Model Output Discussion

[Thundery wintry showers]

I think thats a small improvement, but what we really want is for it to be further south, that may then allow for an easterly down the line

Maybe for snow lovers with a South East-centric perspective, but having the low further south, and not far east enough, opens up the possibility of warmer tropical maritime airmasses getting into the mix and coming around from the SE to give cloudy damp weather. If the low was to slide to the SE and bring in north-easterlies it would be another matter entirely, but this doesn't look very likely at the moment.

[mountain shadow]

Swings and roundaputs comes to mind with the 12Z.

Still the chance of snowfall but what the 12Z is showing in the medium range is far more promising than the 06Z.

Can't argue with that, but again the proper cold is in the medium term. Still not a run to be sniffed at. Need support from the other big two though.

[full_frontal_occlusion]

MJO I assume is rather like the NAO/AO in what it shows is not indicative of the weather it will bring but instead reflective of the changes in visual processed models (as such as we can see, and decipher).

I've always looked at the NAO and AO as being a represenatation of the deviation from the long term average or dominant pressure patterns.

As such significant deviations point to changes in large scale synoptics such as the dominant Atlantic vs blocking-highs etc.

ffO.

Edited February 11, 2010 by full_frontal_occlusion

[Duane S.]

Lets be honest the models don't have a clue what to do with this LP. Also how far S/E the Arctic HP moves is uncertain.

I'd certainly agree with that.

In fact I get the feeling we are on the cusp of some radical model swings yet again. The good news is that roaring Sou 'westerlies are not on the agenda! Yet.

[grab my graupel]

Maybe for snow lovers with a South East-centric perspective, but having the low further south, and not far east enough, opens up the possibility of warmer tropical maritime airmasses getting into the mix and coming around from the SE to give cloudy damp weather. If the low was to slide to the SE and bring in north-easterlies it would be another matter entirely, but this doesn't look very likely at the moment.

Hi Ian, Because this low isn't being driven by the Jetstream, as it would in a Zonal type setup, is that the reason the models might be struggling with the exact positioning?

I believe that cut off lows are notoriously difficult to model, so does the same apply

here?

[Iceberg]

Wow... The Snowy(mini Hurricane in FI), it brings 35-40cm a hr snow rates for parts of Ireland, We'ed spend the whole year digging the country out if that came about (not that it would), but.....

[mountain shadow]

GME has the trough about 500 miles further west than the GFS at the same point at t+132, models all over the shop.

http://www.wzkarten3.de/pics/Rgme1321.gif

Any METO yet?

[Iceberg]

METO is out to 96 on weatheronline.

It looks approx 100 miles or so west of GFS at that timeframe.

[locneverstop]

http://charts.netweather.tv/gfsimages/gfs.20100211/12/312/hgt500-1000.png

My favourite image Just imagine if that was the right side of marginal

Edited February 11, 2010 by locneverstop

[Geordiesnow]

It must be noted that the GFS 12Z is apparently the most over progressive run so it might have the low too far east just like on yesterdays run. However i would not mind if it carried on it trend of having the low further east as this would mean the UK will be in colder air.

A very unsettled output with little in the way of mild weather sums up the output imo.

[karyo]

METO is out to 96 on weatheronline.

It looks approx 100 miles or so west of GFS at that timeframe.

Link please?

[Thundery wintry showers]

Hi Ian, Because this low isn't being driven by the Jetstream, as it would in a Zonal type setup, is that the reason the models might be struggling with the exact positioning?

I believe that cut off lows are notoriously difficult to model, so does the same apply

here?

I think it's more to do with the handling of how far west the negative NAO is based. The further west the main thrust of the Greenland block, the further west that low is likely to go. It's similar to the vast uncertainty that arose over the late December outbreak.

[Iceberg]

Link please?

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=ukuk&MODELL=ukmo&MODELLTYP=1&BASE=201002111200&VAR=pslv&HH=96&ZOOM=0&ARCHIV=0&WMO=

[mountain shadow]

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=ukuk&MODELL=ukmo&MODELLTYP=1&BASE=201002111200&VAR=pslv&HH=96&ZOOM=0&ARCHIV=0&WMO=

Well, you can see even at that timeframe it isn't going the way of the GFS.

