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Model output discussion - Winter has arrived and the hunt for cold is on

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Nice to see this morning both ECM and GFS keeping the Arctic wedge in play after D10. This will certainly constrain any resurgence of the tPV regrouping so chances of a primed tPV for any wave activity. The bad news (ATM) is even by T312 the GFS ensembles have no Pacific Ridge returning, the mean:

gensnh-21-1-312.thumb.png.535074d82643761c38a057c3c8f9ea6d.png gens-21-0-312.thumb.png.2e06f3928d331cf842b10a452545bc05.png

With the trop vortex over to our NW this should keep the UK in a predominantly PM air mass if the flow doesn't stall. The GFS op goes wedge crazy and we have seen that before, that was downgraded significantly, and maybe another trait of the GFS op (time will tell). As the T312 upper air (^^^) shows, hard to find anything close to a cold UK as we head into the last third of December.

That is all JFF and I suspect the models are still fluid as to what happens after D10 as clearly any amplified pattern will again send cold to mid-lats somewhere in the NH.

From D3-D9 we have a trough over us with the LP cell core around Iceland cycling satellite systems fed early in the run by a NW'ly upper flow so cool and snow flurries chances up north with elevation. Could be worse TBH.

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watch snow-signal for wednesday GFS0z image.thumb.png.7368036416f58d151074ea9e84b9f33a.pngimage.thumb.png.7116d93aa73323734e7505a94173744a.pngimage.thumb.png.18e8a52dc37155512a1015d4ba401b1a.png

Edited by Dennis

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Yes better runs today, still no eye candy though. 🙄

Anyway, just need that mini Arctic high to extend a slither of HP gown into Greenland/Iceland and it would be game on, some runs have already been hinting at this.

 

ICON @T120 

iconnh-0-123.png

iconnh-1-120.png

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1 hour ago, MattStoke said:

I saw heavy snow at 146 m with -2’C 850s last winter.

I wouldn’t mind betting this was in an easterly flow with dry air and low dew point? DP is often as important as upper air. If uppers are -2c and DP is -5c or lower it can usually support snow 

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Scandi High squeezing its way in there?:oldgood:

gfseu-0-132.png

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The snow from Wednesday, the usual suspects, Scottish Highlands mainly:

90-780UK.thumb.gif.6aeb1e237ecf0a31d6269220c4c50444.gif

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8 minutes ago, snowray said:

Scandi High squeezing its way in there?:oldgood:

gfseu-0-132.png

Unfortunately the Russian High delayed exit stage east means that the Arctic wedge is forced toward the Pacific rather than Greenland:

anim_lzo4.gif

So far this season the Russian high has been a thorn in our side and I am currently of the opinion it is a winter waster and lets get rid of especially as it has shown no propensity to get far enough to Scandinavia to be helpful. 

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Anybody else struck by how sluggish/stagnant things become at approx days 8 and 9? I just get a feeling this could be a precursor to a major pattern change. 

Screenshot_20191208-102858.png

Screenshot_20191208-102921.png

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19 minutes ago, IDO said:

Unfortunately the Russian High delayed exit stage east means that the Arctic wedge is forced toward the Pacific rather than Greenland:

anim_lzo4.gif

So far this season the Russian high has been a thorn in our side and I am currently of the opinion it is a winter waster and lets get rid of especially as it has shown no propensity to get far enough to Scandinavia to be helpful. 

Oh dear. And we need that African high over the Med pumping mild air northwards to shove off sharpish too.

gfsnh-0-240.png

gfsnh-1-240.png

Edited by snowray

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8 minutes ago, snowray said:

Oh dear. And we need that African high over the Med pumping mild air northwards to shove off sharpish too.

gfsnh-0-240.png

Yep, the 06z is not worth much more comment, pretty insipid, with cold at a premium, and no precursor to a more wintry Christmas period. Thankfully it will be different again by the 12z!

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Can we get the building blocks in charge for a very cold start to the New Year,it's been a while...

Edited by SLEETY

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6 minutes ago, IDO said:

Yep, the 06z is not worth much more comment, pretty insipid, with cold at a premium, and no precursor to a more wintry Christmas period. Thankfully it will be different again by the 12z!

It might well be different in that it will not look like the 6z - when do 2 runs ever look the same out to 384?  But it will mean the same - will bring the same weather - cannot see it suddenly switching to a screaming Easterly, Never mind looking at after xmas and new year for a pattern change, i can see a scenario where we will be looking at that timeframe to even see any coherent signal in the FI modelling for a pattern change of note.

