winter model output Winter Model Output Discussion -12Z 07/02/13 onwards

[Hammer]

I am somewhat bemused as to why people are getting all excited about what basically looks to me like a wet cold and raw few days of weather .Theres basically no cold uppers over us and anywhere south of at least the north midlands is just going to get rain? or am I missing something here?.

Read Ian F about the modified data suggesting risk of snow despite raw model output showing rain.

[Mr_Pessimistic]

I'm a bit new to all of this, but I'm finding it hard to see how anyone can get excited about what any of the models are showing at the moment due to the lack of cold 850's.. or am I missing something? Surely any surface cold will get modified by the relatively warm sea?

I am somewhat bemused as to why people are getting all excited about what basically looks to me like a wet cold and raw few days of weather .Theres basically no cold uppers over us and anywhere south of at least the north midlands is just going to get rain? or am I missing something here?.

I don't think we will get a reply, as the questions are a bit newbie-ish and everyones a bit excited about something?

[Snowman.]

Yet again the GFS just cant resist

18z

Trying to go under

12z wants over

Clearly we have no idea post T144 infact we have more a general idea of extreme FI than mid term I reckon we could see a few surprises next week.

[Mark Neal.]

With the 18z its a case of Short Term pain, for long term gain from an imby point of view, though some would still do well with snow come Monday. Although this won't be decided until right upto the event, how some are getting annoyed and anxious is beyond me, its going to be a nowcast, the snow-line will undoubted change for some it will be better, just enjoy the potential. February looking like it could be a cold month overall

Edited February 7, 2013 by Mark Neal.

[Nick F]

There's no way any model or fax drawn up tonight will nail the position of Sunday's low this far off, what's complicating matters IMO is it's a new low developing ahead of a shortwave upper trough sliding in from the west at the base of the upper trough extending down from Sern Greenland. The formation of new lows will never be handled with mesoscale accuracy this far off, no matter how powerful the supercomputer is. All we know is the low is likely to form somewhere just west of SW England or Wales then track somewhere across southern Britain, and within a range of a few 100 miles - which in our small little maritime island landmass can make a big difference to who sees snow and who doesn't!

Edited February 7, 2013 by Nick F

[Bristawl Si]

I think we will have to accept on this thread for the next few days, there will be a lot of IMBYism

To be honest, the best case scenario on a UK wide basis is for the LP further south, with a strong easterly flow on its northern flank. That way, we see the frontal snowfall Midlands southwards, followed by snow showers spreading from east to west further north....thats probably the dream scenario for the UK as a whole

Latest BBC graphics just tweeted by Ian F:

SK

Certainly doesnt look too shabby to me!

Not sure what people are expecting to be honest, considering the air hasnt been particularly cold.

This progged forecast seems half decent.

[Long haul to mild]

I don't think we will get a reply, as the questions are a bit newbie-ish and everyones a bit excited about something?

I am no expert, but I think that the colder uppers are not the be all and end all in this setup. We also have to consider dewpoints and the chance of evaporative cooling in heavier precipitation. It's all very marginal and could go either way but the noises coming out from the UKMO suggest that there still could be some interest ahead.

Also bear in mind that the GFS has not performed well recently and during the last cold spell often underplayed the snowfall on its ppn charts.

Hope that helps a bit.

[bluearmy]

I don't think we will get a reply, as the questions are a bit newbie-ish and everyones a bit excited about something?

There is more to snowfall than uppers. Its complex. Thats why at this range, we tend to leave it to the pros with their computers!

[Panayiotis]

I know it FI but undercut number 2, and oh WOW those uppers to the east should flood in...

[LomondSnowstorm]

The lack of a localised or long fetch maritime flow in the frontal zone is key in that lower dewpoints can be dragged westwards from the continent and turn initial rain to snow, provided we don't see any warmer layers aloft. Uppers needed for snow can vary hugely from just below 0C if cold is entrenched at the surface to -10C for coastal Aberdeenshire in a southeasterly.

[BLAST FROM THE PAST]

I think we will have to accept on this thread for the next few days, there will be a lot of IMBYism

To be honest, the best case scenario on a UK wide basis is for the LP further south, with a strong easterly flow on its northern flank. That way, we see the frontal snowfall Midlands southwards, followed by snow showers spreading from east to west further north....thats probably the dream scenario for the UK as a whole

Latest BBC graphics just tweeted by Ian F:

SK

This is where it gets interesting. Evene the S and SE will get pasted as it moves into the continent. However, BBC SE news weather girl having none of it. +4C and heavy rain....makes you wonder what the hell is going on?