[grab my graupel]

I think it's more to do with the handling of how far west the negative NAO is based. The further west the main thrust of the Greenland block, the further west that low is likely to go. It's similar to the vast uncertainty that arose over the late December outbreak.

I'm with you, thanks for that

[mountain shadow]

Meto keeps the low to the south west so GFS ploughing its own furrough again. METO might start to pull into the continent again though as the Newfoundland low pumps up the Greenland High.

http://www.wzkarten3.de/pics/Rukm1441.gif

Although I suppose at that range not a lot of difference.

http://charts.netweather.tv/gfsimages/gfs.20100211/12/144/h500slp.png

Edited February 11, 2010 by mountain shadow

[cooling climate]

Lol I see the UKMO is showing what the 06z GFS run was showing this morning.

As I said earlier use a pin.

The model output certainly is compulsive viewing this winter.

[Geordiesnow]

I think the UKMO is a snowier run than the GFS but the problem will be, will there be PPN where the colder air is? Or is the low is too far West to pull its fronts to hit the colder air?

Interesting run though nonetheless but i think in terms of interesting weather, the GFS is better than the UKMO as the former has sunshine and showers written all over whilst the latter looks a more cloudier set up and if you are not under any snowfall, it will be dull to say the least.

[cooling climate]

I think it's more to do with the handling of how far west the negative NAO is based. The further west the main thrust of the Greenland block, the further west that low is likely to go. It's similar to the vast uncertainty that arose over the late December outbreak.

The modeling of the west based -NAO is becoming less and less as time goes on

with the Arctic high moving further south and east this is pulling the whole block

further east.

[Iceberg]

GEFS Mean run takes the low pretty similar to the control and ops runs. Meto approx 200 miles west.

Still they all agree on alot of snow.

[snowking]

A tiny bit of eastward correction it appears on the UKMO FAX at 72

http://www.meteociel.fr/ukmo/fax/fax72s.gif

Very tricky one to call this, unfortunately this is one of those situations where we certainly dont want any sort of blend of the models, which at present would result in LP moving straight down the spine of the country and mixing in milder air

This is going to go down to t+24 with the marginalities involved

SK

[Frosty.]

GEFS Mean run takes the low pretty similar to the control and ops runs. Meto approx 200 miles west.

Still they all agree on alot of snow.

Yes they do all agree on a lot of snow, whether you believe the gfs or ukmo it really makes no difference, next week looks cold and very unsettled with rain, sleet and snow every day from monday onwards with snow being more or less guaranteed in scotland throughout so it's further great news for the scottish skiing industry, have they ever had a better season than this in the last 20 years, I think not. Another very wintry meto update today so winter is far from finished with us yet!

[Snowyowl9]

A tiny bit of eastward correction it appears on the UKMO FAX at 72

http://www.meteociel.fr/ukmo/fax/fax72s.gif

Very tricky one to call this, unfortunately this is one of those situations where we certainly dont want any sort of blend of the models, which at present would result in LP moving straight down the spine of the country and mixing in milder air

This is going to go down to t+24 with the marginalities involved

SK

That a very strange looking fax chart,I havn`t seen nothing like it before.

The greenland high seems more persistant and not going out too far west,we`re still in cold.

http://www.wzkarten.de/pics/Rtavn2641.png

[J10]

GEFS Mean run takes the low pretty similar to the control and ops runs. Meto approx 200 miles west.

Still they all agree on alot of snow.

I tend to agree and that my comment yesterday about some people underestimating the snow potential for next week holds firm.

[Iceberg]

Whilst waiting for the ECM I was looking at the dynamics of the LP for Mon/Tue.

It really is as tight as it comes re forecasting.

Two charts below 20 hrs apart(showing 1000-850 thicknesses) the length of the mild spell for some is approx 20 hrs so not very large at all.

However notice the smaller sector of sub 130 over Scotland, this expands very quickly as it moves south and the heavy precip readily drags the lower, higher upper thickness and temps to the surface. This will be rapidly changing and if a forecast can get it right to within 50 miles they will be doing well. !