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DiagonalRedLine

Model Output Discussion - The Run In To Christmas

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I was just going to reply to Frosty saying exactly the same thing! Wider NH synoptics mean zilch if the weather on the ground here isn't benefitted by them!

It's like your wife treating herself to some new sexy lingerie, only to find out they're for the benefit of another fella.

 

Yes this reference to last year is rather unfair. There was lots of mid-latitude cold last year, with the US put in the freezer time after time. We were on the wrong end of it. So yes synoptics are better than last year but who is to say the same wont happen again. The first cold spell went to the US. Looking at the last 8 days of December it looks like the US will get another 2-3 reloads of very cold uppers heading south, whilst on this GFS run we end up in the mild sector again. Even with an SSW we cannot guarantee cold over the UK. I will believe it when I see it. The CET for November was +2c and we are already in a positive CET for December with some mild weather incoming from Sunday, so no sign yet of the cold! 

The control was zonal pretty much throughout the run: post-14819-0-38615300-1418925323_thumb.p

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The irony is if the GFS 12z was correct then this December might actually come out milder than last year  :rofl:

Dear oh dear, we have come to the point now where we could still get a prolonged spell of cold weather, or indeed get nothing (that includes the cooler days which were agreed on for Christmas Eve/day).

How that low in the central Atlantic develops and interacts with the ridging around it will determine when and where it will move. This will take a couple more days to resolve.

It's a mass knee jerk reaction over 1 model run, I'm sure john Holmes is shaking his head in disbelief..I will keep the faith until such time as the MO backtrack but currently the outlook for next week is for a taste of winter, not the bitterly disappointing taste we have got used to in recent years.

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How do you like your Christmas weather? All are catered for within GFS ensembles.

 

gensnh-1-1-174.png?12gensnh-11-1-174.png?12gensnh-12-1-174.png?12

 

Signal for Xmas day Northerly very muted in 12z ensembles.

 

graphe3_1000_255_103___.gif

 

But most importantly a very obvious split developing with 2 distinct clusters milder/colder from day 5.

Which will we get?

 

 

It would be funny if perturbation 1 was correct with HP over europe ridging over england giving us a cold and foggy xmas whilst it was mild and breezy in scotland, with the trend of recent GFS OP's to build stronger HP influence just to our south it's a possibility.

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Not sure I can agree with that. Not once last year did we see any cold frosts in London and already I've seen a few heading off to work early. Much better December in terms of the pattern and moving forward....of course if we are the wrong side may not happen this time but this year we have East qbo, wave 1 an 2 attacking the pv, better Synoptics for at a chance of cold, possible Ssw or at least very weakened vortex allowing chances of hlb into Jan....This year is miles better than last years storm mild fest of a season and it's only 18Th Dec

Yet some of us saw a White Christmas last year :)

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To be honest and we're all guilty of it we get hung up over a t264 chart and tend to run with it. Think if we just stuck to the reliable timeframe of t96 possibly t144 then perhaps we wouldn't see all the negativity at times. Yes the xmas period might downgrade over the next few days. But next time I'm going to stick to the reliable. And wait for the fi charts to hopefully come into view. Anyway onto the ECM although I might be out of the reliable timeframe just now lol.

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Evening all,

Made the mistake of coming in here tonight before I viewed the output,heres what I found when I went and looked for myself,

 

 

 

 

 

 

 

 

All the above showing cold for the big day.

 

Great potential going forward too.

 

The GEM chart translates to average for most and above average for the south: post-14819-0-66582000-1418926934_thumb.p

 

The official UKMO reading for cold is between -4 & -5C below the average: post-14819-0-44664300-1418926995_thumb.p

 

None of the above would equate to that for the south or the north IMO.  GFS P: post-14819-0-15393900-1418927181_thumb.p

 

Pedantic's aside we still have till probably the 0z on Saturday before the pattern is decided one way or other; just bad timing the trend changes this close to that deadline.

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WAY too much panic in here tonight, which is obscuring the facts.

 

Even following the great model runs from yesterday and overnight, the coldest weather wasn't really due to hit until about the 27th or 28th. That's 9-10 days away; that's FI.