BFTP

[cooling climate]

I am pretty sure that the 18z has the right idea with regards to the trough disruption

post t144 but wouldn't it be ironic waiting so long for robust Scandi heights that when we

get them the air to the east is not cold enough to support snowfall or laying snow and all

we see at lower elavations is rainy sleet and wet snow.

[Ryan Dutch Weatherman]

Nogaps 18z , still cold In britain at 144 .

High Pressure seems to me getting stronger by Navy model .

[Cheshire Freeze]

FI and we finally see the migrating high and dropping Scandi trough being hinted at. There is no better evolution for cold so late in the season (end of February)

[Panayiotis]

I said it before but the high over Scandi will be more stubborn than the models think/forecast to be, next week will be v.interesting as I see another undercut similar to one that we will have on Sunday/Monday.

[Cloud 10]

Nogaps 18z , still cold In britain at 144 .

High Pressure seems to me getting stronger by Navy model .

The NOGAPS = the new leviathan of model output...

[shaky]

Certainly doesnt look too shabby to me!

Not sure what people are expecting to be honest, considering the air hasnt been particularly cold.

This progged forecast seems half decent.

That is very similar to the ecmwf chart earliee this evening!!

[Don]

I am pretty sure that the 18z has the right idea with regards to the trough disruption

post t144 but wouldn't it be ironic waiting so long for robust Scandi heights that when we

get them the air to the east is not cold enough to support snowfall or laying snow and all

we see at lower elavations is rainy sleet and wet snow.

Indeed, just like the February 2005 event! Would still be good to get a strong Scandi high establish though.

Edited February 7, 2013 by Don

[Allseasons-Si]

Don'i know if anyone has posted these as of late but

nice to see some negativity there.

Edited February 7, 2013 by allseasons-si

[Jason M]

This is where it gets interesting. Evene the S and SE will get pasted as it moves into the continent. However, BBC SE news weather girl having none of it. +4C and heavy rain....makes you wonder what the hell is going on?

BFTP

I know where my money is

There is one variable that no computer is programmed to handle and thats 'murphys law'

Joking aside, Ian's update is very good news. It will change by the morning though, and again tommorow evening. The mid term is looking interesting still with a stronger and stronger Scandi high influence. I'd imagine pub run FI will be a great big outlier if prevoius ensemble suites are anything to go by.

Jason

Edit: How did the evil face get in the top left of this post. spooky

Edited February 7, 2013 by Jason M

[Ryan Dutch Weatherman]

CMA 12z finished now , the last chart.240 hours.

Cery cold for btittain with a strong easterly wind far over Ireland end the Atlantik.

Brittain lock down in a cold pool.

En btw look the colour canging by Greenland en East Canada.

[john pike]

[Cloud 10]

Hand's up who is waiting for the 96 and 120 hrs fax charts?

lol^^^

Edited February 7, 2013 by Cloud 10

[SMU]

Theres 2 ways of looking at tonight-

* 1) T72 sees a potential snowfall event heading in from the west & with minimal increments sw required to make it a widespread snowfall event,with sustained frontal snowfall-

Cold uppers then feed in from the East with the potential of snow showers & cold nights. After this, we have the potential to see some sort of undercut arriving from the NE with heights remaining high over scandi we could get locked into a cold spell from the east for some time. these tend to have a habit of upgrading nearer the time.

*2) T72 sees a low approaching from the west & the profile of the jet is about 20 degrees more east than originally progged so the low is going to sweep a bit further east -

The low is also deeper than first thought- which are the 2 key ingredients for rain instead of snow.

As the low is deep, even when it moves away SE the trailing cold air will be mixed with warmer uppers circulating around the low rather than the very cold uppers that were there a few days ago.

Post this once again a rather annoying shortwave develops over SW Norway which inhibits the retrogression

pattern & allows a low pressure to get east of iceland - & that sliding angle is a bit to steep for the UK.

After which we see a continental flow develop- however this flow is very slack with weak low anomalies over France, the upper air is also only just below freezing. Assuming we are approaching day 10 this is the 17th of feb. Winter is nearly over.

I think we are very much as a half full juncture now, you could be very optimistic or pessimistic about things depending on your vantage point, im going to sit on the fence & say my glass is 45% full, yes thats right- option 2 favoured as its been a gradual trending disapointment over the last 48 hours with a downgrade of the severity of every aspect of the cold & of course a slight hint of IMBY.

I would love to be able to swing back to those + 60's & 70%s however after looking at the ECM & studying the UKMO + ECM tonight whilst im not be silly & saying the atlantic will come roaring in it could be a case of a slow boat to the inevitable as opposed to all roads lead to rome.....

S

Edited February 7, 2013 by Steve Murr

[Ryan Dutch Weatherman]

Again support now from the 18z/00z/06z Cfs for a cold march 1e decade.