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Model Output Discussion - The Run In To Christmas

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Morning again,

One thing clear from the ensembles the operational run from the GFS  was one of the milder  solutions,

MT8_London_ens.png

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GFS P snow depth charts are showing a high of 50cm (19 inches) and widely 7 to 15 inches for higher parts

 

Firstly a white Christmas is looking restricted to some higher parts of Scotland

 

168-780PUK.GIF?18-18

 

Not much change on Boxing day

 

192-780PUK.GIF?18-18

 

By the 27th most of the snow is gone but............

 

216-780PUK.GIF?18-18

 

....... By the 28th look whats fallen in 24 hours!!

 

240-780PUK.GIF?18-18

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I was about to post that I don't think it's at all clear. I really don't. We have ECM still going for something that would be very cold through Christmas leading to a stonking northerly and GFS showing wind directions 180 degrees the opposite.

 

We are in a pattern change and I suggest nothing at all is clear at the moment, and probably won't be until Monday.

Morning mate.

 

The reason the outlook is clearer to me is because don't forget my forecasting style is based on instinct. My approach is to look at the output and figure out what is most likely to occur and where the models might be wrong. The events I detailed in my previous post are very likely to occur in my opinion especially the return of the milder, unsettled W,lys. However I am very confident it will turn much colder towards the end of the year into the New year.

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We have now narrowed down the likely temperature on the 27th to the range of -6 to +12, eliminating everything from -8 to -7 and +13 to +14.:)

 

And I'm not kidding.

 

I prefer the colder solutions, after reviewing what the milder ones do with the North American low. The GFS over-deepens it and retrogrades it sharply almost past Manitoba. This won't happen. The GEM on the other hand is overly progressive with it. So I like the middle course taken by the ECM and figure that everything downstream is therefore more plausible. The west of Azores low on the GFS has too much room to develop with that bogus retrograde, and on the GEM it gets picked up by the overly progressive North American low. Both outcomes are about the same in terms of moving it steadily northeast towards Faeroes to Iceland region. That would of course end the brief cool snap and return things to very mild by the 27th. But the ECM says the Azores low has a lot of work to do to move northeast, gets no help and has to do all the lifting. By the time it arrives, cold air is waiting for it. Would likely give the heaviest snow to central Ireland, Wales, Midlands and northern England. But as some have said, these scenarios then have a tendency to reset further south if they are favoured at all.

 

 

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How do you see it going BA ?

Broadly, ' I agree with dave'!

Perhaps some flesh on the bones later

Edited by bluearmy

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As others have said don't get hung up on 1/2 runs, Look at the broad overall pattern/theme.. To me nothing has changed this morning, A cool/cold shot around Christmas from the North before a push a of milder air, It's beyond that where the uncertainty lies and will do for a good few days yet. But the signals remains for a 2nd much stronger push of Height's over Greenland.

 

ECH1-240.GIF?19-12

Edited by Polar Maritime

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From my time watching the charts once they flip this close to T0 then it is unlikely they will flip back. However the spread is so high that making any conclusions just yet would be rash:

 

attachicon.gifgens-22-1-240 (1).png  The mean offers hope: attachicon.gifgens-21-1-240 (5).png

However the hi-res led the ensembles towards the Atlantic ridge and it took several runs before they came on board. It could be the case in such an uncertain synoptic that the ensembles will only gradually flip back to the op. Until we know D8 the rest of FI is rather mute.

 

GEM is still amplified but the cold has shifted east so very little of wintry interest up to D10: attachicon.gifgemnh-0-240 ( 8).png

 

I am not sure UKMO is going anywhere, certainly a downgrade at D6: attachicon.gifUN144-21.gif

 

There are cool uppers but it is a rather underwhelming. Looking at the ECM, if you strip it down ignoring the "potential" all you have is the same pattern, a brief N/Nw'ly (d6), a ridge (d7), followed by a LP (d8). D9-10 is usually outlier territory so can be arguably ignored.

 

Just ordinary December fare whilst we await the early Jan strat effects.

 

But IDO, if you are looking at the models as a whole, one of them (at least) will have to flip because in broad terms the GFS is saying mild and the ECM (and others) are saying northerly blast.

 

Clearly, therefore, one of them has got it wrong and will eventually have to come sulkily to the party when the relevant model realises.

