Model Output Discussion

[tundra]

With the ECM again predicting the zonal winds to go neutral to maybe negative between 70 and 90 degrees north in the lower troposphere, it will be interesting to see if the ECM nwp model agrees this time or as a couple of days ago rejects the idea again.

Edited February 27, 2009 by tundra

[Frosty.]

I wouldn't base things on the met office 16 day. Remember they had to make a massive back track on the current mild spell , they were saying in the days leading up to it that it was going to get cold and then very cold , and in 2 days had backtracked to very mild.

Yes that was a stunningly embarresing backtrack.

Still major differences between the gfs & ecm regarding the track of next week's deep low, the meto must be following the gfs track because the ecm evolution does not tie in with the meto update today, it might tomorrow though.

[PB22]

Subtle changes in the GFS 12z output, with the low slightly further west on this run, and meandering around northern Scotland:

http://www.wzkarten.de/pics/Rtavn1141.html

http://www.wzkarten.de/pics/Rtavn1142.html

Lots of convection possibilities too - it looks like being a great spell of weather activity - blustery showers with hail, rain, sleet, snow and thunder all possible:

http://www.wzkarten.de/pics/Rtavn11411.html

[mountain shadow]

Tuesday night into Wednesday morning looking good for the white stuff particularly over higher ground in the north and west. Central belt of Scotland in line to.

GFS definetly trending towards METO with the low further north and west.

http://91.121.93.17/pics/Rtavn1201.png

[snowmadchrisuk]

Yes that was a stunningly embarresing backtrack.

Still major differences between the gfs & ecm regarding the track of next week's deep low, the meto must be following the gfs track because the ecm evolution does not tie in with the meto update today, it might tomorrow though.

Yes , looking like a north easterly feed of air is likely by the end of next week at the minute , but will it be cold enough is the question. But at least for the moment it is a better outlook than a south westerly would be. I would call this cool zoneality as I see it at the minute. Low pressure close or over the uk giving us a mixed bag. Not seen 12z yet so going to go and catch up now

[Yeti]

It's not often you see a chart like this is it:

http://www.wetterzentrale.de/pics/Rtavn1141.png

[Mr Frost]

Tuesday night into Wednesday morning looking good for the white stuff particularly over higher ground in the north and west. Central belt of Scotland in line to.

GFS definetly trending towards METO with the low further north and west.

http://91.121.93.17/pics/Rtavn1201.png

Totally agree my friend, i had taken 10 days off model watching. But what a great time to return! Looking very wintry around my area from + 75 to + 123 hours. Although throughout next week anywhere is at risk of thunder, snow, hail and maybe the odd waterspout or two off the coast! Fantastic, something to look forward to at last! I have barely seen any sunshine recently.

[mountain shadow]

Next week will be a shock to the system after the last two weeks nothingness.

Gale force northerlies, not cold enough uppers yet for proper lowland snow.

http://91.121.93.17/pics/Rtavn1441.png

[snowmadchrisuk]

12z is showing much more snow potential for tuesday night onwards. Temps lower at surface and 850 level. good run so far IMO

[londonsnow]

great end to the ski season for scottish resorts if the gfs were to be believed, albeit maybe too breezy and snowy to actually ski!

[snowmadchrisuk]

Look at the really cold air ready to dive south , stunning run and plenty of room for upgrades if we can just get the +114 chart into +72 i'll be very happy

Edited February 27, 2009 by snowmadchrisuk

[dice48]

look like there is going to be tons of snow on tuesdad night look at this!

[mountain shadow]

Out to T+168 and the Greenland surface high is taking on the big daddie Azores upper high.

http://91.121.93.17/pics/Rtavn1681.png

[snowmadchrisuk]

Out to T+168 and the Greenland surface high is taking on the big daddie Azores upper high.

http://91.121.93.17/pics/Rtavn1681.png

I think the azores will win on this run and build on top of us, but to far ahead to worry about that at the moment.

[Mark Parsons]

Out to T+168 and the Greenland surface high is taking on the big daddie Azores upper high.

http://91.121.93.17/pics/Rtavn1681.png

And if they were to join up then there would be fun...........

