Model Output Discussion - 2nd March Onward

[TEITS]

I used the word incredible to describe yesterdays 0Z ensembles but this morning they are nothing short of outstanding and the lowest I have ever seen, even including the winter months.

http://cdn.nwstatic.co.uk/ensimages/ens.20130306/00/t850Cambridgeshire.png

A mean of -14C in March!!

The ECM also brings in 850s around -12/13C.

UKMO continues to be the odd one out but very slowly this model is swinging towards the ECM/GFS.

[winterof79]

GFS OOZ still too quick with the evolution i think sinking the high

http://www.wetterzentrale.de/pics/MT8_Manchester_ens.png but v cold

http://modeles.meteociel.fr/modeles/gfs/runs/2013030600/gfsnh-0-114.png?0

ECM still consistant http://www.meteociel.fr/modeles/ecmwf/runs/2013030600/ECH0-144.GIF?06-12 and v cold

UKMO milder option http://www.meteociel.fr/ukmo/runs/2013030600/UN144-21.GIF?06-06

[Weather-history]

Crikey, no comment of the 0z outputs?

GFS mean shows virtually the whole of British Isles in -10C air at Sunday/Monday midnight. How often do you see that let alone nearly mid March?

The GFS 0z op run has pockets of -14C air over England and Wales during the early hours of Monday.

As for UKMO, well just look at the latest forecast

Outlook for Friday to Sunday:

Generally cloudy and breezy with outbreaks of rain or drizzle throughout. Hill fog likely too in many areas. Temperatures near normal at first but getting progressively colder.

Issued at: 0400 on Wed 6 Mar 2013

So the Met Office are suggesting it is going to get colder.

[Ian Brown]

The UKMO is a nudge towards the ECM, whilst the GFS and it's ensembles are bullish on the quick easterly evolution at the weekend. ECM is consistent with last nights run.

[Paul]

I can't say I can remember a time that the GFS and it's ensembles were so bullish about a scenario which is still 5 days out. It's rare to see a mean chart like this at that range, as usually the extremes are watered down by at least some of the members going off in another direction..

Pretty much all of the graphs are like this - virtually uniform..

The ECM treads a slightly different path, and the UKMO while closing in on the ECM and GFS still isn't there, so although you've got almost maximum confidence from the GFS on this one, we're not there yet..

[bluearmy]

'Warm' sectors showing within the cyclonic pattern. whilst they are not warm enough to be damaging to snow chances in dec/jan/feb I wonder if mid march can survive them? Ecm trending a little closer to gfs/gem and gfs trending closer to ecm in low res. Ukmo isolated at day 6 but will get there. Ecm is approx a day behind the ncep suite in timing.

[Ian Brown]

As Paul says, the GFS is bullish with the synoptic evolution. When it has been wrong earlier this winter, notably when rolling the Atlantic in, the climbdown tended to come when the contentious synoptics were around T96/108. So if it is going to switch towards the ECM or even the UKMO, then surely the changes have to come in subsequent output today.

[BLAST FROM THE PAST]

As Paul says, the GFS is bullish with the synoptic evolution. When it has been wrong earlier this winter, notably when rolling the Atlantic in, the climbdown tended to come when the contentious synoptics were around T96/108. So if it is going to switch towards the ECM or even the UKMO, then surely the changes have to come in subsequent output today.

Although Ian I think the ECM has brought the colder set up in quicker than it was showing hence edged towards the GFS line of thinking. Also the GFS now prolongs the cold and doesn't have a full on sinker. Today IMO there is even more consensus going forward with UKMO edging more towards them too. I would say that we're close to calling this one

BFTP

[Man With Beard]

Well, if you favour the highly scientific (!) method of 'halfway house', you'd have to say the ECM is most likely. GFS - extreme cold pushed south quickly; UKMO - cold stays mainly north, not that cold. Leaving ECM as the halfway house (well, slightly less than halfway to GFS)! Cold but not quite as extreme, but the cold stays in the UK for longer.

Edited March 6, 2013 by rjbw

[weather eater]

Leaving out the UKMO I would suggest from the 00z operational’s that the ECM has continued its early evolution backing of the GFS from last night, they are not the same but have the same theme, in the midterm plus the GFS appears to be leaning towards the ECM theme of last night and this morning. As often appears to be the case in these situations the models after an initial struggle to pick the early pattern then appear to flop about trying to work out where the evolution goes next. Given the broad similarities between the GFS and ECM up to 96hrs I would guess that the UKMO will fall into line this evening, or tomorrow morning at the latest however, while the GFS and ECM are not poles apart I would suggest it’s enough to say that uncertainty or FI is less than 72hrs at present and the UKMO has trumped them before, the January cold spell certainly.