 

FI is very close at the moment, only the next 3 days or so is clear.

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Slightly off topic do apologise mods. But intresting tweet from Ian Ferguson this morning. Forecast upto xmas seems good. But then goes onto tweet much colder and below average into new year with servere weather possible. Now read into that what u will.

Very odd he is talking about the New Year so far out

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I'll keep it short and sweet this morning!

 

Prospects for cold from each model :

 

GFS- dire

GFS P- underwhelming verging on dire

ECM- uncertain, continued tease at T216 and T240hrs

UKMO- could go the same way as the ECM

GEM- nice looking block to the nw but at T240hrs the UK is still the wrong side of the trough

 

Ensembles- GEFS all over the place, the ECM mean does at least get troughing east of the UK however because of the complicated nature of the set up these won't really be able to deal very well with shortwave phasing issues.

 

Overall a little colder Christmas and Boxing Day.

 

I think some sort of blocking to the nw is likely but its a case today of whether the outputs can edge this far enough east and se to force low pressure into mainland Europe.

 

This is not a given and so the outlook is uncertain, if the western based negative NAO can edge towards a more central type scenario then a chance for some snow and much colder temps, if not then its a case of another tragic disappointment.

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Very odd he is talking about the New Year so far out

 

Actual tweet:

 

  fergieweather

W COUNTRY F'cast confidence good to Xmas Day but post-26th tricky. Expected colder than average to New Year. Periods of severe weather poss.

19/12/2014 08:19

 

Not talking about New Year plus. ECM Mean at D10 highlights the potential: 

 

post-14819-0-71331200-1418978168_thumb.g  post-14819-0-60285900-1418978176_thumb.g

Edited by i'm dreaming of...

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Actual tweet:

 

  fergieweather

W COUNTRY F'cast confidence good to Xmas Day but post-26th tricky. Expected colder than average to New Year. Periods of severe weather poss.

19/12/2014 08:19

 

Not talking about New Year plus. ECM Mean at D10 highlights the potential: 

 

attachicon.gifEDM0-240 (1).gif  attachicon.gifEDM1-240 (3).gif

I didn't say he was talking about the period beyond the New Year, I have read the Tweet ,,,,,,,,,,,,,,,,,,,,Many thanks, he mentions up to the New Year , which is so far out

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Actual tweet:

 

  fergieweather

W COUNTRY F'cast confidence good to Xmas Day but post-26th tricky. Expected colder than average to New Year. Periods of severe weather poss.19/12/2014 08:19

 

Not talking about New Year plus. ECM Mean at D10 highlights the potential: 

 

attachicon.gifEDM0-240 (1).gif  attachicon.gifEDM1-240 (3).gif

Which of this mornings run would support those remarks I wonder? Nothing we have seen would support..

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This is not a given and so the outlook is uncertain, if the western based negative NAO can edge towards a more central type scenario then a chance for some snow and much colder temps, if not then its a case of another tragic disappointment.

 

Looking on the strat Discussion they are talking about the possible split leaving a negative west based NAO. Early days yet.

 

https://forum.netweather.tv/topic/81567-stratosphere-temperature-watch-20142015/page-40

Edited by i'm dreaming of...

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The GFS output almost reminds me of the great let down a couple of winters ago where at around t.48, the promised N'easterly that looked set to bring severe cold and snow simply vanished.... The last few runs on the GFS models are heartbreaking. Even the Xmas cold shot has been downgraded while the period after is looking stormy and very wet.

 

I know the past weeks output has been very promising, but this isn't the first time I've seen this happen, nor do I expect it to be the last.  :smiliz46: 

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Actual tweet:

 

  fergieweather

W COUNTRY F'cast confidence good to Xmas Day but post-26th tricky. Expected colder than average to New Year. Periods of severe weather poss.

19/12/2014 08:19

 

Not talking about New Year plus. ECM Mean at D10 highlights the potential: 

 

attachicon.gifEDM0-240 (1).gif  attachicon.gifEDM1-240 (3).gif

 

................it's also possible to win the national lottery! ;)  

 

What a tease!

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And for a sensible level headed look at the probabilities I do suggest some of you tune in to the BBC weather video out to late next week. Sensible down to earth ideas on what MAY happen with charts to support that idea.

