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DiagonalRedLine

Model Output Discussion - The Run In To Christmas

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What i dont understand is where have all the heights gone!! I mean we had some serious greenland heights at 1060 mb and they've just vanished to nothing in literally 24 hours! ! How om earth is that possible!!! Okay a slight downgrade is possible always but nothing to this extent! ! Something is seriously wrong with the models or theyve picked up on a change that wasnt expected.

That's the point, they weren't ever there and only projected to be there.  But we also have to say we aren't there yet so more changes could and probably will occur.

 

BFTP

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How important is this - NAO and SSW?

It is talked a lot on here but is it the be all and end all?

 

 

a -NAO is simply the measurement of the pressure pattern to our west.  if you take it that an icelandic low and azores high will be strongly positive and a greeny/icelandic black and azores low strongly negative then you can fiddle around inbetween.

 

clearly a -NAO would statistically give the uk a better likelihood of cold conditions but it is possible to get cold without one. (ie scandi block with the uk just able to receive the continental flow before the atlantic takes it north)

 

SSW is statistically significant re cold and viewing the strat thread will assist. again, its not a precondition for cold here.

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a -NAO is simply the measurement of the pressure pattern to our west. if you take it that an icelandic low and azores high will be strongly positive and a greeny/icelandic black and azores low strongly negative then you can fiddle around inbetween.

clearly a -NAO would statistically give the uk a better likelihood of cold conditions but it is possible to get cold without one. (ie scandi block with the uk just able to receive the continental flow before the atlantic takes it north)

SSW is statistically significant re cold and viewing the strat thread will assist. again, its not a precondition for cold here.

SSW doesn't gaurantee cold for the UK though, just significantly increases the chances as it promotes Northern Blocking

BA I know you know this, just adding

Edited by karlos1983

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At least cold air is trying to push south, last winter was a cold free zone!

 

Indeed, Some people have already have more frosts than last winter, and more severe frosts than last winter already.

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That's the point, they weren't ever there and only projected to be there.  But we also have to say we aren't there yet so more changes could and probably will occur.

 

BFTP

 

Exactly Fred, 

.

They were falsely modelled.

 

I like the way you put it.. But at the range it's been Model'd at reg the Greenland High it was always going to be false no matter what it shows.   :smiliz19:  

Edited by Polar Maritime

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.

 

I like the way you put it.. But at the range it's been Model'd at reg the Greenland High it was always going to be false no matter what it shows.   :smiliz19:

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Just looked at the gfs 06z run and that's a awful run for coldies. Think the ECM will be bang on the money. Yes it's been throwing out different output past t144 but we see that other models are moving towards the ECM solution. Also just read cohens update on the strat thread. And it's grim reading for a ssw. Now looking like late jan. I'm starting to wonder after all the background signals looking favourable if the mets lrf winter forecast will be spot on.

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Just one chart posted in the last two pages.

 

I thought this was the model thread, if you don't back up your thoughts with evidence then why bother posting?

 

Most of this should be in the moan thread where it belongs. If each posted what they think is poor then we can judge them on it.

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Deleted  I was looking at the wrong version of GFS on NW.

 

Apologies.

Edited by J10

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.

 

I like the way you put it.. But at the range it's been Model'd at reg the Greenland High it was always going to be false no matter what it shows.   :smiliz19:

Not really sure what your point is? I put exactly what BFTP put yet I'm somehow reading it wrong?

Edited by Polar Maritime

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http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

The 8-10 day 500mb anomaly charts show a strong northerly component across the UK with ridging to the W of the UK . The northern part of the ridging over Greenland is further east than yesterdays output as is the trough to the east. The last few days have seen variable patterns projected at this timescale at 500mb with the strong ridge extending west-east to the south of the UK now transferred westwards into the atlantic. It remain to be seen whether the latest forecast pattern will be replicated over the next few days but there has been a trend to a more favourable pattern for cold over recent days. Models are toying with the idea of cold outbreaks every few days. Even xmas day although not snowy looks pretty cold. With the close proximity of such cold air to our north and the presence of the Greenland Ice cap with some evidence of ice flows extending eastwards from the Greenland coast north of Iceland there must be a possiblity that any northerly outbreak although short lived could be potent bringing the prospect of snowfall to many parts.      

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Just looked at the gfs 06z run and that's a awful run for coldies. Think the ECM will be bang on the money. Yes it's been throwing out different output past t144 but we see that other models are moving towards the ECM solution. Also just read cohens update on the strat thread. And it's grim reading for a ssw. Now looking like late jan. I'm starting to wonder after all the background signals looking favourable if the mets lrf winter forecast will be spot on.

 

Really?

 

gfsnh-0-174.png?6

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So up and down and round and round the synoptic models go. Are the anomaly charts any better-well yes but not resoundingly so?

Not looking prior to 5-6 days ahead as the anomaly charts start at day 6.

 

Last evening NOAA below

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

The chart in the UK area does suggest a colder spell over and beyond Christmas but no real deep cold. That is something they have never really suggested since they began this signal of a colder flow at 500mb from north of west into the UK and a fairly rounded trough over northern Europe. Both 6-10 and 8-14 show this. It was about 4 days ago that the ECMWF-GFS outputs started to suggest something along these lines but only 48 hours ago that NOAA began to pick this up.