 

The mere fact that we COULD get some significant cold soon is already better than last winter where I barely even saw a frost (already had several this month) let alone snow.

 

And herein we find the problem with stellar model runs; the comedown when the next run is inevitably different is really big on here. So, to all those hitting the big red button marked "oh no" or "told you so" or "hahaha", I would say read Tamara's posts; winter has barely begun and the background signs are good.

 

Snow is always more commonplace in Jan/Feb than Dec anyway. If it gets to halfway through Feb and nothing has still happened then I might begin to believe that we're out of luck again. But not yet. Hang in there folks.

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ECM looks significantly better than the GFS at +144:

ECH1-144.GIF

No chance of the trough exiting the US as fast as on the GFS(P), when we had a horribly aligned set of shortwaves phasing with the US low just off the eastern seaboard:

gfsnh-0-144.png

 

And alas the start of some WAA toward Greenland on that second chart, with Mid-Atlantic blocking likely to establish later on in the run. Fantastic charts.

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My advice would be listen to the experts, like fergieweather for example. You won't get the MO reacting so ott regarding a gfs run of all things. Wintry spell here we come!

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Not bad for Christmas Day

 

ECH1-168.GIF?18-0ECH0-168.GIF?18-0

 

A cold North Westerly flow with -4 uppers covering the whole of the UK, -6's touching Scotland.

 

Certainly not a mild boxing day either

 

ECH1-192.GIF?18-0ECH0-192.GIF?18-0

Edited by Barry95

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ECM looks better for more places to see a (official) white Christmas. Flow is N/NW at midday with -5c uppers approaching the Midlands. Could be wintry showers in the north AM and all areas by evening

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The 12Z GEM shows what I had in mind in my last somewhat cryptic post!

 

post-13989-0-47649900-1418927714_thumb.g

 

I would think the LP to the SW might be a little closer and the ridge from Greenland maybe stronger but as the cold air spreads S, the frontal zone would split, with a warm front headed W around that LP.

 

Something similar I remember happened once before at Christmas as cold air pushed the mild Atlantic air away - rain turned to snow on that occasion.

 

post-13989-0-66898500-1418928002_thumb.p

 

 

 

 

 

 

 

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So at 192 hours on the ecm were in a wsw wind???Im not sure why the big you turn but the negative nao signal is just to far west imo

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Well the ECM at least delivers a decent Christmas and Boxing day as the cold air digs in. Trouble is again the high builds just west of Greenland and the next pulse of cold air pushes into the Atlantic and starts to engage that low. Only one way from there and if the Greenland high becomes cut off then low pressure will simply slide around this and into the UK

ECH1-192.GIF?18-0

 

So we have the GFS which is all over the place, the GFS (P) and GEM wanting a decent northerly whilst the ECM wants this west based -NAO. Who knows what will happen come Christmas.

Given the clash of very cold and very mild air, rainfall and potentially strong winds could be the issue if this comes off as the steepening thermal gradient develops.

Edited by Captain shortwave

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Azores high hasn't gone to Greenland .

Greenland high pressure has been born from nothing .

For cold to come west full retrograde off the Azores high needs to be implemented.

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At least the main area of vortex has shifted now west .before any off the winter is the over posts starts

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West based negative NAO from the ECM, to complete the underwhelming outputs. Regardless of whether the ECM throws out some more appealing T240hrs chart the damage is already done.

 

Still enough time for changes thankfully as tonights outputs are giving me indigestion.

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post-12276-0-65824800-1418928828_thumb.g

Well... Iceland's getting blasted at least.

 

Icelandic low completely scuppers the deeper cold on the EC; a developing trend; but regardless, very encouraging to see the the WAA and building of Greenland/mid-Atlantic heights; strat effects may mean this is going to be a very slow build up to the coldest spell. Intriguing output from now till then.

 

It may not be instant cold, but D10 is one of my favourite charts since that projected Dec 12 easterly that never happened... magic: post-12276-0-12614500-1418929027_thumb.g

Edited by Isolated Frost

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