I will update re the anomaly charts later on as the EC-GFS am output is not yet out-I doubt they will show any major change from what I have been showing for the last 2-3 days.

Edited by johnholmes

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Which of this mornings run would support those remarks I wonder? Nothing we have seen would support..

 

Well the UKMO looks interesting at 144,UN144-21.GIF?19-06 

ECM Mean develops quite nicely............ still!! @216 EDH1-216.GIF?19-12

 

As do a number of the GEFS Purbs for example P13 gensnh-13-1-180.png?0

 

plus whatever extra they see that we don't,  so potential is definitely there IMO.......

Edited by karlos1983

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Slightly off topic do apologise mods. But intresting tweet from Ian Ferguson this morning. Forecast upto xmas seems good. But then goes onto tweet much colder and below average into new year with servere weather possible. Now read into that what u will.

to be very honest im starting to feel the models are going to flatten the pattern once again theres a broad sense that things are moving away swiftly from a colder outlook although favoured spots are still in with a shout of wintry stuff.

 

country wide event is looking very unlikely now and this chart from the ecm shows the swift destruction of our only hlb into greenland.....

ECM1-240.GIF?19-12

 

over all the models have moved away like i suggested the other day the core of cold spills into scandi area and eastern europe and once again its a case of close but no cigar.

 

im dissapointed but not suprised by the downgrades!

 

i think hopes on anything at the start of jan are certainly moving swiftly away from what was seen a couple of nights ago !

 

all of the gfs runs  suggest the same...

but the chart i like the most is the gem and moving forward although looks complicated but shows better chance of longer term cold but its the gem and although like the ecm nowhere near as good as the ecm but worthy until 144 to 168 beyond its rather erratic.

gem-0-240.png?00

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  fergieweather

W COUNTRY CONT'D Key thing we will be watchful for end Dec are deep areas of low pressure & resultant disturbed weather. A watching brief.

19/12/2014 08:38

 

IF added to prev tweet. So looks like a possible threat of storms. The GEFS also hinting at that: 

 

post-14819-0-13538600-1418978923_thumb.p

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Slightly off topic do apologise mods. But intresting tweet from Ian Ferguson this morning. Forecast upto xmas seems good. But then goes onto tweet much colder and below average into new year with servere weather possible. Now read into that what u will.

There literally is only one way of reading into this.

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Again I think we'll see a failed attempt at full on deep cold blast and models are still at loggerheads.  I think cold will arrive at our shores but will need more than one bite at the cherry.  I think any cold for Christmas will be the first bite.    My concern for this winter so far is heights either around the Azores / Europe wants to stubbornly remain and not get sucked up to higher latitudes.  Take a look at this UKMO, from there the trough won't be allowed to dig S/SE enough IMO hence it'll get held and then shunted east.

 

So for me, a cold seasonal shot to come, but I have this niggling feeling that it won't be the winter catalyst.....looking a strange winter this one

 

 

BFTP

 

UW120-21.GIF?19-06

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Looking on the strat Discussion they are talking about the possible split leaving a negative west based NAO. Early days yet.

 

https://forum.netweather.tv/topic/81567-stratosphere-temperature-watch-20142015/page-40

Oh! There are still variations on that west type scenario but you can't really sustain cold with that because the jet curve back near the UK will eventually edge too far west.

 

Judging from Ians tweet then the block must get sufficiently east eventually to force low pressure track into France, its unlike him to ramp anything up so hopefully things might fall into place.

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So another day of model watching to come and we're no nearer to the outcome post Xmas than we were  a couple of days ago. I've always favoured a cold snap quickly followed by the familiar mobile Westerly regime but this still could go either way at this stage and won't be resolved until early next week IMO. I must say I've never seen such a huge difference between the ECM and GFS in a log while, talk about polar opposites.

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Oh! There are still variations on that west type scenario but you can't really sustain cold with that because the jet curve back near the UK will eventually edge too far west.

 

Judging from Ians tweet then the block must get sufficiently east eventually to force low pressure track into France, its unlike him to ramp anything up so hopefully things might fall into place.

I think that could change again over the next few days Nick as the MetO appear to be struggling post Xmas also and is it any wonder when you compare the GFS and ECM, though the MetO don't take much notice of the former.

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