[Radiating Dendrite]

Would we see snow showers for the east from the GFS then on Sunday/Monday given uppers of -14c?

We are looking at a 20c difference between sea and air temp, surely enough to get convection going??

[TEITS]

Would we see snow showers for the east from the GFS then on Sunday/Monday given uppers of -14c?

We are looking at a 20c difference between sea and air temp, surely enough to get convection going??

Must admit im struggling to figure out how much snowfall would result from this mornings GFS. I feel snow showers would be widespread pushing well inland but its the intensity im uncertain of due to the temps of the N Sea. If this output was being shown in Dec or early Jan then I would be predicting over 30cm in places.

[nick sussex]

Although the UKMO is a bit better for cold potential this morning it still disagrees with the ECM/GFS within just T48hrs , I don't ever remember this happening before.

I think the differences between the ECM and GFS later are just what happens in between the the reinforcement of blocking as the Alaskan ridge develops which triggers another pressure rise in the Arctic.

So I think its more how you hold onto the cold as that happens rather than will that reinforcement take place.

[Gibby]

Good morning. Here is the report of the 00z output from GFS, UKMO, GEM and ECM for today Wednesday March 6th 2013.

All models show Low pressure down to the SW of the UK with a slack SSE flow over the UK with occasional rain and cloudy conditions extending North and East to all areas. Temperatures will stay close to average over the coming days. Over the weekend as Low pressure generally inches in close to Southern Britain cold Easterly winds develop over the North and begin to extend South to other areas by the start of next week with rain turning to snow in the North.

GFS then shows a strong and cold NE flow over the South on Monday with rain turning to snow here too while drier conditions reach the North. These drier conditions extend South to other areas next week in association with High pressure slipping South just to the West of the UK through the week with frost developing again by night. Late in the week new Low pressure moving South to the North of the UK brings rain and sleet down into Northern Britain which through FI sweeps South and renews the surge of cold air from the North with spells of rain, sleet and snow over all areas to end the run in temperatures well below average.

The GFS Ensembles indicate the operational as a slightly colder option of the pack through the second half of the run. However, there is universal support for temperatures to fall off a cliff through the 10th as the cold Arctic air sweeps South to all of the UK. The general trend is for uppers to gradually recover to closer the seasonal average though there is plenty of spread between milder and colder options late in the run under unsettled conditions.

The Jet Stream shows the flow continuing to blow across Southern Europe well South of it's average. The flow does weaken in a weeks time and ridges North over the Atlantic just to the West of the UK.

UKMO early next week shows Low pressure moving slowly East along the English Channel with colder Easterly winds propagating slowly South from Scotland through the period. Largely cloudy skies will predominate with rain, especially in the South potentially turning to snow before drier air filters South from Scotland later.

GEM has Low pressure a little further South over france early next week moving away East. A cold NE flow with rain or sleet clears away as High pressure moves down from the NW later in the week. A few snow or sleet showers near Northern and Eastern coasts would be the exception to cold and bright conditions in light winds and sharp overnight frosts.

ECM shows cold and unsettled conditions next week with High pressure over Greenland and with deep cold air over Scandinavia Northerly or Northeasterly winds will pull this down over the UK with sleet and snow showers developing widely through the week with the chance of more persistent rain or snow later as Low pressure tracks East close to Southern Britain. Widespread unwelcome sharp night time frosts would occur again next week under these synoptics.

In Summary the weather will take a sharp turn colder early next week as High pressure over Greenland pulls very cold Arctic winds South over the UK. With Low pressure close by to the UK there looks to be plentiful opportunities for snowfall, more especially but not exclusively to Northern and Eastern Britain but maybe in the South and SW too should Low pressure close to the SW push troughs up into the cold air from the South. Frosts will be widespread and sharp so Gardeners beware the last few days of mild Spring weather was a false dawn and we will have to wait quite a while for anything remotely Springlike temperature wise looking at this morning's output and Jet Stream profile.

[Purga]

Although the UKMO is a bit better for cold potential this morning it still disagrees with the ECM/GFS within just T48hrs , I don't ever remember this happening before.

I think the differences between the ECM and GFS later are just what happens in between the the reinforcement of blocking as the Alaskan ridge develops which triggers another pressure rise in the Arctic.

So I think its more how you hold onto the cold as that happens rather than will that reinforcement take place.

