Winter Model Discussion 12Z 22/1/13 onwards.

[lorenzo]

Pub run sneaking in under the radar and mixing things up a bit... Very Interesting..

That low in immediacy is fairly bombing away now, going to be a helluva pressure drop on that in 24 hrs.

As long as Nick is still commenting on Saviour systems and not spawn of ones then we are on the right track !

[David 'Minty' Hill]

Sorry to be off topic but i think the lack of posts may be to do with the masses of snow piing up outside this evening rather than the search into deepest FI-land for more.....

UKMO looks like it may be onto something at 144 btw. It's been quite good of late hasn't it?

Ned

Been raining here really heavy for last 5 hours

To keep it on topic I have to say Greenland highs to bring cold weather but is it not usually dry and bright? Kinda makes cold a bit pointless or am I missing a valuable point and if so can it be explained please

Edited January 25, 2013 by David 'Minty' Hill

[nick sussex]

Pub run sneaking in under the radar and mixing things up a bit... Very Interesting..

That low in immediacy is fairly bombing away now, going to be a helluva pressure drop on that in 24 hrs.

As long as Nick is still commenting on Saviour systems and not spawn of ones then we are on the right track !

Yes I don't know what the UKMO would think of my terminology! I mean can you imagine P Gibbs mentioning a spawn of satan shortwave, or synoptic garbage or saviour low!lol

And of course one that got me into a bit of trouble with JH. The infamous SSO suspicious synoptic outcome!

Edited January 25, 2013 by nick sussex

[lorenzo]

Don't forget the limpet HP, which is another evolution we could well do without echoed also in the 18z. Those things like hanging around for far too long...

[bradymk]

Been raining here really heavy for last 5 hours

To keep it on topic I have to say Greenland highs to bring cold weather but is it not usually dry and bright? Kinda makes cold a bit pointless or am I missing a valuable point and if so can it be explained please

The Greenland High in December 2010 might have provided a few bright and dry days but plenty of very snowy ones too. For mine and your location, they are the best setup for snowfall in my opinion.

[Panayiotis]

Been raining here really heavy for last 5 hours

To keep it on topic I have to say Greenland highs to bring cold weather but is it not usually dry and bright? Kinda makes cold a bit pointless or am I missing a valuable point and if so can it be explained please

Yes a lot of the time they can bring settled and bright conditions, but if you have a GH which is sustained it could bring in a polar low, this is a low which its origin is from the Arctic.Associated with the low is moisture (which you probably know) but because of the northerly flow, any precipitation that falls would be snow.The greatest example is that of Dec 2010, where i got 6-8 inches of snow!

[J10]

The Greenland High in December 2010 might have provided a few bright and dry days but plenty of very snowy ones too. For mine and your location, they are the best setup for snowfall in my opinion.

Greenland High give the potential snow event for this area, and also some decent sunny weather, However they do not tent to bring severe cold,

Tentative signs though that the mild wet weather will not continue until the end of FI which did seem possible according to previous runs.

[Cheshire Freeze]

Can anyone see the resemblance between todays 18z and yesterdays?

Yep and if you run the 18z through in sequence you'll see repeated attempted ridging of the Atlantic high towards Greenland. Gets there on the final frame!

Feb could be another very interesting month

[damianslaw]

Greenland High give the potential snow event for this area, and also some decent sunny weather, However they do not tent to bring severe cold,

Tentative signs though that the mild wet weather will not continue until the end of FI which did seem possible according to previous runs.

Greenland highs can deliver severe cold, they often bring very clear skies to western parts in particular - take Dec 2010 as an example coastal parts of Merseyside which don't usually see cold temps got down to -17 degrees, albeit thanks to deep snow cover. I agree they don't tend to bring uppers much lower than -10 degrees, unlike easterlies which bring the coldest uppers, but if we have clear skies, very low minima can easily be achieved.

Dec 95 brought a ridge down from the arctic over east Greenland and we saw record cold temp in the Highlands. From an imby perspective I would rather have a greenland high than a russian/scandi high, those in the south and east who like cold probably prefer the latter, but for anyone in the north and west who wants crisp cold frosty weather and chance of polar lows they are superb.

