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Model output discussion - after the beast, what next?


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The UKMO 144 has teased me out if hibernation - for a comment. 144 shows a very meridional flow across 50N with deep cold filtering into Scandi- could be a sharp transition from mild to cold

No mate, I'm still in winter mode as long as the Gfs shows potential arctic blasts..hope it continues!❄❄❄❄❄

Ahhh another chocolate teapot in your post... I believe the last one froze. It seems that we are seeing the second response to the SSW with another surge of negative zonal mean u winds heading fo

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2 minutes ago, winterof79 said:

All up for grabs after Tuesday it seems

image.thumb.png.32b310c83f029b0cce6f46f50741f1e2.png

 

I think this could be described as "To be confirmed" after Tuesday. Rare to see such a bizarre level of scatter...methinks the models are...struggling somewhat post 168 hrs

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1 minute ago, JeffC said:

I think this could be described as "To be confirmed" after Tuesday. Rare to see such a bizarre level of scatter...methinks the models are...struggling somewhat post 168 hrs

I would say the theme for resurgent HLB and MLB will be the front runner for some time to come.

No PV over the dreaded area and a suppressed jet

ECH1-168.GIF?13-12

 

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33 minutes ago, winterof79 said:

An upper Low forecast to head w/sw from Denmark Saturday into Sunday on ECM and GFS

http://en.vedur.is/weather/forecasts/atlantic/#type=prec

180313_0000_120.png

Knocks doing a great job on the short range discussing this.

 

Ive got a feeling the heaviest PPN will be further south than this though and miss us, the EPS mean suggests this as the low heights look a bit shallower, there's still a chance though as a lot of op runs still go for it, either way now I think its nailed on somewhere in the UK will get significant snow as the UKMO now correcting in the Northwards direction and has dropped that hideous shortwave to the West of Ireland.

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4 minutes ago, feb1991blizzard said:

Ive got a feeling the heaviest PPN will be further south than this though and miss us, the EPS mean suggests this as the low heights look a bit shallower, there's still a chance though as a lot of op runs still go for it, either way now I think its nailed on somewhere in the UK will get significant snow as the UKMO now correcting in the Northwards direction and has dropped that hideous shortwave to the West of Ireland.

Yes I should have added that the GFS was further south than this so lets hope the showers bring us what we want.

Then what do I know :)Instability the key once more

http://www.meteociel.fr/modeles/arpege.php?ech=102&mode=1&map=300

Edited by winterof79
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11 minutes ago, TEITS said:

Spot on Nick.

Lets look at it this way. I class a decent spell of cold weather when temps struggle to get above freezing with a decent covering of snow. Now to expect this for just one day in mid March is expecting alot. This to occur for 2-3 days is very rare indeed.

Personally I shall just enjoy whatever arrives this weekend and couldn't careless whether the cold spell extends into next week. I know my Dahlia seedlings won't be happy with this cold spell!

 

Completely agree. 

To be getting these synoptics and depth of cold in mid to late March is exceptional. Solar energy will now be our friend and our foe. It will likely instigate convection further in land but it will also rapidly thaw any exposed lying snow even if temps and dew points are sub zero. John Hammond made a comment on one of his videos yesterday that surprised me actually -  solar energy is apparently now 50% stronger than it was just 2/3 weeks ago at the onset of the last freeze and any deep cold uppers will more quickly get modified by warmer air. 

So a potentially excellent cold snap/spell coming up but unlikely to last long without a further injection of deep cold. Which at this time of year is still excellent. 

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5 minutes ago, East_England_Stormchaser91 said:

Cannot believe that we are seeing another son of the original beast coming straight for us! 

The way things are going, it could well be a spring known for fire and ice style setups. A balmy 15c to potential ice days. Wasn't 1975 a good example of wild swings? 

Spring 1975 was quite cold overall as far as I know, culminating in the snow at the start of June. Then we had a very good summer.

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1 minute ago, abbie123 said:

Well after that cold spell a couple weeks a ago I really thought that was it for cold snowy weather. The beast is back snow showers and cold easterly flow might not last but very impressive for the time of year and we can still get snow in April..

8A9A67B5-2137-4420-8D6F-57CEEB9F54D2.png

6Z not as good though away from the SE, much further South

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2 minutes ago, I remember Atlantic 252 said:

6Z not as good though away from the SE, much further South

We had the exact same situation on the lead up to the last cold spell, and looked what happened. 

