General Model Output Discussion

[SMU]

Hi Steve

Regarding next week two questions, if for example the gfs 06hrs run verified in terms of night time lows possible under that slack flow am i ramping when i suggest -15 easily achievable in a prone location in England/ Wales with -20 for some parts of the Scottish Glens.

Also in terms of the sinking trough from Scandi is this preferable for it to sink not too far west? have been looking at the interaction between it and the low heading across Iberia.

Hi Nick-

Yes -15C easily achieved- I wouldnt be surprised to see close to -10 tonight....

As for the track of the low( the second one)- best route is down through scandi & down the North sea or slightly further East & it must clear the South coast & not stall out-

Further west or further north west limits the advection that gets west.--

As it stands the track on the ECM is perfect-

Just reread your post & you meant the first one- the track ideally as above as the northern flank pushes the cold air west- ideally somewhere south/se past dover into france- if it went sw then the surface flow on the northern flank would be SE & not great-

http://91.121.94.83/modeles/gfs/run/gfs-0-36.png?6

S

[nick sussex]

Hi Nick-

Yes -15C easily achieved- I wouldnt be surprised to see close to -10 tonight....

As for the track of the low( the second one)- best route is down through scandi & down the North sea or slightly further East & it must clear the South coast & not stall out-

Further west or further north west limits the advection that gets west.--

As it stands the track on the ECM is perfect-

Just reread your post & you meant the first one- the track ideally as above as the northern flank pushes the cold air west- ideally somewhere south/se past dover into france- if it went sw then the surface flow on the northern flank would be SE & not great-

http://91.121.94.83/modeles/gfs/run/gfs-0-36.png?6

S

Thanks no you had it right the first time , the Scandi trough which sinks south during next week and i agree the ecm here looks great for that. I think prospects for snow look very good for next week and suspect the main risk to slowly transfer from Scotland and northern England further south especially towards southern and se areas.

[Thundery wintry showers]

Just seen the ECMWF extended output which goes with the snowiest case scenario that I mentioned earlier- the high sticks around over the far north allowing a cold ENE flow and probable snow showers for eastern areas through to the end of the run. GFS also supports the same sort of idea.

It could still change at that kind of range but we certainly have a good deal of snow showers to come for many eastern parts up until at least the 7th January.

[Frosty.]

Thanks for that, in terms of comparisons of actual observed weather I doubt there would be minimal difference- baring a couple of degrees Celcius warmer-

It will put the UK infrastructure under strain if this develops,I think most densely populated areas can get along with on or 2 days of snowcover, however when are talking 5+ with subzero maxima things get a little shakey-

Anyway slighty off topic-

So all eyes towards the radar as well as 15:30 Pm-

Steve

tried to pm you steve but couldn't, anyway, happy new year.

[SMU]

tried to pm you steve but couldn't, anyway, happy new year.

email mate-in my profile

-GFS LOOKING better at 42-

you have the trough taking A slightly further westerly track allowing a light easterly feed over the northern flank-

http://91.121.94.83/modeles/gfs/run/gfsnh-0-42.png?12

that should feed snow to the home counties behind the trough at 36-

http://91.121.94.83/modeles/gfs/run/gfs-2-54.png?12

good timing for the trough at 06:00 am-

out to 66- significant upgrade on the PPN for the SE...

Steve

Edited January 1, 2010 by Steve Murr

[East Herts Snow]

Possible Thames/North Sea snow streamer developing between +60 and +66 hours.

Nb - Sorry Steve Murr, just noticed you had already pointed out that PPN has pepped up at +66 hours!

Edited January 1, 2010 by North Londoner

[Ocean Transit]

Come across these earlier which may be useful for model fans:

ECMWF Output (MSLP, 850s) - comes out quicker then WZ etc

http://www.meteogroup.co.uk/uk/home/weather/latest_model_forecasts/ecmwf.html

ECMWF *London* Ensembles (with GFS overlay):

http://www.meteogroup.co.uk/uk/home/weather/services/ensemble_forecast.html

GFS Model:

http://www.meteogroup.co.uk/uk/home/weather/latest_model_forecasts/gfs_ncep.html

Nice to see more ECM data reaching the net FREE

[karyo]

The 12z gfs is showing a streamer over northwest England for tomorrow! http://www.netweather.tv/index.cgi?action=nwdc;sess=

Temperatures will be marginal for the coast (say Merseyside) but further inland snow is possible. Then, in the latter part of the day, the trough is moving south bringing a spell of light/moderate snow with much colder air following behind.

Sunday also has snow flurries crossing the Pennines.

So yes, an upgrade for precipitation!

Karyo

[SMU]

I will be very excited to see the T 36 Fax later asits a dead cert for a Front moving south followed by a streamer type area of convergence over SE

S

[Osbourne One-Nil]

I tend to find when a trough is forecast for my area, it generally produces very little in the way of snow, but when showers are forecast for the NE, or nothing's forecast, we actually get our best falls. Today being a good example. So even if precipitation isn't forecast, don't abandon hope because on countless occasions, it comes along anyway.

Then again, I've had a few Winter Pimms, so I could be talking rubbish.

[Southender]

I will be very excited to see the T 36 Fax later asits a dead cert for a Front moving south followed by a streamer type area of convergence over SE

S

Rain to snow steve or all snow? Milder sector in there?

