December 2014 18:48:00

That's going to end well, but the strength of the low means there is a mild sector on boxing day and the 27th. I do not envy the people trying to predict these days in particular.


 


2023/2024 Snow days (approx 850hpa temp):
29/11 (-6), 30/11 (-6), 02/12 (-5), 03/12 (-5), 04/12 (-3), 16/01 (-3), 18/01 (-8), 08/02 (-5)

Total: 8 days with snow/sleet falling.

2022/2023 Snow days (approx 850hpa temp):

18/12 (-1), 06/03 (-6), 08/03 (-8), 09/03 (-6), 10/03 (-8), 11/03 (-5), 14/03 (-6)

Total: 7 days with snow/sleet falling.

2021/2022 Snow days (approx 850hpa temp):

26/11 (-5), 27/11 (-7), 28/11 (-6), 02/12 (-6), 06/01 (-5), 07/01 (-6), 06/02 (-5), 19/02 (-5), 24/02 (-7), 30/03 (-7), 31/03 (-8), 01/04 (-8)
Total: 12 days with snow/sleet falling.
Gooner
20 December 2014 18:57:31

http://www.meteociel.fr/modeles/ecmwf/runs/2014122012/ECH1-240.GIF?20-0


I wonder if this will be on the mild side in the ens


Remember anything after T120 is really Just For Fun



Marcus
Banbury
North Oxfordshire
378 feet A S L


Zubzero
20 December 2014 18:58:04

Good end to the ECM but to far out to take much notice off atm


http://www.meteociel.fr/modeles/ecmwf/runs/2014122012/ECH1-240.GIF?20-0


 

GIBBY
20 December 2014 19:03:38

The specifics are not important but the trends are and tonight's trend lead strongly more towards cold and perhaps snow this evening post Christmas. Let's hope it's maintained or expanded upon in future runs.


Martin G
Kilmersdon Radstock Bath Somerset



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Quantum
20 December 2014 19:03:54

Also the 240ecm chart is a perfect illustration of why NAO is more important than AO. Although its difficult to tell from that image whether the AO is negative or positive (being that the 700 is midway between the 500 and 1000 ish), the NAO is certaintly more negative.


If we do get a negative AO though to go along with it, it would certainly increase the stability of the block.


 


2023/2024 Snow days (approx 850hpa temp):
29/11 (-6), 30/11 (-6), 02/12 (-5), 03/12 (-5), 04/12 (-3), 16/01 (-3), 18/01 (-8), 08/02 (-5)

Total: 8 days with snow/sleet falling.

2022/2023 Snow days (approx 850hpa temp):

18/12 (-1), 06/03 (-6), 08/03 (-8), 09/03 (-6), 10/03 (-8), 11/03 (-5), 14/03 (-6)

Total: 7 days with snow/sleet falling.

2021/2022 Snow days (approx 850hpa temp):

26/11 (-5), 27/11 (-7), 28/11 (-6), 02/12 (-6), 06/01 (-5), 07/01 (-6), 06/02 (-5), 19/02 (-5), 24/02 (-7), 30/03 (-7), 31/03 (-8), 01/04 (-8)
Total: 12 days with snow/sleet falling.
David M Porter
20 December 2014 19:07:05

ECM 12z is TOTALLY different to the GFS this evening.


Tomorrow is going to be another day of fascinating model watching I think.


Lenzie, Glasgow

"Let us not take ourselves too seriously. None of us has a monopoly on wisdom, and we must always be ready to listen and respect other points of view."- Queen Elizabeth II 1926-2022
Hippydave
20 December 2014 19:12:14

Interesting individual runs in the GFS Ens - fair old mix of UK hps, zonal, Greenland/Iceland HPs and Mid Atlantic ridging.


Be nice if we got some cold agreement in the ens, although other than some brief milder interludes it's generally looking chilly.


ECM looks nice tonight


 


Home: Tunbridge Wells
Work: Tonbridge
Quantum
20 December 2014 19:15:21

JMA is basically ECM clone though somewhat more wintry.


 


2023/2024 Snow days (approx 850hpa temp):
29/11 (-6), 30/11 (-6), 02/12 (-5), 03/12 (-5), 04/12 (-3), 16/01 (-3), 18/01 (-8), 08/02 (-5)

Total: 8 days with snow/sleet falling.

2022/2023 Snow days (approx 850hpa temp):

18/12 (-1), 06/03 (-6), 08/03 (-8), 09/03 (-6), 10/03 (-8), 11/03 (-5), 14/03 (-6)

Total: 7 days with snow/sleet falling.

2021/2022 Snow days (approx 850hpa temp):

26/11 (-5), 27/11 (-7), 28/11 (-6), 02/12 (-6), 06/01 (-5), 07/01 (-6), 06/02 (-5), 19/02 (-5), 24/02 (-7), 30/03 (-7), 31/03 (-8), 01/04 (-8)
Total: 12 days with snow/sleet falling.
RobN
  • RobN
  • Advanced Member
20 December 2014 19:33:23


ECM 12z is TOTALLY different to the GFS this evening.


Tomorrow is going to be another day of fascinating model watching I think.


Originally Posted by: David M Porter 


Indeed - and none of the GEFS perturbations at 240h to me look remotely like the ECM Op . As you say - interesting times.


