Model Output Discussion 19th January 2014-18z onwards.

[winterof79]

Yes, the kind of charts posted to suggest widespread snow on Saturday can be notoriously inaccurate/misleading at T+48hrs, let alone T+132hrs. As you suggest transient, localised falls currently look about the best on offer based on those charts, with ground above about 200-300m standing the best chance of picking up a temporary covering.  Considering the overall pattern however, I'd be extremely surprised to see what is being progged post T+72hrs getting delivered, plenty more chopping and changing to come even in the relatively short term imo. 

I must take you up on your point.

I was showing what the suggested output was according to the 06z GFS not me, people on here can make there own mind up.

Equally one could say that your prediction above is misleading as the GFS output would bring snow to lower levels up here.As "Im Dreaming" responded,looking more favourable for the North/North East.

Edited January 20, 2014 by winterof79

[R.P. McMurphy]

Little change in the ensemble means at 10 days out, cyclonic westerlies over UK. Seems to back up the Met Office outlook, signs of perhaps something stirring but this is a good best guess at the moment I think looking ahead until we see something more concrete showing with regards to a cold spell

 

NAEFS   ECM

GEFS GEM

 

It's best to add Cold Westerlies with the potential for snow on them above charts. Although the feed is more a WNW.

 

 

 

 

[mickpips]

It does appear the Met Office are getting a little ahead of themselves :
 

Headline:

Dry and cold with widespread mist or fog.

This Evening and Tonight:

Dry and largely clear with light winds allowing mist or fog to become more widespread compared to the previous night. A slight frost will also develop, leading to a risk of icy patches on untreated surfaces. Minimum Temperature -2 °C.

Tuesday:

Widespread fog initially, but through the morning the fog will lift into low cloud. During the afternoon becoming breezy, remaining cloudy and dull, with rain into the west by midnight. Maximum Temperature 5 °C.

Outlook for Wednesday to Friday:

Wednesday rain slowly clearing away eastwards, with mainly dry conditions following. Thursday cloudy with showers. Friday starting dry before strong winds and rain arrive later, perhaps briefly preceded by snow.

Issued at: 1600 on Mon 20 Jan 2014

 

 

Only one slight change on their output for my location since their last output and thats the word 'snow' which was previously 'sleet'

[shedhead]

I must take you up on your point.

I was showing what the suggested output was according to the 06z GFS not me, people on here can make there own mind up.

Equally one could say that your prediction above is misleading as the GFS output would bring snow to lower levels up here.As "Im Dreaming" responded,looking more favourable for the North/North East.

I was referring to this, not the charts you posted.

 

 

 

Also said the same in an earlier post.....

 

Shedhead

Indeed...the 06 ENS have the Op rather more in the middle of the solutions, rather than one of the coldest as it was on the 00. Still think we are a long way from seeing the post T+120hr evolution decided, but for now I think the milder Atlantic option is probably slight favourite to win out overall. However the farther northeast you are, the better your chances of seeing some of the white stuff, especially on high ground. 

Edited January 20, 2014 by shedhead

[tight isobar]

Many many posts flagging up snow potential and non potential. Perhaps some should use the evolution problems modeling has had with eas/west bias, and unbiased , with incur non incur via milder colder solutions. Even with favourable cold in place from the offing, apart from the highest elevations, it almost becomes a now cast situ, in regards precipitation snowfall .uk.the smallest gradients will have there say in such situations we may face over the coming week or, so.in a nutshell once again unit +48 modeled for precipitation cast eyes to the devolping situ at hand, then when fruition is established local geographical canbe flagged and with more precision than, present.some could almost torture one's self focused on such possible borderline scenarios at this stage.

[Bobby]

It's best to add Cold Westerlies with the potential for snow on them above charts. Although the feed is more a WNW.

 

Could be some snow around if we get NWlys but polar maritime NWls rarely deliver snow to lower levels in my experience, am quite high up here and we need about -7c uppers to get snow that sticks and that rarely lasts. A proper arctic pull of air is what we really want, could happen if we get some strong amplification. Speculation anyway, lets see what happens as we get closer.

[phil nw.]

Whilst we are not out of the game yet wrt a cold pattern we do need to see the upper trough setting up further west than currently modeled.We would then be placed better to draw that cold west over the top of any sinking low pressure going south in to the continent with heights building back west over the top.

We can see how the cold gets closer in the next few days.

 

Looking at the wider picture and at the 00z height anomalies they do have that trough disrupting across the UK by T168

http://www.meteociel.fr/modeles/ecmwf/runs/2014012000/EDM101-168.GIF?20-12

http://modeles.meteociel.fr/modeles/gens/naefs/run/naefs-0-0-162.png?0

 

which indicates a flow from the west winning through.

 

This is why a little westward adjustment of the pattern would make such a difference.

Normally the accepted trend is as shown in the ens means but in this situation with a stubborn blocking setup just across the N.Sea holding a weaker Atlantic at bay there is still room for adjustments to the overall positioning of the wavelengths.

A little more upstream ridging would help to draw the position of the trough back a little so this is something to look out for in later runs.

 

 

 

[winterof79]

I was referring to this, not the charts you posted.

 

Yes as i posted above they are a bit chocolate teapot ish.

 

Unlike this fax chart which has some 528 Dam in the mix

http://www.weathercharts.net/noaa_ukmo_prognosis/PPVL89.gif?31415

[shedhead]

Yes as i posted above they are a bit chocolate teapot ish.