Hindsight is a wonderful thing! Looking at these outputs from about last Monday and the split flow into the UK area on the ECMWF version, link below, initially way west

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

over N America, today showing into the UK. All week I have never really suggested, even on my Tuesday ‘ramp’ higher than a 35-40% probability of deep cold. This morning, in terms of anything long lasting from an Arctic source probably back to 25-30%

On all 3 charts the contour that ends up over southern England has begun its travels over N America south of Alaska then south of the Gt Lakes so no deep cold and a very long sea track rather than a contour coming down from northern Greenland or north of Jan Meyen. In other words all the time the air is Polar not Arctic in origin for most of the country. Nor is there any real signal out in the 8-14 NOAA chart of this flow changing markedly or the trough extending well south into Europe.

So overall I think we are set to have mainly Polar Maritime air, temporarily southern areas associated with one or more deepening lows, just about into winter style Tropical Maritime, thanks to the marked temperature contrasts, with more northern parts keeping, for the most part, air of Polar origin. Whether any further really deep lows expected post Christmas are likely again is impossible to say from the anomaly charts. Further wind for sure as systems move quickly in the strong flow over the Atlantic and how westerly or slightly meridional that may be still seems open to either pattern to me. As to where snow may fall on low ground then the Border counties north I would think but back edge snow MIGHT occur further south with the post Christmas storm. So quite good for the Scottish ski industry but not so good for many lower level European ski resorts.

A very difficult upper air pattern to really get right let alone the surface so lots of room for many ups and downs over the festive season for many cold lovers on here.

 

Excellent analysis there John. Completely based on facts and entirely objective.

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The models' ambivalence as to what happens on or after Christmas Day continues. The spectacular looking LP for 27th would indeed be interesting, but I guess the chances of anything like it happening at this distance are pretty remote, although having said that, it is a possibility.

 

What I find odd still is that there have been no real signs within the models of a pressure build from the NW after Christmas. Pressure rises to the S or SW yes, but that is all. Several days of cold air coming S across the Norwegian Sea, LP much weaker over Scandinavia, a situation which has in the past given rise to some noteworthy frontal battle grounds between cold and mild.

 

Here's a nice example from 1982.

 

post-13989-0-95894300-1419078491_thumb.p

 

That one produced significant snow across the S as an advancing frontal zone stalled as it pushed into the cold air to the N.

 

As always, I am aware that no 2 situations are ever the same, and I wouldn't mention it but for the indecisiveness of model output at that time, but it's an intriguing possibility and, dare I say it, no less unlikely than the GFS major storm!

 

It will be interesting to see later model output and whether we have any sort of consensus developing.

 

 

 

 

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Just looked at the gfs 06z run and that's a awful run for coldies. Think the ECM will be bang on the money. Yes it's been throwing out different output past t144 but we see that other models are moving towards the ECM solution. Also just read cohens update on the strat thread. And it's grim reading for a ssw. Now looking like late jan. I'm starting to wonder after all the background signals looking favourable if the mets lrf winter forecast will be spot on.

1st of March 2015 for revision of long range forecasting.

Regards the SSW being delayed this was always a possibility and if it results in it being 3 weeks further forward, it was still a great forecast from Chino and Tony.

They assessed all the data and made a great call. What could not have been seen was the last months increase in solar energy output.

But looking at what Judah states regarding the modelling of the AO in next 5-7 days and it turning negative with the NAO following suit, I'm convinced that the anomaly charts are correct with the Greenland ridge prediction.

In the end it's personal what your feelings are but the models are struggling, some aren't even functioning (GFS P) and ECM outliers are numbering 2 runs now.

So going by Judah's forecast A -AO this week. Not that long to wait and see if true.

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1st of March 2015 for revision of long range forecasting.

Regards the SSW being delayed this was always a possibility and if it results in it being 3 weeks further forward, it was still a great forecast from Chino and Tony.

They assessed all the data and made a great call. What could not have been seen was the last months increase in solar energy output.

But looking at what Judah states regarding the modelling of the AO in next 5-7 days and it turning negative with the NAO following suit, I'm convinced that the anomaly charts are correct with the Greenland ridge prediction.

In the end it's personal what your feelings are but the models are struggling, some aren't even functioning (GFS P) and ECM outliers are numbering 2 runs now.

So going by Judah's forecast A -AO this week. Not that long to wait and see if true.

 

The GFS P is actually back (quicker than expected) and I hope that people take note of it (at least in its high resolution period).

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Just looked at the gfs 06z run and that's a awful run for coldies. 

 

How exactly is this chart for Christmas Day morning 'awful for coldies'?

 

If you had offered this chart to the forum a fortnight ago 9/10ths of us would have frostbitten off your hand for it.

Edited by West is Best

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Its one of those years where snow just doesn't want to fall and lay at lower levels

 

The best I can find away from Scotland is this

 

186-780PUK.GIF?20-6198-780PUK.GIF?20-6

 

Day 10 sees the highest totals over northern Scotland starting to drop

 

240-780PUK.GIF?20-6

 

Christmas day look dry fine and bright after a frosty start with temps around 3 to 6c

 

126-582PUK.GIF?20-6

 

Boxing day looks a bit milder away from Northern Scotland for those heading to the sales, football matches or what ever else you may have planned

 

150-582PUK.GIF?20-6

Edited by Summer Sun

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sorry frosty but to me it looks mild upto Wednesday then perhaps a fleeting cold snap over xmas. Before we're back in the milder air. The models have taken a huge jump away from cold over last 36hrs.

According to GFS as that goes so far out ???

Edited by Banbury

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