Rob
In the flatlands of South Cambridgeshire 15m ASL.
David M Porter
20 December 2014 19:54:21


JMA is basically ECM clone though somewhat more wintry.


 


Originally Posted by: Quantum 


Indeed.


Maybe I'm way off base when I say this, but it seems to me that tonight it's almost a case of the GFS v the other models wrt what happens after Christmas. I'd be more concerned tbh if the GFS was showing the colder scenario unfolding and the ECM went for the milder one.


Lenzie, Glasgow

"Let us not take ourselves too seriously. None of us has a monopoly on wisdom, and we must always be ready to listen and respect other points of view."- Queen Elizabeth II 1926-2022
JACKO4EVER
20 December 2014 20:17:59
Evening all.
Just a quick flick through current data and to be honest I feel this cold snap or spell is being well over played. Alternating periods of cooler and milder weather seem the order of the day to me- a status quo of Decembers fayre so far. 850's are never overly impressive, though to be honest things may be rather decent in Scotland if it's cold snowy weather your looking for. Still lots of good model watching to come over the next few days.
Off for a beer :-)
David M Porter
20 December 2014 20:38:22

Evening all.
Just a quick flick through current data and to be honest I feel this cold snap or spell is being well over played. Alternating periods of cooler and milder weather seem the order of the day to me- a status quo of Decembers fayre so far. 850's are never overly impressive, though to be honest things may be rather decent in Scotland if it's cold snowy weather your looking for. Still lots of good model watching to come over the next few days.
Off for a beer :-)

Originally Posted by: JACKO4EVER 


I think that only time will tell as to whether it is being overplayed or not Jacko, assuming a cold snap/spell comes to fruition. Had this evening's ECM gone down the same road as the GFS. I'd have said that the chances of a cold spell occurring were probably fairly reduced, but it seems to be a fairly realistic possibility at this moment in time IMO.


Lenzie, Glasgow

"Let us not take ourselves too seriously. None of us has a monopoly on wisdom, and we must always be ready to listen and respect other points of view."- Queen Elizabeth II 1926-2022
nsrobins
20 December 2014 20:41:24

http://www.knmi.nl/exp/pluim/Data/PLUIM_06260_NWT.png


ECM suite. There's one run near the end that really has been on the sherry LOL.


Neil
Fareham, Hampshire 28m ASL (near estuary)
Stormchaser, Member TORRO
Stormchaser
20 December 2014 20:41:38

I can still see some potential for a significant storm event even from the ECM version of events, though not as extreme as could occur via the GFS/GFSP route, as the temperature gradient reduces steadily with time and ECM takes a couple of days longer to bring the UK in the firing line for anything running up from the SW.


 


Now how about that U.S. low...


  


The ECM solution (right) has a negative tilt to the trough, and that in combination with the cut-off trough west of the Azores sets us well on course for a cold spell to reach the UK a some point within the following 4 or 5 days.


This is because the energy heads up to NW Greenland and breaks down there, which allows the Greenland block to hang on by shifting SW a bit rather than being blasted apart as happens from the GFS solution (left).


Just how well the blocking holds on comes down to the Atlantic shortwave behaviour; the slower progression on the ECM, GEM and JMA runs places the developing low in the right place to counteract the attempt by the U.S. low to push the ridge out of Greenland.


Having a faster Atlantic low progression is the reason why GFSP, despite having the negatively tilted low at day 5, ends up shoving the ridge out of Greenland and sinking it. At least GFSP was less progressive than GFS, having slowed the storm down from yesterday's runs.


 


In conclusion, now that ECM has started hammering the Euro High south from day 8 onward, it has become clearer that the ECM/JMA/GEM solution is far better for a longer-lived cold spell.


 


I read the U.S. NCEP discussion earlier and it speaks of a negatively tilted trough in 5 days time, suggesting that the GFS and UKMO solutions are being cast aside in favour of the ECM and GEM ones. This is encouraging.


This follows a morning discussion in which it was stated that ECM seemed to have a habit of 'crashing deep lows through obviously blocked patterns'.


Combine the two and you have to wonder if the trough will actually displace the Greenland High at all, after all it doesn't do so on the JMA and GEM runs:


  


...though it's true that JMA (left) is far from clear-cut.


It will be embarrassing for GFS and GFSP if this turns out to be the case... but far from unprecedented in the case of GFS, in fact it could be considered a very typical form of correction for that model.


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Medlock Vale Weather
20 December 2014 20:44:36

Evening all.
Just a quick flick through current data and to be honest I feel this cold snap or spell is being well over played. Alternating periods of cooler and milder weather seem the order of the day to me- a status quo of Decembers fayre so far. 850's are never overly impressive, though to be honest things may be rather decent in Scotland if it's cold snowy weather your looking for. Still lots of good model watching to come over the next few days.
Off for a beer :-)

Originally Posted by: JACKO4EVER 


Not too bad on here but it's worse on netweather  whilst it's understandable that people want some proper snow after last "Winter". I do feel like some people are over analysing charts that are 10 days away the result of which will only end in frustration 80% of the time in our country. I think anything FI is xmas day onwards. 


Alan in Medlock Valley - Oldham's frost hollow. 103 metres above sea level.
What is a frost hollow? http://www.weatheronline.co.uk/reports/wxfacts/Frost-hollow.htm 

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