Winter Model Discussion 12Z 09/01/13> The hunt for cold ?

[The Eagle]

GEM is actually moving away from the ECM unfortunately - more toward GFS with the jet stream profile.

[rory o gorman]

another reason why a bad ens would worry me is how many times in the past have we seen the gfs lead the way in a blocking pattern and to be slowly followed by the others before it picks up energy off the eastern sea board again in the mid/short term and it comes to fruition.

[beefy201]

Sorry to dissapoint but not a chance!!!! the rain/sleet/snow line on saturday/sunday will be south of the M4 the good news is that i think we will see a much better attack from the east closer to midweek next week! more on my perception on thinks tommorow lunch

Edited January 9, 2013 by beefy201

[AWD]

NAE has the colder air arriving earlier than the GFS & UKMO, with the -5hpa line over the Midlands on Friday;

And -8hpa temps touching Anglia;

One thing I note is a bump in the depression to our west, suggestive of E/SE travel. Is this suggestive of a better undercut or not?

Edited January 9, 2013 by AWD

[fergieweather]

Rather that than the UKMO Northerly. But that is a very IMBY statement!

Main thing is we have seen a good shift back towards the EC/UKMO from this afternoons GFS early on.

Do bear in mind UKMO effectively dismissed their 00z run as an outlier and it was modified almost completely to match EC. So we've yet to learn the Chief's views on this latest run.... they'll await EC with interest.

[Slowpoke]

GEM rolling out and looking good so far, band of snow crossing the country on the 12z with bitterly cold air flooding in from the east.

Drop a couple of CMs of snow, let the proper cold air establish, watch those temperatures fall.

Then we'll have some N and E reloads to top-up

Then it can warm up late-Feb

TY

But in all seriousness, I like this precip chart as it brings us in Western England a better chance of some snow over the weekend!

[fergieweather]

Sorry to dissapoint but not a chance!!!! the rain/sleet/snow line on saturday/sunday will be south of the M4 the good news is that i think we will see a much better attack from the east closer to midweek next week! more on my perception on thinks tommorow lunch

Not necessarily. UKMO view is likelihood of light snow across fair swathe of central-southern England by end of Sat, but not considered disruptive.

[Schmalex]

I'm confused, chaps.

I am a mere beginner to all this and read this (and other) threads with great interest. However, I am baffled when I read two very authoratitively written contributions, placed almost consecutively on a page where the first one reads "12z GFS looking good, much better than the 0z" and the subsequent post, refering to exactly the same model run reads "12z GFS a complete horror show".

How can this be? Surely there is only one way to read a model and everyone commenting on the models in the run understands what they are looking and how to interperet the results, so why such disparity in the comments?

Edited January 9, 2013 by Schmalex

[Naturist-Holiday.com]

The GFS 12Z is more often than not over progressive with the Atlantic beyond T+144.

I suspect we will be looking at the very cold 850hpa temperature's staying in place across most parts of the United Kingdom next week, with the driest and sunniest weather confined to the west and north. With pressure remaining lower to our east and south the threat of slow moving snow showers or longer spells of snow sliding down eastern England.

The coldest temperature's will be IMO across the west Country and Wales early next week, under clear skies, light winds and any snow-cover from saturday's elongated front - 17C possible. Some southern Counties may get a fair few hours of snowfall...... and when you translate 1mm of rainfall is equal to that of 1cm of snow..... A few inches 'at least' in some areas along the M4 Corridor.

Lets hope the Nogaps T+144 chart that TEITS uploaded comes to fruition........ .

NH

Edited January 9, 2013 by Naturist-Holiday.com

[Summer Sun]

GFS is following on from the 06z run in bringing in milder weather by mid next week, UKMO isn't having it though and keeps us in the colder air, A forecasters nightmare for sure

However UKMO is colder and more blocked

[bradymk]

Well its so painful waiting for these runs, GEM currently trickling out, another good run, much better than GFS anyway, huge 6-7pm tonight, more servers may be needed Paul

[cold snap]

Gem going down the gfs line here,

The low around the Greenland area Stops the ridging off the Greenland high

However things looks cold over the weekend

[Snowman.]

What with the Heights in Scandinavia on the GEM?

Looks like Surface heights?

[Slowpoke]

I feel for the weather forecasters. Watching them today has been really cringe-worthy, as many have admitted that they just can't forecast past Friday at the moment. All they've said is "it's going to get colder and it may be prolonged and snowy". Sucks to be them right now!

[shuggee]

I'm confused, chaps.

I am a mere beginner to all this and read this (and other) threads with great interest. However, I am baffled when I read two very authoratitively written contributions, placed almost consecutively on a page where the first one reads "12z GFS looking good, much better than the 0z" and the subsequent post, refering to exactly the same model run reads "12z GFS a complete horror show".

How can this be? Surely there is only one way to read a model and everyone commenting on the models in the run understands what they are looking and how to interperet the results, so why such ambiguity and disparity in the comments?