[mountain shadow]

Real battleground chart this. Very mild springlike air approaching ths south west, with bitter cold coming down from the north.

http://91.121.93.17/pics/Rtavn1922.png

[Cheese Rice]

If the GFS is right, there could be some extreme snowfall over the Pennines and other Northern hills next week:

http://www.wetterzentrale.de/pics/Rtavn1144.png

http://www.wetterzentrale.de/pics/Rtavn1141.png

A bit of a cold zonality setup really, which obviously is always good in terms of chances for northern blobe heading to the Dales next Sunday if the storm does track as per GFS, as conditions could be quite incredible over the hills

cking later (such as happened in January this year). Low level snow looks highly unlikely unless this blocking does develop perfectly, but with the storm taking a track like that, above 400-500m conditions could be absolutely horrendous with prolonged, driving snowfall giving blizzard conditions and drifting in the strong winds.

I will definitely

Too far out, but yeah the possiblity is there for heavy snow, but "extreme snowfall", depends what you class as exterme snowfall,i would say 5foot+ lying snow is extreme but i guess this is for UK standards.

Anyway many are very pesamistic as to wether snow will fall on lower ground, but how come the GFS are showing percip type to be snow http://gfs.netweather.tv/gfs.20090227/12/8...ctypeuktopo.png ?? Whenever GFS shows snow it is normally underplayed with it more snow to rain but that doesnt really happen. The GFS even shows snow right down to the south coast http://gfs.netweather.tv/gfs.20090227/12/1...ctypeuktopo.png ! So is the GFS not good at predicting snow?

[Mr Frost]

Well some great weather to look forward to next week, a wintry march bonus as i like to say!

At + 78 this is a great chart http://gfs.netweather.tv/gfs.20090227/12/78/h500slp.png and almost in to the reliable timeframe!

And this at + 108 is just fantastic http://gfs.netweather.tv/gfs.20090227/12/108/h500slp.png

Something for everyone to enjoy, although i would not like to be working outdoors.

[mountain shadow]

Azores High wins on this occasionm I would imagine a large diverenge on the ensembles.

I notice GP is on line, what do the tele-connections point to regarding the Azores High?

[Snowaddict]

Given the recent trends on the teleconnections coupled with the general mid term trends on NWP outputs, the threat of an easterly or northeasterly incursion during the coming month is growing IMO.

[NorthantsSnow]

The last frame of this run is my favourite, unfortunately it is also the least reliable.

Last run hinted at this though, could be a trend starting?

Yes, I want it to happen badly. Can you tell?

Edited February 27, 2009 by NorthantsSnow

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

Looking like it will be windy on Tuesday evening/night.

http://gfs.netweather.tv/gfs.20090227/12/102/ukwind.png

[Frosty.]

Out to T+168 and the Greenland surface high is taking on the big daddie Azores upper high.

http://91.121.93.17/pics/Rtavn1681.png

It looks a short lived cold snap on the GFS 12z, hp topples in with milder air early the following week but one step at a time. We will need to see what the ecm thinks because so far it's totally different for next week.

[Glacier Point]

Azores High wins on this occasionm I would imagine a large diverenge on the ensembles.

I notice GP is on line, what do the tele-connections point to regarding the Azores High?

With the GWO showing a quasi-stationary orbit in phase 2/3, we should be looking for:

1) cut off lows south of Newfoundland and blocking over the Canadian Maritime;

2) pressure to remain low across the UK and central / southern Europe with the ridge in the Atlantic transferring west and north.

The GFS idea of keeping the trough over Newfoundland intact t192+ looks suspect, at least as an prolonged idea of an Azores ridge as a result.

[Paul]

It looks a short lived cold snap on the GFS 12z, hp topples in with milder air early the following week but one step at a time. We will need to see what the ecm thinks because so far it's totally different for next week.

I wouldn't say it was completely different next week at all - yes there are subtle changes but nothing unexpected in that, particularly when we're talking about the tracking of a fairly large atlantic depression.

It's beyond 144 where there is some divergence from the 06z, but again at that range it's pretty typical and you can see the points at which it's happening.

You can follow the runs alongside eachother on the viewer (click prev on the right hand side of one of the drop downs to show the 06z), and you can see the slight variances up to 144, then the more defined differences appear, particularly in the modelling of the low pressure.

http://www.netweather.tv/index.cgi?action=nwdc;sess=