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Model output discussion - 20th Feb onwards

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Out to 240hrs on the GFS and a very good/excellent run for most of the country, however slightly higher 850's would be a bit of a concern for the SE contingent, but that's being churlish really!. The whole of UK and Ireland under -6 to -8 uppers by 114.

gfs-1-114.thumb.png.ca69a13d0ad94a18397a

Followed by an almost nationwide snow event at 138

gfs-2-138.thumb.png.b3c614d7bcf212c1b2a8 

Now just to be clear, I'm not saying this will happen but I am just commenting on what this run has shown!!!  

Tremendous stuff from the GFS, come on ECM, don't let us down! 

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The Biscay Low is a tricky one really!

We have lost the very mild uppers being pulled around it on the 12z because its further south than the 00z, but we do need it to edge in to bring some ppn for potential snowfall.

Rtavn1681.gif

The broadscale pattern looks well established to be honest, and its a very good one for colder conditions, but there will be plenty happening with the details between now and next weekend!

Should be fun!

As of tonight though the GFS shows that even the very south could be looking at snowfall as the Low edges north and east!!

186-574UK.GIF?20-12

 

  

Edited by chris55
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11 minutes ago, bobbydog said:

i think the question should be- 'does this potent cold spell look likely?'

possibly....

More so than at any time this winter.There does not seem to be any silly short waves etc to spoil the set up as it's quite a clean evolution.......so far

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12 minutes ago, terrier said:

Great looking gfs 12z. But we have been here many times before. Think I will wait till at least Tuesday evening runs to see if these are still showing. Remember if it can go wrong for the uk it probably will. Wasn't we all suppose to see snow Thursday Friday last week from the models and look how that turned out. Will remain sceptical for the time been of the output but let's hope this time they are correct. 

That was always borderline Terrier.This looks much more favourable.:)

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GEFS are in two clusters with nine (including control) supporting the OP, but 12 have HP over the UK at T120:

Similar to this: gens-19-1-120.thumb.png.f032a197a474a8a5

By D6 there are 12 that manage to achieve some sort of disrupting trough. So early days but looking good seeing this trend is relatively new.

 

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Well that's a very interesting 12Z run from the GFS, which gets very cold air both ahead and behind a front at T144, affecting most of the country with snow. Can the UK possibly miss out again on what seems a very plausible snow opportunity?

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4 minutes ago, Man With Beard said:

Well that's a very interesting 12Z run from the GFS, which gets very cold air both ahead and behind a front at T144, affecting most of the country with snow. Can the UK possibly miss out again on what seems a very plausible snow opportunity?

Yes I expect so

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9 minutes ago, winterof79 said:

More so than at any time this winter.There does not seem to be any silly short waves etc to spoil the set up as it's quite a clean evolution.......so far

and its only 6 days away. what could possibly go wrong?........

said the captain of the Titanic....

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I remember it was last week's when the models were looking good consistently for about 3 or4 days and then it all went bang!! I really hope the same doesn't happen this time.but as someone pointed to the does seem a cleaner evolution this time!:cold:

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GFS at 120 through to 144 is actually quite unusual. Its not common to see such cold 850s to the east AND west of the UK at the same time. Ultimately the 0c isotherme remains in southern France.

Obviously it helps that we are in February with the thermal lag etc but still unusual to see i would think.

Rtavn1382.gif 

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Although both the GFS and UKMO show pressure finally rising over Greenland both could do with an eastwards correction especially the UKMO. You don't want low pressure to the sw but se otherwise milder air could get pulled into the circulation from the Med.

Frustratingly the pattern is now too amplified upstream! Now we have a block its too far west! Normally we want westwards corrections with most set ups but we need a shift eastwards.

 

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3 minutes ago, bobbydog said:

and its only 6 days away. what could possibly go wrong?........

said the captain of the Titanic....

Very nice GFS but the 12z UKMO does not agree.

At 120 hours it has the Atlantic low further north coming from the west which wouldn't give us a nationwide snow event.

Then at 144 hours the pattern looks too far west to me.

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Having scanned the GFS run, I note the 0c isotherm disappears from the UK at 60hrs and doesn't come back until 312hrs......that's 10½ days if my maths is correct.  Cold cold run.

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Just now, karyo said:

Very nice GFS but the 12z UKMO does not agree.

At 120 hours it has the Atlantic low further north coming from the west which wouldn't give us a nationwide snow event.

Then at 144 hours the pattern looks too far west to me.

Yes very frustrating, the best set up is where the low to the nw is weakened and heads se this then heads into central Europe helping to feed the Euro troughing. The flow then switches quickly to the ne, the UKMO is likely to force a high pressure lobe ne ahead of that low to the sw and push milder air nw. Then you have to hope that pressure can build further se out of Greenland to push the milder air back again. If after a whole winter without proper height rises over Greenland the models now decide to have things too far west then really that would be the final insult.

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The GEFS up from 35% snow chance on the 0z to 40% now for London Friday:  graphe4_1000_306_141___Londres.thumb.gif

Getting there. Still lots of spread from T72 and these highlight the different clusters, but also variations within each cluster.

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This mornings ECM highlights my concerns re low pressure to the sw resulting in mild air heading nw out of the Med around the low circulation.

The key thing is pressure remains low over central Europe, if you get that you get the cold. If not then we end up with a nice  looking block to the nw which delivers zip after T144hrs.

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1 minute ago, nick sussex said:

This mornings ECM highlights my concerns re low pressure to the sw resulting in mild air heading nw out of the Med around the low circulation.

The key thing is pressure remains low over central Europe, if you get that you get the cold. If not then we end up with a nice  looking block to the nw which delivers zip after T144hrs.

And you just know that will be the outcome for the uk would sum this winter up. 

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If you look at the gefs ens at 192hrs there is a marked consistancy there with this trough disruption

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=192

here is the mean for that time

gens-21-1-192.thumb.png.f6596bfdb588789e

and the 500 height anomoly,black hole over greenland,set phasers at freeze phase 8

gens-0-5-192.thumb.png.d9f88b91fd269344c

pretty good giong there.:D

 

Edited by Allseasons-si
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2 minutes ago, terrier said:

And you just know that will be the outcome for the uk would sum this winter up.

True in a season where we've been chasing some decent blocking it would be typical that it doesn't set up in the right position. Anyway we've still got the ECM to come , lets hope its better than this mornings output and certainly not like the UKMO!

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4 minutes ago, nick sussex said:

This mornings ECM highlights my concerns re low pressure to the sw resulting in mild air heading nw out of the Med around the low circulation.

The key thing is pressure remains low over central Europe, if you get that you get the cold. If not then we end up with a nice  looking block to the nw which delivers zip after T144hrs.

Your looking to far out Nick, thats at like days 7-8.

It is a perfectly feasible outcome, though it would make little difference what was showing at that range without some consistency.

In the nearer term we are trending in the right direction for now, but as I said earlier that "biscay" low will will need watching in how the pattern eventually unfolds.

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In terms of polar sourced air this is the boom chart of all winter -

image.thumb.jpg.f390d5529e81c9bd2f9a3844

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3 minutes ago, Steve Murr said:

In terms of polar sourced air this is the boom chart of all winter -

image.thumb.jpg.f390d5529e81c9bd2f9a3844

And by 96 hrs,-8's across the country with a pocket of -9

ECU0-96.GIF.thumb.png.a6acc212976539872e

 

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