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Paul

Model output discussion - 16th Nov onwards

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After the breakdown of the cold weekend the ecm run is dominated by the Atlantic culminating in a very nasty looking low which one certainly wouldn't want verified.

 

The GEFS T240 anomaly. Main features HP GOA, cut off low SW US and low N. Canada and Iceland. Weather for the UK zonal and unsettled with a N/S split.

 

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post-12275-0-43897300-1447834172_thumb.p

Edited by knocker

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h850t850eu.png

 

h850t850eu.png

 

h850t850eu.png

 

Azores High. :bad: :bad:

 

At least it will dry off those who affected by flooding.

Edited by pip22

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Another reload??

 

h850t850eu.png

 

h850t850eu.png

 

h850t850eu.png

 

h850t850eu.png

Edited by pip22

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Another reload??

 

 

 

 

 

h850t850eu.png

 

 

 

Looks better from a NH point of view, not a bad looking chart heading towards December..

 

gfsnh-0-222.png?6

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Strongest support to date from the GEFS for the Atlantic to burst through and the jet push through the UK, bringing wet and windy weather after the cold weekend. At D11 the GEFS:

 

post-14819-0-02861700-1447848535_thumb.p  post-14819-0-73867200-1447848601_thumb.g post-14819-0-38259900-1447849370_thumb.g

 

The mean 850s return to nearer average but no sign of the milder conditions returning in the next 16 days. Transient ridging could benefit the south, so a better chance of some drier interludes. The d8-10 for GFS and ECM are on the same long wave ball park for a change. The D15-30 update from the UKMO sticks with a zonal Atlantic theme: Week 3 & 4 of the CFS maintains this setup till mid-December, and that looks a locked in pattern:

 

post-14819-0-22638600-1447848770_thumb.g

 

Of course this weekends shot of cold was unexpected so another 2-3 day mobile cold shot cannot be ruled out, but no clear signal for a pattern change to a longer term cold period. In any case we are seeing rare synoptics so medium term modelling may default to known synoptics so confidence in these models wouldn't be great, though it is the time of year when the growth of the PV can be the main driver. 

 

As for the weekend, snow will be hard to find but it will certainly be cold and with the windchill, very cold; Saturday morning on hi-res model:

 

post-14819-0-18310200-1447849671_thumb.p  post-14819-0-85288200-1447849670_thumb.p

 

Probably colder on Sunday.

Edited by IDO

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h850t850eu.png

 

h850t850eu.png

 

h850t850eu.png

 

Azores High. :bad: :bad:

 

At least it will dry off those who affected by flooding.

 

 

It looks transient though. Doesn't apear to be a "sit and stick" AZH by any means. nothing to worry about I don't think. 

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I'm very happy to see this cold shot but not too excited for snow prospects to low lying parts of England. Looks like a mixture of rain, sleet and hail showers for most though showers around dawn could produce something more wintry and a dusting.

It will start to come into range of the hi res models soon such as Euro4 so we will have a better idea then - hopefully I am being overly pessimistic.

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12z GFS shortens the cold snap this weekend by shifting everything east, but redeems itself later on with a second shot.

 

gfsnh-0-156.png?12

 

Morsels really, but better than nowt.

 

Edit: UKMO looks like it would produce something similar.

 

UN144-21.GIF?18-17

Edited by Yarmy

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12z GFS shortens the cold snap this weekend by shifting everything east, but redeems itself later on with a second shot.

 

gfsnh-0-156.png?12

 

Morsels really, but better than nowt.

 

Edit: UKMO looks like it would produce something similar.

 

UN144-21.GIF?18-17

Pretty worthless though in the end, a few rain showers down exposed coasts. :p

 

Anyway moving on, I think the end of next week will be the next thing to look at. The question is what effect will the developing Pacific ridge have on the UK? I suspect we will see an increasing cyclonic signal as the tropospheric vortex gets pushes towards our side of the pole. The question being how south will the jet drive into Europe and on what axis?