Edited January 25, 2013 by damianslaw

[Cheshire Freeze]

Just a note....the Greenland high is probably the best feature that can be hoped for as we progress towards late winter as it will draw the airmass from a locale which has the best cold potential i.e the NE. The further we go into Feb (and especially March) Scandi highs worry me as temps and dew points start to respond to the lengthening days quite rapidly on the continent, with milder airmasses becoming more prevalent towards SE Europe (a concern if we draw air sourced from SE rather than due E especially).

Yes there are some notable cold spells in history throughout Feb and even March BUT a Greenland high all the way for me!

Edited January 25, 2013 by CreweCold

[summer blizzard]

In the short term its interesting to note that Morroco is going to get some home grown heat in 6 days with the +15C isotherm appearing.

In the longer term i like the 18z, it reflects the likely outcome i've felt of high pressure dominant to the west .

[lorenzo]

Certainly some potent evolutions within the Ens suite tonight on the 18z, scanning through a couple of stunning Northerlies and various blocked off Atlantic profiles. I think this pair with some minor tweaking would be the the kind of thing may would hope to see come to pass. Also hidden away are some very amplified changes over the Pacific.

Got to love a Friday night Pub Run to keep things mildly interesting.. no pun intended. Liam Dutton just tweeted it was 10 degrees in Plymouth whilst -1 in Leeds. BBQ Weekend !

[Cheshire Freeze]

Hey we even get a member going below -10 at the 850 level on tonight's GEFS. That'll please TEITS!

[Chris W]

If I recall rightly we are due for some SSW-related effects from the 28th onwards? If so, and given the 18z and its superb Atlantic/Greenland height development, I think the mild spell will be pretty short.

This chart at T+177 is great: http://cdn.nwstatic.co.uk/gfsimages/gfs.20130125/18/177/h500slp.png

[Weathizard]

If I recall rightly we are due for some SSW-related effects from the 28th onwards? If so, and given the 18z and its superb Atlantic/Greenland height development, I think the mild spell will be pretty short.

This chart at T+177 is great: http://cdn.nwstatic.co.uk/gfsimages/gfs.20130125/18/177/h500slp.png

Surely with that chart the extremely strong vortex over Greenland/Canada would stop any ridging north? Good development I agree though.

[Chris W]

Surely with that chart the extremely strong vortex over Greenland/Canada would stop any ridging north? Good development I agree though.

The frames leading up to the one I just posted seemed to indicate that the Canadian vortex could help to pull heights up to Greenland quite strongly. As for the vortex strength, isn't it still possible that it will be further weakend by the SSW?

[Weathizard]

The frames leading up to the one I just posted seemed to indicate that the Canadian vortex could help to pull heights up to Greenland quite strongly. As for the vortex strength, isn't it still possible that it will be further weakend by the SSW?

It is true it could propel some heights north but a vortex of that strength would just blitz any high pressure 'setting up' around that area a chart like that at THIS point looks like a typical northerly toppler in my limited experience. As to the SSW they say the biggest effects are felt 14-28 days out so we are due to see bigger effects soon, we need to hope so anyway because the vortex setting up where it is progged to is a nightmare. Unless you like Average to mild weather of course

[Chris W]

Unless you like Average to mild weather of course

I do not! I agree it wouldn't be long-lasting based on the 18z run and northerly potential, but compared to the zonal runs of late it is a considerable step in the direction of potential cold and what I've been expecting from January's chat on these forums. My own experience is that the best cold is usually in February.

[Weathizard]

Can any of the more experienced members on here answer a question for me with regards to the SSW? As the biggest effects are expected soon, do the big changes normally appear from nowhere? (if there is going to be big changes) and are SSW effects are going to make themselves known will they weaken the vortex significantly?

