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Model output discussion - 5th December 2016 - Into Winter we go


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ECMWF Monthly goes off-piste versus it's deterministic brother into & particularly beyond Christmas. The +ve GPH/MSLP anomalies out to our NE merely intensify again towards end of month, then show

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Run of the century by a mile that 6z!!! Goodness me. 

Heres the cause. And it's actually a shortwave to the south over NW Iberia that helps us. 

This is stopping the Atlantic heights from veering south, and therefore the easiest route is retrogression. One to watch carefully for during the next runs. 

It is then followed by charts that would rival dare I say it 1987,78/79 and even 62/63!!! 

 

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Edited by East_England_Stormchaser91
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5 minutes ago, bluearmy said:

Welcome Louth - in '87 chats only went to four or five days. Not quite apples and pears !

i am a little troubled by how much one operational gfs can do to this thread. Only one way to go from that run and it isn't upgrades! That solution in detail will never verify - as long as you all realise the next run will be less cold and snowy then we will all get on fine in six hours time! 

Oh I've been watching the charts for too many years now to realise something that severe and that far out won't verify. A bit of wishful thinking perhaps. 

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1 minute ago, Louthweather said:

Oh I've been watching the charts for too many years now to realise something that severe and that far out won't verify. A bit of wishful thinking perhaps. 

Can but hope something like this comes off. I don't think i could handle the downward negativity that would follow.

 

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As Blue mentioned, the next run will be a downgrade from the 6z, how far is the interesting bit. If the op are more ENS follow the 06z beware server - you may crash!! 

I don't think the METO will take that much if any notice of the Op, but the pattern still looks a very cold one all the same.

Edited by Ali1977
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Hi

don't get time to post much these days, but the operational run would be like a 1987 event but for 10 or more days instead of 4 and would probably trump any single event in the 20th or 21st century.

Thankfully it is deep in FI and an outlier because if it did come to pass it would be nothing short of catastrophic for us. Some low lying snow for a couple of days cheers most people up, but I wouldn't be wishing for 06z operational outcome for a single moment.

 

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With the inevitable downgrade coming on the 12z (just how much?) I thought one of these might help this afternoon :D

I'll be happy as Larry if the downward trend in 850s remains from the 7th onwards. Doesn't matter too much if the next op is on the milder side as long as we have the same (or more) clusters supporting a cold and snowy evolution in the 12z ens :)

flak.gif

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We actually have had snow grains falling already up here in parts of the North and North East. Some really interesting local variations produced by a mix of lower level wind flows and regional geomorphology. Its white enough outside to suggest a dusting of snow over here.

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2 minutes ago, bluearmy said:

We are a long way from any 'point of no return' re deep cold although a mid Atlantic ridge and sceuro trough is only a few days  from becoming secure

as far as some of the uppers  we see modelled coming our way - be careful what you wish for: experience of model watching tells us that really deep cold uppers coming west across the continental coast tend to create a shortwave at that juncture that stops the flow (this generally doesn't get picked up until four or five days out). Hence the flow stops before it crossed the North Sea/Baltic. To get any really low uppers needs a strong flow advection  which will not allow a shortwave to form or a fast moving cold pool already in existence  or a very short sea crossing. I would be happy to see -10/-12 at this time of year (to begin with at least). Lower than that risks the shortwave drama coming late on and causing much distress !!

 

 

 

Do you think that's what happened with the Dec 2012 saga?, I remember THAT ECM had support from about 4 consec GFS runs and one had a wave develop in the cold pooling and bought insane snow amounts to the pennines and I was celebrating, but over about 4 runs the two sets of troughing to the NW and NE got nearer and nearer and ultimately engaged to the N of us which was game over, these shortwaves scuppered a situation where we seemingly had so much margin for error and ended of completely folding in about 24 hours.

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