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Model output discussion 13th Feb onwards


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It's not just 1 GFS run. A similar theme has showing on many runs and the ensembles have been looking very wintry for mid month onwards for a while now.

 

True, but the ensembles also show quite some disagreement on just how much of the UK will see a cold plunge, if at all.

 

At the moment, I agree with the fact a cooler NW'erly flow looks increasingly likely from mid-month, however there are a few options that I am seeing looking at today's GFS ensemble charts:

 

  • Cold weather to our East and kept away into Europe courtesy of too much Azores high influence, staying milder by day, colder at night with settled weather over most of the UK - similar to what we might see this week, but a tad cooler.
  • Glancing cold snap over the UK briefly, before getting pushed away by the Azores high leaving us in a bit of a N/S split (cooler and wetter N, drier and milder S). The further NE you are, the more likely of some wintry showers in the cold snap.
  • Cool trough influence returning - probably cool and wet further South, perhaps some wintry stuff over hills and mountains the further North you are.
  • Cold plunge from the North with wintry showers for many with a higher likelihood of snow the further North you are. This is due to a more mid-atlantic positioning of the High that gradually pushes North towards Greenland.

 

The key seems to be what happens to the High pressure around the t+200 mark onwards - most options keep it more flat and pushing towards the UK, not allowing much cold to reach us. However there are some that do have a mid-Atlantic ridge which allows more substantial cold weather to push from the North. So if the High pressure stays West enough, we could see some winter weather just as Spring started to get under-way...how convenient! Posted Image Posted Image

 

Still...a while off yet with too much uncertainty on the most likely outcome. Time to enjoy the Sun before I return to bathing under fluorescent light in the office for another week! Posted Image

Edited by Chris K
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A change to much colder wintry conditions courtesy of stratosphere warming continues to gain momentum and should soon be in range of the ECM model.H500 anomaly charts and ncep 8-15 day charts should soon pick up this change.

 

Eh? I'll believe this when I see it- sounds like the kind of thing I've been hearing all winter. There has been a lot of phantom cold this winter that has apparently 'been just out of range'.

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The relatively warm and dry weather continues in the reliable on the GFS 12z

 

Posted ImagePosted Image

 

The cold has been downgraded from the 6z run at day 10, becoming cooler though but not cold enough for snow.

 

Posted Image

 

UKMO at day 6 has high pressure in charge.

 

Posted Image

 

ECM will be interesting tonight, does it get cooler and unsettled like the GFS, or does it stick with the high pressure?

Edited by Barry95
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UKMO has lots of mild but unfortunately cloudy air piling over the top of the high pressure at 144h. Hard to see where it would turn colder from there. Plenty of dry weather to come for the next 7 days with temperatures fluctuating between average and above average/rather warm.

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Clearly some on here don't want to acknowledge this but the signal for the end of the 10-14 day "false spring" is heaving into view.

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014030912/gfs-0-252.png?12

 

Until then, of course, plenty of settled weather courtesy of three separate HP cells which might help the sunshine worshippers as they would "refresh" the conditions each time so as today's HP cell fades, tomorrow's is waiting; 

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014030912/gfs-0-48.png?12

 

Very pleasant conditions with a nice breeze for southern parts.

 

As this cell fades, there look to be a couple of very calm days which could provide some fog issues before HP3 puts in an appearance next weekend

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014030912/gfs-0-144.png?12

 

As HP3 moves across and away to the SE, HP4 tries to move in but doesn't make it owing to developing LP over the Azores and to the west of Iberia:

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014030912/gfs-0-204.png?12

 

The HP is held out to the west allowing LP to come south and it's game over for the settled conditions though the cold blast doesn't last too long.

 

Right out at the furthest edge of FI there's a signal for a renewed burst of cold air for Canada so we could be looking at a renewed burst of Atlantic conditions to end the month:

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014030912/gfsnh-13-384.png?12

 

GEM at T+204 has similarities with GFS - the developing LP over the Azores is pivotal in holding the HP out to the west and allowing the colder unsettled conditions to encroach from the north;

 

http://modeles.meteociel.fr/modeles/gem/runs/2014030912/gem-0-204.png?12

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Here's my general consensus of where things may well develop as we head further into mid to late March.

 

http://forum.netweather.tv/topic/79573-south-westcentral-southern-england-regional-weather-discussion-27214-18z/?p=2943799

 

The above is based around my regional impression and I suspect the much touted UKMO view of a NW-SE split of weather types will continue.