My take would be that this is because one person is looking at Monday/Tuesday where indeed the 12z GFS Is a big improvement on the 06z. But the second person is moving onto Weds next week and it's back to westerly zonal weather on the 12z GFS, whereas the European models are suggesting (along with the constant anomaly charts that don't swing wildly like every run) that mid week next week will be a blocked pattern with continuing cold across the UK.

So, it is both looking much better, but then a 'horror show'!

[Snowman.]

I'm confused, chaps.

I am a mere beginner to all this and read this (and other) threads with great interest. However, I am baffled when I read two very authoratitively written contributions, placed almost consecutively on a page where the first one reads "12z GFS looking good, much better than the 0z" and the subsequent post, refering to exactly the same model run reads "12z GFS a complete horror show".

How can this be? Surely there is only one way to read a model and everyone commenting on the models in the run understands what they are looking and how to interperet the results, so why such disparity in the comments?

Upgrades in short term caused the block too last longer but toppled and turned into a horror show and went against 500mb heigh anomaly charts.

[weatherguy]

I'm confused, chaps.

I am a mere beginner to all this and read this (and other) threads with great interest. However, I am baffled when I read two very authoratitively written contributions, placed almost consecutively on a page where the first one reads "12z GFS looking good, much better than the 0z" and the subsequent post, refering to exactly the same model run reads "12z GFS a complete horror show".

How can this be? Surely there is only one way to read a model and everyone commenting on the models in the run understands what they are looking and how to interperet the results, so why such ambiguity and disparity in the comments?

It's all about perception unfortunately

It definitely is much better than the 12z, no real doubt about that. HOWEVER, it certainly is not good out into FI. Now, it's then up to perception whether the fact that the short term is better shows a sign of a backtrack, or whether the long-term is just too bad (which it would be if it verified) in terms of long term cold prospects.

My view? 12z is an improvement but not great for long term cold. I would like to think it will improve more in the 18z but we'll have to wait and see on that; a vital 12z ECM coming up later and we must hope it sticks to its guns!

Edited January 9, 2013 by weatherguy

[swilliam]

For the medium, term cold we seemt o be reliant on the shortwave near Iceland dropping SE. It is about to happen on the GEM but did not do this on the GFS.

[beefy201]

Not necessarily. UKMO view is likelihood of light snow across fair swathe of central-southern England by end of Sat, but not considered disruptive.

Sorry Ian but my reply was in the wrong place, was replying to someone "up North"

But i do not see the low coming in from the south west doing much more than pivoting and been pushed s.e. across france.

[Isolated Frost]

To Ian Fergusson

was just wondering what the general UKMO view was on convective shrs on Sat, Sun and Mon for NE England and SE Scotland- in the general SE turning E flow, I was wondering whether much convection is expected to be sparked off, plenty cold uppers there- just not quite the best 500mb profile with a upper high nearby? Was wondering what Exeter made of the issue- ta

[bradymk]

HOWEVER, it certainly is not good out into FI.

Pointless looking too far ahead, especially into FI when we do not know which model has the correct pattern in the shorter term. Which ever models have the short term wrong, then they will be wrong longer term too.

Edited January 9, 2013 by bradythemole

[Ali1977]

GEM looked to be following GFS but at 138 -8 850 head west again

[Isolated Frost]

GEM digs in the upper trough a bit later than 00z run, but end result at 168 will be about similar- another run that takes the UKMO, EC line of thinking instead

[Thundery wintry showers]

I'm confused, chaps.

I am a mere beginner to all this and read this (and other) threads with great interest. However, I am baffled when I read two very authoratitively written contributions, placed almost consecutively on a page where the first one reads "12z GFS looking good, much better than the 0z" and the subsequent post, refering to exactly the same model run reads "12z GFS a complete horror show".

How can this be? Surely there is only one way to read a model and everyone commenting on the models in the run understands what they are looking and how to interperet the results, so why such disparity in the comments?

I think it relates to why Pete has been constantly posting links to the Model Mayhem thread- unfortunately the thread has become swamped with 1-2 liners posting value judgements on what the models are showing and not a lot of substance, and that tends to lead to confusion.

The reality with the GFS 12Z is that in the short term (out to T+144) it is quite a snowy-looking run- some light to moderate snowfalls are likely in southern England on Saturday (though marginal - possibly sleet/rain near the south coast) and then we get colder brighter weather move in on Sunday/Monday with scattered snow showers for SE Scotland and down the eastern side of England, particularly NE England and Lincolnshire. In the longer-term though the northern arm of the jet powers up and we move into a mild pattern with high pressure to the south and lows moving across to the north- hence the comment about a horror show.

This evening's UKMO is less potentially snowy out to T+120, with a shorter-lived easterly on Sunday, but then by T+144 we get a full-on northerly with strong blocking over the Greenland/Iceland area, so the UKMO evolution would be more likely to produce a cold snowy spell starting around mid-January and lasting for upwards of a few days.

Edited January 9, 2013 by Thundery wintry showers

[Bobby]

Snowfest on Monday for the West on the GEM, similar to ECM, somewhat less heights around Greenland but overall looks good, I think the WAA would probably strengthen heights Greenland way if it went much further, a decent low pumping warm air up there.

Edited January 9, 2013 by Bobby