The METO aren't giving any hints of any early arrival of cold and in fact all references to 'cold' are removed from the forecasts up to Sunday, only 'chilly'.

Outlook for Friday to Sunday:

Mostly cloudy with rain or drizzle at times, perhaps a few brighter spells. Temperatures near the average, but wind and rain making it feel rather chilly.

Updated: 0225 on Wed 6 Mar 2013

certainly squares with the RAW output this morning.

[Captain Shortwave]

The METO aren't giving any hints of any early arrival of cold and in fact all references to 'cold' are removed from the forecasts up to Sunday, only 'chilly'.

Outlook for Friday to Sunday:

Mostly cloudy with rain or drizzle at times, perhaps a few brighter spells. Temperatures near the average, but wind and rain making it feel rather chilly.

Updated: 0225 on Wed 6 Mar 2013

certainly squares with the RAW output this morning.

The metoffice yesterday were going for cold weather to be spreading south through Monday reaching all areas by Tuesday. This fit perfectly with the ECM and its ensembles. They still think GFS is far to quick.

Edited March 6, 2013 by Captain shortwave

[nick sussex]

The METO aren't giving any hints of any early arrival of cold and in fact all references to 'cold' are removed from the forecasts up to Sunday, only 'chilly'.

Outlook for Friday to Sunday:

Mostly cloudy with rain or drizzle at times, perhaps a few brighter spells. Temperatures near the average, but wind and rain making it feel rather chilly.

Updated: 0225 on Wed 6 Mar 2013

certainly squares with the RAW output this morning.

Yes its still a worry how its output is dragging its heels. But even it has the Alaskan ridge at 144hrs so the models are in agreement on the overall NH pattern.

[shedhead]

Given the overall performance of GFS across the past winter it perhaps not surprising that most are treating it's current offering with a fair degree of caution. However, it's probably worth remembering that we're now talking T+120hrs, not T+silly time and as Paul alluded to earlier the level of ENS agreement is staggering, perhaps even unprecidencted. Whether this will ultimately manifest itself as shown remains to be seen, but unless it comes up with a major volte-face across the next 2 or 3 runs I think the others will begin to fall increasingly in line with it's quicker evolution.

Edited March 6, 2013 by shedhead

[Purga]

The metoffice yesterday were going for cold weather to be spreading south through Monday reaching all areas by Tuesday. This fit perfectly with the ECM and its ensembles. They still think GFS is far to quick.

Thing is they were refering to a 'cold easterly or north easterly wind' developing in the same timeframe yesterday.

EDIT: relatively speaking Sleety it's delaying or the evolution in the SE which impacts on the whole country.

Edited March 6, 2013 by Purga

[stodge]

Morning all

Once again, some extraordinary synoptics on offer from the Operational output this morning,

http://www.wetterzentrale.de/pics/Rtavn11417.png

I'm sure the various synoptics have been posted ad nauseam so I thought I'd do something different. This would be an incredibly cold day for mid-March were this to be accurate.

http://www.dmi.dk/eng/index/forecasts.htm

Denmark goes from low teens today to ice days by the weekend.

http://www.wetterzentrale.de/pics/Recm1442.gif

Once again, an extraordinary chart for mid-March with the -10c upper well over England (albeit at night) so that would be a pretty sharp frost under clear skies.

UKMO, however, as others have said, remains far more reticent with the evolution at this time. Certainly, the weekend temperatures being offered this morning suggest nothing unusual.

[chris55]

The ECM De Blits ens are remarkable for the time of year with the mean hovering around the 0C line for the best part of a week, we even have the -20 scale on there!! If these conditions verify then I would not be surprised to see some March cold records broken in the UK.

http://www.knmi.nl/l...idth=692 class=

Edited March 6, 2013 by chris55

[Radiating Dendrite]

Another cracker coming from the 6z.

I am starting to get a little excited. Some serious cold for March!!

[Summer Sun]

Would I be right in saying the ensembles below never got that low during winter for what its showing on the 11th

t120 and 126 brrrrrr

You have to laugh folks wait all winter for this and it don't happen as soon as the coldies leave the forum and spring arrives bang it arrives in the height of winter this place would have been in melt down

Edited March 6, 2013 by Gavin.

[Radiating Dendrite]

Would I be right in saying the ensembles below never got that low during winter for what its showing on the 11th

Yep.

Pretty mental really! An average of -14 for the middle of March.

[Ian Brown]

06Z shows the perfect placement of where you need the core of heights at around T108 onwards.

Bitterly cold in strong winds with snow/ snow showers spreading well West.