 

This afternoon the GFS brings back the Euro high, whilst the GEM throws a northerly in the 8-10 day range.

gfs-0-240.png?12

 

GEM

gem-0-216.png?12

Edited by Captain shortwave

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h850t850eu.png

h850t850eu.png

 

 

The latest GFS 12Z is still showing a reload end of next week. I guess that is something at least.

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h850t850eu.png

h850t850eu.png

 

 

The latest GFS 12Z is still showing a reload end of next week. I guess that is something at least.

Not a reload really, just a seasonably cold Polar Maritime airmass. :)

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h850t850eu.png

h850t850eu.png

 

 

The latest GFS 12Z is still showing a reload end of next week. I guess that is something at least.

Yep - I'm more interested in that developing LP over Italy; that's a trend I do want to see.

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Hi still looking much much colder this weekend with some snow showers in the north and east of Country but what is interesting is some snow pushing down from the north affecting the Eastern side of country With places like London and south east Could get a surprise â„ï¸â„ï¸â„ï¸â„ï¸ðŸ˜Š

post-21426-0-79442700-1447869043_thumb.j

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Just looking beyond this wekend's cold snap we were monitoring the possibility of a second Arctic shot later next week.

This looks to have been scuppered on this run by the flattening out of the jet upstream over NA.

post-2026-0-12440200-1447868257_thumb.pnpost-2026-0-35722500-1447869691_thumb.gi

 

we can see at t144 another sub-tropical ridge builds into the se of the states which eventually flattens the downstream Atlantic heights somewhat.

There is still enough ridging left  though to give a glancing polar maritime shot but that seems to be the best we can squeeze out of the pattern.

Whilst there is continued wave action on the main vortex,especially over Alaska there may be further oportunities for another release of cold with further upstream ridging.

 

post-2026-0-37261100-1447868633_thumb.pnpost-2026-0-11805500-1447868641_thumb.pn

 

The continued ridging over Alaska is pushing the main vortex towards the Atlantic side which would see the jet wavering around our locale and keeping the polar air quite close to the north of us.

 

 

 

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The extended ens means continue to show a split trop vortex for early December. The spread is so large, however, that there is little confidence to be taken from any output further than a week away. I am a big surprised that Shannon hasn't had an outing in one of Ian's posts. Perhaps this uncertainty too far away currently.

Edited by bluearmy

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Yes it really does look quite potent for the time of year.

To achieve this depth of cold so early in the season is very encouraging.

Worth noting the ECM has been way off on its cold uppers of late and has really only come in to line with gfs this evening.

UKMO pbly called this cold snap best and never flagged it longer than a 48 hour event

Edited by January Snowstorm

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Yes GFS continues to show -9/-11 850s over a large swathe of the UK.

post-12319-0-26567700-1447875661_thumb.p

post-12319-0-19096000-1447875672_thumb.p

Edited by Polar Maritime

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Hmm hate to be the voice of doom but the reality is uppers cold enough to support snow will be across England for only around 24h and at this time of year they are barely cold enough. Quite a different situation to having entrenched cold in place.

 

-10 850's widespread?

Here are the GFS ensembles for Northern England

 

graphe3_1000_258_82___.gif

 

Mean is about -6c and they might just peak very briefly at around -7c (maybe a couple of hours in a favoured region?)

Ground temps are currently projected to be around 4C or 5C

 

Some may see snow falling to low levels if they are lucky but a lot more will likely be disappointed if they believe they are going to see snow falling let alone lying though I wouldn't exclude the possibility if we catch a snow shower in the early hours

Also if we catch heavy shower at the right time in the day it may well turn to snow for a while but most showers will be of rain, hail and sleet IMO.

Edited by Mucka

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Saturday shows a risk of snow across England, even the southeast. This will be an incredible transformation from the 15c temps for most of this week...a lovely wintry bonus. :)

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Edited by Frosty.

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Good Evening All, looking a bit further ahead away from the 2/3 day Artic airmass over the weekend the air becomes modified , but closer to average rather than above and at times below....Gfs makes more of a pronounced Azores high next week , Ecm flattens it and really gives us a blustery west to northwesterly airstream  and even stormy conditions a possibility which models wont pick up this far out :cold:

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