Until Thursday earliest we won't know for sure what will happen and even then we won't be looking at snow until Friday early Saturday morning a lot to get through before then 

The GFS is keen to have things further south but the run before was more north of that. The normal backwards and forwards needs to be expected across all models

 

Edited by Surrey
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As always, wouldn’t take the precipitation charts too seriously this far out, particularly given some differences between GFS, EC and UKMO over track of 500mb low moving W or SW over the weekend and how quickly it does so, this upper low will likely be the trigger for more widespread snow showers or longer spells of snow moving west at some point, as it provides steeper lapse rates and large scale ascent.

00z EC quicker with the upper low than 00z/06z GFS, UKMO keeps the upper low over France

For 00z Sunday, 00z EC and 06z GFS

596C5E85-40D2-4011-AE26-F244F94C9256.thumb.png.c5bafa01aa2f07762b1eea75f06a98f0.png10ED2ABD-E354-4BE7-BECD-EEAEE5D54CC5.thumb.png.53e82f3b137ce6e200d9d0d13315f710.png

00z EC has widespread snow showers spreading west across parts of England and Wales Saturday night as the upper low moves through earlier and is across the SW by 00z Sun.

D89D7F86-DE73-4099-BB9E-9C76E2CE0C16.thumb.jpeg.db79afcc6837a467757c36801acef39a.jpeg

06z still has the upper low over the Low Countries at 00z Sunday, and doesn’t get the snow showers going inland until the afternoon 

5DE3B09D-95D9-41A0-8DF8-80643C511DD5.thumb.png.e6853de2a34358031aca8a2e70851ec5.png72EBAD24-8201-4BE6-B76A-F37A8A77698C.thumb.png.f89454bcebb551ec1fb5f9ab55854a0a.png

A look at the EPS spreads vs standard deviation for 00z EC high res suggests greater uncertainty surrounding the upper low 00z Sunday

FEFE9AB5-1D7C-4BCF-98F9-196E5AF1EF3A.thumb.png.6eb9313bf789f2534efd41d1c406a7f0.png

 

Edited by Nick F
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Classic example here of how its nonsense to suggest you cant get potent continental feeds late in season, wouldn't take much change to deliver a big dumping of snow for Inland southern areas of the UK in - YES - nearly April.

gfsnh-1-384_xnx4.png

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So it looks almost certain that the "beast" will hit this weekend.

But the unresolved question is - "where"?

The ECM ensembles this morning are split on the microdetail of this.

As a very rough estimate -

30% of runs emphasise the coldest weather for the north (we talking uppers of minus 12 to minus 16) - thought many of these drop the cold slowly south over the following 48 hours

40% have the coldest weather for the southern half

20% have deep cold just for the SE

10% miss altogether to the south

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2 minutes ago, feb1991blizzard said:

Classic example here of how its nonsense to suggest you cant get potent continental feeds late in season, wouldn't take much change to deliver a big dumping of snow for Inland southern areas of the UK in - YES - nearly April.

gfsnh-1-384_xnx4.png

Crazy chart. If you looked at this chart not knowing the date, you would think it's mid winter not almost April! :cold-emoji:

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3 hours ago, bradythemole said:

Slightly stronger signal in EPS this morning for something to perhaps build out west day 10 and beyond? 

Now the clusters are out, they look far more amplified in the extended period that the mean/anomolys as these are skewed by a troughy Atlantic cluster and differing timings 

so, I would now agree that a notable mid Atlantic upper ridge is still a well supported extended period option 

the shorter term eps show that there is probably a 50/50 split around the op and something closer to ukmo 

thereafter, so many variations on a theme that you wouldn’t want to be anything other than vague - ie. staying cold with a continuing chance of wintry precip though more likely rain to lower levels and further south 

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Perbatation 18 on the GFS in the best outcome for nationwide snowfall with a direct hit and very unstable air. All in all the GEFS is a mixed bag with some members having the coldest air just clipping the south.

Screenshot_20180313-112750.png

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35 minutes ago, feb1991blizzard said:

Classic example here of how its nonsense to suggest you cant get potent continental feeds late in season, wouldn't take much change to deliver a big dumping of snow for Inland southern areas of the UK in - YES - nearly April.

gfsnh-1-384_xnx4.png

The USA is also well below average. A demonstration that you can get cold in North America and the UK at the same time!

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