[swfc]

oz looks like an upgrade of sorts in the mid term but implodes in the low res.ukmo looks not to bad either ay 144 hrs still

[John Badrick]

I do not! I agree it wouldn't be long-lasting based on the 18z run and northerly potential, but compared to the zonal runs of late it is a considerable step in the direction of potential cold and what I've been expecting from January's chat on these forums. My own experience is that the best cold is usually in February.

Don't think a very cold Feb is going to happen this year I'm afraid, just hope models would show some dry days for a change

[Severe Siberian icy blast]

Don't think a very cold Feb is going to happen this year I'm afraid, just hope models would show some dry days for a change

Well I would disagree completely, and so do the pro's .

Back to the models.

The last frame on the ECM shows a complete demolition of the Canadian vortex , you can see the on the northern hemi chart the strong Siberian vortex taking controle and becoming the main player , we have a week of westerly orientated winds , sometimes southwest , sometimes west, sometimes northwest , but once we can get the remaining parts of the vortex past us , that will allow heights to build to our northwest , the last frame on the ECM shows this and the heights will only strengthen from there on.

I said lets get the weekend out the way first , I say the same now , but I do feel that we will start to see some good eye candi in the next few days.

[Gibby]

Good morning. Here is the morning report on the 00z output from GFS, UKMO, GEM and ECM for today Saturday January 26th 2013.

All models show a similar pattern throughout there output this morning which makes my job easy today as I can lump all models into one basic summary rather than look at specifics between them . The weather has taken a complete turn from the cold and snowy outlook of the past week or so. Instead we have a strong Atlantic West or SW flow blowing over the Atlantic and across the UK all courtesy of the basic pattern of High pressure to the South with a series of deep depressions passing to the North. All areas will see periods of rain and showers with temperatures well up to the seasonal normal and a bit above at times in the South. There are tentative suggestions from GEM and from GFS late in FI for pressure to build to the NE as the Atlantic train weakens but these are rather weak signals at this stage with the vast majority of members within the Ensemble group of GFS keeping things at least at normal temperature values after a few milder blips in the early days of next week with a continuation of the Atlantic feed the more likely evolution perhaps with a trend to a somewhat more chilly zonal pattern later on as the Jet Stream which blows strongly over the UK in the next week continues unabated.

So in Summary a sustained spell of windy and less cold weather is shown today with patience having to be adhered too before any specific trend is highlighted towards a return of anything more wintry. There will be plenty of rain and showers for all in the coming spell with some very windy weather too.

[MillinMan1]

I still think February is going to be an interesting month.

The last couple of days I've noticed that the ECMWF is keen to get some colder air being dispatched from the north. It does go into Scandinavia but it's encouraging. http://images.meteociel.fr/im/7875/gensnh-0-0-174_kmw9.png

Also GFS ENS does show some cold air into February from the north/north east.

http://images.meteociel.fr/im/9998/gensnh-0-0-174_sas1.png

Last of all I want to draw your attention to the CFS z200 heights for February. A lot of blocking over Greenland and possibly towards our west!

http://origin.cpc.ncep.noaa.gov/products/people/wwang/cfsv2fcst/imagesInd3/glbz200MonInd1.gif

Interesting times ahead indeed...

[Frosty.]

The latest gfs and ecm 00z operationals thankfully not showing much mild weather in the outlook, tuesday still looks the mildest day in southern britain but cooler further north, the gfs 00z tries to drag arctic air south after midweek but doesn't dig far enough south, there are signs in FI that the jet will have a more nw/se or at the very least wnw/ese profile which would bring some shortlived colder incursions as depressions push across with some colder frosty weather as ridges push east, there are also signs of cold blocking to the northeast. So in summary, in the short term it will be turning milder, very wet and windy, especially for the north and west although on sunday afternoon the showers in the north and west could become wintry on hills, then from midweek the temps should fall back to around average and even a risk of brief cold incursions, especially further north with wintry showers and night frosts. I get the feeling that the models are getting very mixed signals from around T+144 hours and that another cold snap or spell won't be far away.

The biggest concern now is the increasing amounts of flooding in the coming days due to rapid snowmelt and heavy rain.