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A change to much colder wintry conditions courtesy of stratosphere warming continues to gain momentum and should soon be in range of the ECM model.H500 anomaly charts and ncep 8-15 day charts should soon pick up this change.

 

I am not sure that your comment about the Stratosphere connection is correct. Mind you the 30mb level chart is not available today and I have not looked recently, maybe someone like chio could give a considered comment? To me any change due to the Stratosphere link should already have occurred.

The MJO shows a 500mb pattern that is unlike what we currently have, phase 8 (upper trough east of the UK and ridge W/NW), so the forecast for this to continue looks a bit suspect and it also  predicted to return almost to the origin. Not a good indicator when it does this I find.

As to the 500mb anomaly charts, EC-GFS and NOAA they certainly show nothing of any cold consequence at the moment so they will have to change pretty quickly to support the current synoptic idea of a colder spell developing.

Of course the synoptic models have once or twice in the past 3-4 years, maybe 4 or 5 times, predicted this change when the anomaly charts have not. However, the odds are way in favour of the anomaly charts getting the pattern change consistently before the synoptic models do.

Of course we shall just have to see if a cold snap, quite possible on the anoamly charts occurs or whether a cold spell, not show yet on them, develops.

 

Neverthe less UK Met have obviously spotted something in their changed longer outlooks.

Edited by johnholmes
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Yes John, The M.E.T have indicated the change to cooler and more unsettled weather last third of month for a few day's now, it's interesting watching the models pick this up, hands up to the GFS for spotting it first! The timing is the difficult bit as usual. .

Edited by Polar Maritime
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Love an "arctic plunge" with -10 to -12 850pha incoming

 

Posted Image

Looking good. Let's hope this verifies. :)

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Looking good. Let's hope this verifies. Posted Image

Absolutely!... The signs have been there for a while now, come on the weather gods give us a little something (cold & snow) that we've been longing for all winter Posted Image

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There is still a fair few ensemble members wanting to bring Colder air in as early as the 15th , I expected them to lessen by now, but if anything signal getting stronger ... Would enjoy the next 5 days as any longer will be a bonus, but needless to say no support for the Warm weather to carry on past 10 days . 

 

Posted Image

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ext ecm still wanting to bring much cooler weather to the UK, with the ens showing below average conditions into days 10-15. Looking at the Op tonight, it would seem this trend is gathering momentum. Yes, higher pressure hanging around for a bit longer, the ens were seemingly too eager to have heights shunted S, and the pressure is now shown to stay high until next week. The week coming will be lovely. But it does look like a week... before I have to get my jacket ready! Winter may have one last bite.

 

Posted Image

GEFS in agreement

Edited by draztik
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Its not a matter of "IF" but "WHEN" the current extremely mild/warm spell comes to an end. After all ,I feel myself that we have had an extended Autumn and today we have skipped Winter and Spring and gone into early SummerPosted Image Posted Image So the change modelled by ecm and gfs  early next week looks fairly likely, but of course as always details will change , March is a very volatile month so expect the unexpected. we have had a remarkable run of mild weather and mother nature will always right itself, so don't discount any Wintry weather even for the south this month, Ecm and Gfs  show "Potential" cold for next week, will this be a very late Wintry spell......We shall seePosted Image

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A whopping 20c 68f today in kent which is very impressive for the 9th March, however, tomorrow will be closer to 15c which in itself is impressive enough but with more cloud around generally tomorrow but during the week ahead the sunshine totals will rocket with temperatures responding and I think some areas could get close to 20c again, by midweek through to next weekend and generally in the 15-18c range but where skies clear overnight it will soon turn chilly.

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ECM ensemble still supporting a return to more unsettled, cooler weather w/c 17th with -5c 850's over all of Scotland by the 18th

 

Posted ImagePosted ImagePosted Image

 

Posted ImagePosted ImagePosted Image

 

But before that we have the first dominant high for 14 weeks a matter of hours away now giving many a dry week with some variable cloud and frosty nights when the cloud breaks

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Tonight's Ecm 12z unlocks the door to the Arctic, a door which has been well and truly locked and bolted all through the winter but perhaps there are growing signs of something wintry on the way once the anticyclone eventually loses it's grip..I hope so.

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post-4783-0-89552300-1394398197_thumb.pn

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Evening all :)

 

ECM brings the breakdown rather sooner than I had expected and I think overplays this slightly.

 

HP3 (see above) never makes it over the country and is held to the SW of the British Isles by the strength of the developing trough over Scandinavia which becomes fully established at T+240 with the transfer of the PV out of Canada.

 

I expect the morning output to strengthen the HP scenario.

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