[Gerry]

Come across these earlier which may be useful for model fans:

ECMWF Output (MSLP, 850s) - comes out quicker then WZ etc

http://www.meteogroup.co.uk/uk/home/weather/latest_model_forecasts/ecmwf.html

ECMWF *London* Ensembles (with GFS overlay):

http://www.meteogroup.co.uk/uk/home/weather/services/ensemble_forecast.html

GFS Model:

http://www.meteogroup.co.uk/uk/home/weather/latest_model_forecasts/gfs_ncep.html

Nice to see more ECM data reaching the net FREE

Ahh you let my secret out of the bag whole of ecm is available in 3hr time slots from T0 - t240, precip, 850 500's to name but a few also on a vey local level such as the north sea for example: Have been using this resource on a professional level for quite some time shame KCC dont subscribe to them then they wouldn't have only ordered and budgeted for 22 days of road salt for the entire winter!! Things may well get quite interesting on kent non HA roads over the commng weeks

Edited January 1, 2010 by Gerry

[bluearmy]

Rain to snow steve or all snow? Milder sector in there?

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=ukuk&MODELL=nae&MODELLTYP=1&BASE=-&VAR=prty&HH=48&ZOOM=0&ARCHIV=0&WMO=

latest NAE shows this 'streamer' further se.

[SMU]

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=ukuk&MODELL=nae&MODELLTYP=1&BASE=-&VAR=prty&HH=48&ZOOM=0&ARCHIV=0&WMO=

latest NAE shows this 'streamer' further se.

definite snow on the northern flank- streamer subject to what angle the onshore flow sets up-

S

[bluearmy]

latest meto T120 with the discarded shard of the scandi trough (p/v) sat proudly over central england

its the weather eqivalent of 'three lions on the shirt ...........'

jet in the western atlantic looks favourable at t144 for preventing the sinker

Edited January 1, 2010 by bluearmy

[Iceni]

And, 1963 was a very dry and sunny winter; it was the persistent cold that allowed the snow to lie for so long, and not a succession of blizzards. I think that comparisons to 1981-82 (at least!) are quite fair, TBH...

This is true. Any snow which fell remained in situ and it ended up about 2'9" deep where I was living (West Sussex). As a child I could actually walk on the top frozen layer without sinking into it some mornings. Ice on lakes, was 1'6" deep and quite safe to skate on.

I'd like to see how cold it got, where can I find the records?

[NorthantsSnow]

Well the latest GFS isn't seeing this heavy snow event on Tuesday that the UKMO appear to be seeing. >20cm of snow in parts of Eastern England according to the UKMO but nothing of the sort showing on the latest GFS.

It's always slow to catchup with precipitation though so I'm not too concerned by this just yet.

[SMU]

http://91.121.94.83/modeles/gens/run/gens-21-1-54.png?12

PPN upgrades for the ensemble Mean-

thats very good news for the SE home county corner....

S

[Guest North Sea Snow Convection]

What do people think of the latest 12z UKMO - in reference to the t120 to t144 period. It doen't align as favourably as this mornings ECM to my eye, with the trough too far west, but I'm not sure how that would keep evolving ?

I'm not sure what to make of it.

[Methuselah]

This is true. Any snow which fell remained in situ and it ended up about 2'9" deep where I was living (West Sussex). As a child I could actually walk on the top frozen layer without sinking into it some mornings. Ice on lakes, was 1'6" deep and quite safe to skate on.

I'd like to see how cold it got, where can I find the records?

Mr Data is your man, Iceni...But, 1963's lowest temps were higher than both 1981-2 and late December 1995. I think??

Do you remember the freezing rain - the drops that froze onto the window panes??? And the sheen the snow had in the next day's sunshine???

[nick sussex]

What do people think of the latest 12z UKMO - in reference to the t120 to t144 period. It doen't align as favourably as this mornings ECM to my eye, with the trough too far west, but I'm not sure how that would keep evolving ?

I'm not sure what to make of it.

Hi Tamara well to me it looks like a dogs dinner although it keeps the high further north, it still looks wintry though but given its last few days verification stats i'd bin it! its currently keeping the no gaps model company!

[Methuselah]

What do people think of the latest 12z UKMO - in reference to the t120 to t144 period. It doen't align as favourably as this mornings ECM to my eye, with the trough too far west, but I'm not sure how that would keep evolving ?

I'm not sure what to make of it.

Just take it as it comes, T...It's one of those things that'll only resolve itself nearer the time. A bit like the sleet I've had today...Overall though, the synoptics look pretty good!

[Guest North Sea Snow Convection]

Hi Tamara well to me it looks like a dogs dinner although it keeps the high further north, it still looks wintry though but given its last few days verification stats i'd bin it! its currently keeping the no gaps model company!

ok nick - that sounds like a good enough answer to me!

Just take it as it comes, T...It's one of those things that'll only resolve itself nearer the time. A bit like the sleet I've had today...Overall though, the synoptics look pretty good!

I realise that, I was just enquiring about its sequence that was all. Nicks answer is fine

[Altostratus]

From the outputs I’ve seen so far this evening, it looks like an extended, very cold spell has begun. With the cold air established, there is bound to be a few surprise snowfalls – there nearly always is! The north and east are looking like the favourite spots, however, given the fact the entire country will have a deep pool of cold air in situ, coupled with a good deal of instability, snow could occur almost anywhere IMHO. All eyes to the radar over the next week or two.

The synoptic setup is such that the window of opportunity for snow is much longer than we’ve become accustomed to; hence, more places should receive snow than would usually be the case. I’m sure this will go down in history as a very memorable event. Indeed I think it already has for many.

Regarding the UKMO run, it isn’t entirely alone with that evolution. It looks like a another decent run to me however, with cold and snow aplenty. Looks like there could be a decent pressure rise over Scandi too.

I am heading back to Cairo on the 3rd Jan. I am gutted to be leaving just as the real fun and games begin - my first winter away from the UK and it looks like it will be a decent one.

Never mind, I look forward to reading everyone’s snow reports. Best of luck to everyone!

[nick sussex]

The GEFS ensembles for London upto 180hrs are nothing short of amazing,still waiting for the full set to appear but really over 180 hrs its the best i've ever seen.