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8 minutes ago, IDO said:

Yep, the 06z is not worth much more comment, pretty insipid, with cold at a premium, and no precursor to a more wintry Christmas period. Thankfully it will be different again by the 12z!

A nicely located low in the MED but nothing more than that - as you say , it’ll be gone on the 12z.

Lets see if the ENS throw up a trend 

1F81A784-44B6-49F6-B36B-BEF70AD4000F.png

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1 minute ago, feb1991blizzard said:

It might well be different in that it will not look like the 6z - when do 2 runs ever look the same out to 384?  But it will mean the same - will bring the same weather - cannot see it suddenly switching to a screaming Easterly, Never mind looking at after xmas and new year for a pattern change, i can see a scenario where we will be looking at that timeframe to even see any coherent signal in the FI modelling for a pattern change of note.

Yes, agree, no sign of any HL Blocking in the current 16-day window, but the 06z with the Atlantic trough was the worse case scenario. Hopefully we can get something a bit less tepid pre-Christmas? Though as you say, hope casting as the runs are trending less cold with every turn!

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34 minutes ago, IDO said:

Yes, agree, no sign of any HL Blocking in the current 16-day window, but the 06z with the Atlantic trough was the worse case scenario. Hopefully we can get something a bit less tepid pre-Christmas? Though as you say, hope casting as the runs are trending less cold with every turn!

Aye; and all very consistent with both the seasonal models and GP's thoughts. So, stretching into February -- how will the NHP respond to the weakening of the PFJ? Will it give us a snowy Spring, like 1975, or will Europe warm up at a phenomenal rate...Or, none of the above!:unsure2:

h500slp.png    h850t850eu.png

Edited by Ed Stone

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Most charts at 120hrs looking at low pressure sitting in North Sea and bringing cold north to northwest winds.

Snow showers not just in the north.Election day stormy wet snow showers Scotland.Looking unsettled up to Christmas 

and cold snow showers possible anywhere.

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A few better looking FIs in there on the 06z.

12E881DF-74FB-46F6-A600-29B52561D041.png

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2539F13C-2CE1-4B72-AC8C-25A3FDFA8762.png

Edited by Ali1977

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Well the mean has moved up by a degree or so on the 06z by the looks of it, but still some snow symbols there throughout the run, and something colder potentially at the very end.

Ensembles for Birmingham.

graphe_ens3.gif

Edited by snowray

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The GEFS 6z mean longer term is less inclined to build heights from the south compared to the 0z..otherwise it's similar with  a very unsettled outlook and cold enough at times for wintry precipitation, especially across northern hills / mountains..mid month is again most favoured for snow opportunities which are not confined to hills further north!!

Edited by JON SNOW

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21 minutes ago, markw2680 said:

The question I have is why are we all looking into deep fi for changes etc when we all no that small changes early on will completely change the run, very little if any fi actually turn out to be correct. All a complete waste of time if you ask me. Also saying looking towards new year or feb for cold... I mean come on man it’s early December for crying out loud. We may not get lovely northern blocking at all this winter but that doesn’t mean we won’t get cold snaps with snow.

things chop and change hourly let alone in 300 odd hours

It's a good Question however I don't think a 1 day slush fess is going to satisfy the Majority of cold lovers in here.

C.S

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Today's multimodel graphs. Midday temperature trend staying closely the same for most of next week between 7c and 9c.

1055713777_airtemp.thumb.png.74e8fc26e16c776835d598e738944f20.png

The air pressure dropping on Wednesday as the models today grow more confident of a deep area of low pressure on Friday. The trend is still there from yesterday for pressure to rise into next weekend.

pressure.thumb.png.01da025e9106aec1f392a6280afce614.png

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The GFS 12Z operational run most definitely hinting at a more settled spell towards Xmas. It does at this stage appear to be an outlier, personally I would say not as unsettled as conditions next week... A slight dip on those temps as well from the mean towards the big day. A positive sign, or just pie in the sky! I'm favouring a more settled spell away from the NW with perhaps some frosts towards that Xmas period.... Which at least would be more seasonal... Then the chase proper begins for the new year! Euphoric or devastated will be one of the words we feel come the end of this winter... Prozac at the ready... Enjoy the sun if you have it... ☀️🍺😉

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graphe_ens3 (1).png

graphe4_1000_261_77___.png

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3 hours ago, Tim Bland said:

I wouldn’t mind betting this was in an easterly flow with dry air and low dew point? DP is often as important as upper air. If uppers are -2c and DP is -5c or lower it can usually support snow 

It was in a north westerly (polar maritime) flow. Delivered a good few cm of snow, which all melted by morning. 18th January 2019.

Edited by MattStoke

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