 

Unlike this fax chart which has some 528 Dam in the mix

http://www.weathercharts.net/noaa_ukmo_prognosis/PPVL89.gif?31415

You really want to see sub 522 tho, that fax chart IF it were to verify would be unlikely to produce lowland snow in all but the heaviest bursts of ppt imo.

[gottolovethisweather]

You really want to see sub 522 tho, that fax chart IF it were to verify would be unlikely to produce lowland snow in all but the heaviest bursts of ppt imo.

 

That Fax Chart is a thing of beauty IMO (given the fact it receives added human input etc.) with a Front out West bumping into an incoming Front from the East, when have most of us even seen such a chart this winter?   I'm not posting this from an IMBY perspective or am looking at surface level specifics as you appear to be doing either, Shed. Anyhow, whatever you feel, go with it. I bet this chart would be welcomed by many given the possibility of snow at elevation and perhaps lower levels, guesswork until less than at t-12 hours so history would dictate, though. It should also please those unfortunate folk who have been plagued by the flooding and also the farming community who desperately need their fields to start drying out, any lying snow longer-term (longshot!) would chill the soil. Baby steps now but who knows where next week will lead us. Eyes down for the first of this week's more reliable output suites and as I stated earlier, stand back and take things from a wider viewpoint folk as even the actual synoptics are likely to change over the coming couple of days. Only start contemplating if, where and when snowfall might occur come Wednesday and beyond would be my advice.

Edited January 20, 2014 by gottolovethisweather

[Staffordshire]

Very interesting set of 12z's coming up, I'm most interested to see if

ECM sides with gfs and UKMO

[frosty ground]

You really want to see sub 522 tho, that fax chart IF it were to verify would be unlikely to produce lowland snow in all but the heaviest bursts of ppt imo.

Not really it really does depend on the synoptic's thou.........

[TSNWK]

Hello.. any news on the NAM or SRF local US models.... For upstream early clues....

[pandit-scholar]

The GFS 12z coming out now. The one positive I am taking from this so far is the potential cold pool developing in continental Europe, within a realistic time frame. If it happens, I hope the UK can take advantage of it at some stage.

Edited January 20, 2014 by pandit-scholar

[gottolovethisweather]

Bank.

 

At t+78 hours too, assuming there is precipitation around, a few of us would be happy with this. As ever, thereafter the GFS 12z wants to bulldoze the Jet in and push the Scandi High away, WE SHALL SEE!

 

 

[Summer Sun]

It looks like milder air will push in during Friday maybe some leading edge snow in the east for a short time?

 

 

The milder air doesn't hang around long though

 

Edited January 20, 2014 by Summer Sun

[R.P. McMurphy]

Bank.

 

GFS 12z 200114 Thickness 500-1000hpa & SLP at t+78.png

At t+78 hours too, assuming there is precipitation around, a few of us would be happy with this. As ever, thereafter the GFS 12z wants to bulldoze the Jet in and push the Scandi High away, WE SHALL SEE!

 

Bank:

 

Edited January 20, 2014 by Glenn W

[pandit-scholar]

Looks like the UK is in between a very cold mass based in Scandinavia and a mild one from the Atlantic. A real battleground!!

[Cecil Hogmanay Melchett]

Well im still hopeful of something more wintry but the meto update is a bit of a disappointment really.

Friday still looks potentially snowy (albeit transient) for those with altitude as the front bumps into colder air.

After that its all about trends,hopefully they will be positive

[Mucka]

Decent GFS 120h for longer term prospects with more energy getting SE

 

Edited January 20, 2014 by Mucka

[gottolovethisweather]

The 850s aren't too bad in just three days time, according to the UKMO, all things considering. If picking holes in this chart, you might need to drop the 850s slightly lower I guess but hill snow ore leading edge snow out West looks a distinct possibility, but then what come the next chart?

 

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Edited January 20, 2014 by gottolovethisweather

[Mucka]

Perhaps a surprise snow event for some in the North on Thursday?

UKMO 850's/GFS precipitation charts - note UKMO has colder upper air than the projected GFS ppn chart.

 

 

GFS slowly getting to grips with the Polar heights through the mid term as expected.

 

 

And also firing up the jet,stormy but let battle commence.

 

Edited January 20, 2014 by Mucka

[gottolovethisweather]

Bank:

 

 

Easy lad, timing is everything now.

[Bobby]

GFS 12z showing a brief period of leading edge wintriness in N/E parts before turning back to rain. 102, 108hrs:

 

 

The colder uppers are coming down from the NW so not sure how it's a battleground? Not a traditional one anyway. The  cold from the east stays there with the colder air from the NW joining up, a bit odd lol

 

- source of colder uppers

Edited January 20, 2014 by Bobby

[gottolovethisweather]

Well im still hopeful of something more wintry but the meto update is a bit of a disappointment really.

Friday still looks potentially snowy (albeit transient) for those with altitude as the front bumps into colder air.

After that its all about trends,hopefully they will be positive

 

The much quoted MetO sounds realistic TBF but I bet they would prefer to get Friday/Saturday out of the way beforehand, Shannon wotsaface anyone? Come the weekend, SW flow NW flow, NE flow, E dominated flow? Take your pick.

Edited January 20, 2014 by gottolovethisweather