Winter Model Discussion 12Z 15/02/13 onwards.

[phil nw.]

Well we are now entering the final 2 weeks of official Winter and there`s still plenty of interest in the Model runs.

The current milder and benign conditions, likely to last into early next week, are expected to give way to some colder weather coming west from the developing Scandinavian high by T120hrs.

This will bring back widespread night frosts with daytime temps.falling back to low single figures.A chance of some snow flurries developing towards eastern districts with time as the cold air deepens,although at this stage any forecast of amounts are speculative.

The main interest then switches towards the end of next week as currently there looks to be a possible Atlantic attack from a developing low pressure to our south west.

The mean outputs for next Friday show this scenario

with the cold air already in place over the UK this could produce a snow event.

Of course at this stage details will change but the overall mean ht ens indicate a strong -NAO signal-probably the strongest of the Winter.

so plenty of signs for Winter to finish with a final flourish.

Ok then usual rules everyone-keep it polite and on topic.

There`s been some really good posts recently ,let`s keep it going.

Continue on below.

[fergieweather]

Just to note that UKMO give the GFS SW/S snowfall solution into next weekend only a 10% PROB so something akin to that evolution considered only a low likelihood for now.

[snowking]

Latest ECM32:

Reflects the Met Office update really for the remainder of February.

Latest ensembles for Birmingham from the 0z:

Cold for the foreseeable future

SK

Edited February 15, 2013 by snowking

[Average Joe]

Just to note that UKMO give the GFS SW/S snowfall solution into next weekend only a 10% PROB so something akin to that evolution considered only a low likelihood for now.

Oh blimey that won't stop them on here!! Apparently we have epic potential !!!

[phil nw.]

Just to note that UKMO give the GFS SW/S snowfall solution into next weekend only a 10% PROB so something akin to that evolution considered only a low likelihood for now.

Yes understand Ian.

A fair enough judgement at this range with placement and angle of surface developments far from settled.

It`s certainly a discussion point though -based on current MR 500hPa pattern.

[summer blizzard]

Not sure if people have missed this but for Leeds because its inland the GFS is suggesting that we could go 10 days with no precipitation (even then we are relying on a low resolution low)..

[fergieweather]

Yes understand Ian.

A fair enough judgement at this range with placement and angle of surface developments far from settled.

It`s certainly a discussion point though -based on current MR 500hPa pattern.

Absolutely. 12Z solutions awaited with interest.

[Cheshire Freeze]

Not sure if people have missed this but for Leeds because its inland the GFS is suggesting that we could go 10 days with no precipitation (even then we are relying on a low resolution low)..

You basing this on the GEFS ensembles? The ensembles which recently had decent agreement on mild uppers next week?

[offerman]

Thanks Ian,

It will be nice just to have some sunshine and to let flood affected areas dry out!!

[Summer Sun]

Just so people know the NOGAPS model will be retired on March 13th and will be replaced by NAVGEM which is in operation now here only the 00z and 12z runs go to 180h 06z and 18z run to 144h only

NAVGEM brings in some cold -8 uppers to the SE at the end of next week based on the 06z run

Edited February 15, 2013 by Gavin.

[summer blizzard]

You basing this on the GEFS ensembles? The ensembles which recently had decent agreement on mild uppers next week?

No, the last dozen operationals.

[Sunny_AS]

The models must truly be on to something significant if it has made both mushymanrob and WIB to come back and post on here!

[bluearmy]

I am intrigued as to why NOGAPS has suddenly become valued on here. until we see some verification stats for NAVGEM, can we leave it where it always used to be left ......................................

eyes down for the 12z's then. how close can we get the upper cold pool from our east (questionable). how close can we get the instability to our sw end next week (less questionable). the upper cold pool would be a great ending to winter but alas, i fear this has now drifted away with only a poor relation coming at a later juncture now the option.

[Tamara]

Oh blimey that won't stop them on here!! Apparently we have epic potential !!!

The thing is, with it being a week and a little more away, there is plenty of time for fine tuning. And this fine tuning might yet be favourable for us critters

And before then there are possibilities too - for some of us

Edited February 15, 2013 by Tamara Road

[Met4Cast]

I am intrigued as to why NOGAPS has suddenly become valued on here. until we see some verification stats for NAVGEM, can we leave it where it always used to be left ......................................

From what I could make out of Ians posts yesterday, NAVGEM is rated by the MO currently over the GFS - The fact it's one of the first operational models to take into account Stratospheric temperatures, I think we need to keep an eye on it

Edited February 15, 2013 by Daniel Smith

[Harsh Climate]

I see 3 options on the table for next week:

1. Light easterly airflow but dry under high pressure

2.Cold east/south easterly flow becoming bitterly cold with snow showers to the east becoming heavier and more frequent

3. The most likely IMO, Cold east/south east airflow but mainly dry apart from a few wintry showers in the east and small risk of snow in west/southwest.

Nice synoptics we are seeing and there is certainly potential but I seriously doubt we are going to get deep cold/snowy weather from the east just yet.

There is no real core of deep cold over europe/russia at the moment so we would be reliant of a reload of some sorts. I hear people mentioning a sausage shape high??? Until we get deep cold into that air source we would tap into, it doesn't matter how great the synoptics are! Lets firstly get a good block in place, then secondly a cold shot of air into europe.. Then we can dare to dream

[SMU]

gfs coiled like a snake at 84 ready to unwind the viper

[Tamara]

lol! My sentiments entirely..... Lets hope we get bitten

Not long now till the UKMO comes out - hopefully a better profile for upper cold than this morning

Edited February 15, 2013 by Tamara Road

[Methuselah]

lol! My sentiments entirely..... Lets hope we get bitten

Not long now till the UKMO comes out - hopefully a better profile for upper cold than this morning

Or have to endure a series of annoying little nibbles?

[PB22]

Little change on the 12z GFS so far...I remember not so long ago a chart like this would have the forum in meltdown:

[cooling climate]

When you look back through the archives and also from what I can remember from past

experiences all easterlies are different there is no set pattern of we have to have this,this

and this to get to this.

In this present situation though to get the cold uppers to the east to back west we will need to

see some trough disruption in the Atlantic with some energy running to the south of the UK

pulling the colder uppers westwards. Its as simple as that really.

One cautionary note is that any laying snow with temps of 2c by day during the second half of

February will not last long during daylight hours as posters who remember the 2005 easterly

will verify.

[LomondSnowstorm]

The upper cold pool looks slightly stronger on this run with -8C uppers again widely across Britain. Certainly that would be likely to give more of a sunshine and snow showers setup if it verified with accumulations, at least overnight, for eastern into central areas (though the flow remains fairly slack at this stage).

[Tom Jarvis]

Is the ukmo stuck at 60hrs??

[shaky]

No comments on the ukmo??

[Ian Brown]

When you look back through the archives and also from what I can remember from past

experiences all easterlies are different there is no set pattern of we have to have this,this

and this to get to this.

In this present situation though to get the cold uppers to the east to back west we will need to

see some trough disruption in the Atlantic with some energy running to the south of the UK

pulling the colder uppers westwards. Its as simple as that really.

One cautionary note is that any laying snow with temps of 2c by day during the second half of

February will not last long during daylight hours as posters who remember the 2005 easterly

will verify.

That Feb 2005 was a one off, Europe had become so warm during the previous weeks that it really diluted some great synoptics.

Subtle changes from the GFS and here comes the air mass battle, block in a good place though.