Model Output Discussion - 2nd March Onward

[Mair Snaw]

Is that a joke?

I wonder where they picked up that load of cobblers from!

No joke if you go to there web page and look at front page its in the bottom left corner......

[SomeLikeItHot]

All this discussion of racing makes me thing that someone should be running a book on when the cold comes -

GFS sunday :

ECM Monday

UKMO (apparently) tuesday.

Not at all:

Anyone going to offer odds?

[mushymanrob]

well, this cold now looks like a bullet i cannot dodge... and after years of weather watching this is now looking like it could be a record breaker, its fast approaching reliable. IF this expected spell is as severe as some models predict, we could well be re-writing the history books.

bugger.

[SomeLikeItHot]

well ive just seen the front page of the star and they have gone with "record warm march for uk"....... lets just hope the express gets wind of this and goes with it on its front page tomorrow, then we can relax knowing that the cold is nailed on.

Edit: sorry it actually says " HOTTEST MARCH EVER"

Lol. The tip of hottest march ever is from a person from brighton tourism. Yeah that's a good source!

[UV-RAY]

Back out of hibernation for what could be the best shot at cold and snow nationwide this winter, in spring. I think the GFS is being a tad too quick at bringing any deep cold to these shores but a cold/very cold outlook for the rest of this month looks the form horse.

[Thundery wintry showers]

Surely with the deep cold uppers and the warmer land due to the stronger sun, this is going to lead to some widespread convection and thus increase the risk of some quite hefty snow showers? Certainly more of a possibility than in January and February?

I think so, because of the colder 850hPa temperatures and the lower 500hPa heights and temperatures, which indicate deeper instability. The GFS precipitation outputs are indicating a fair amount of convection over the North Sea by both day and night, and some modest daytime convection inland too as a result of solar heating. The GFS is almost certainly over-egging the cold IMHO but the ECMWF evolution would also support some fairly potent snow showers.

After what's happened earlier in the season, though, I'm not going to feel too confident about this east/north-easterly shot unless it creeps to within T+72, especially given the much slower evolution that is consistently suggested by the UKMO.

If we do get this very cold blast, it probably won't break all-time records but it will be pretty exceptional for March in the context of recent years- I would certainly be interested to see if some parts of eastern England can manage maxima below freezing in sunshine (I recall that parts of eastern Scotland managed it on the 1st/2nd March 2001). I wouldn't be confident of it lasting for most of the rest of the month though- particularly as we head into spring, it is not uncommon for a very cold north to north-easterly type to be followed by a build of pressure to the south and a switch to warm south-westerlies or southerlies- and this can happen even with extensive northern blocking, if we get a slow-moving east Atlantic trough.

Edited March 6, 2013 by Thundery wintry showers

[Coast]

Just a gentle reminder to keep a bit more to the topic title please. With the current prospects on offer and the 12z runs out shortly, a lot of people will be viewing here over the next few days for model guidance and what you think the various outputs are indicating in terms of the weather

[Summer Sun]

After an exceptional cold start to next week GFS shows the cold easing as well progress through the week

Mondays highs

24 hours later we see the uppers rise slightly allowing the temperatures to get into positive territory again with 4 to 5c quite widely for England and wales

By Wednesday we see highs of 6 to 8c quite widely for England and wales as temperatures continue to recover

By Thursday we again see temperatures ranging from 6 to 8c for England and wales with any precipitation falling as rain away from the highest ground

The cold spell is looking short lived maybe 4 days max before temperatures recover to around 7c for many by wednesday

Edited March 6, 2013 by Gavin.

[Carlrg]

4 Days cold at best on the BOM then milder uppers returning.

http://www.meteociel.fr/modeles/bome_cartes.php?ech=6&code=0&carte=0&mode=1&archive=0

Atlantic coming back in at the end of this run.

http://www.meteociel.fr/modeles/bome_cartes.php?ech=6&code=0&carte=0&mode=0&archive=0

We are in for snow in the middle of this run with a mushy mess either side if the precip's are anything to go by.

http://www.meteociel.fr/modeles/bome_cartes.php?ech=6&code=0&carte=0&mode=2&archive=0

Looks like the wintry blast is going to be shortlived, only to be expected this late into the winter season.

Roll on the warmer spring weather and let nature get to work.

[johnholmes]

Having spent a little time comparing the models I suspect one or two of you are making the cold spell shorter than, on balance, it looks like being.

Of course it all depends on our individual take on each model and indeed which model may be nearest to the actual weather by this time next week and further on.

Predicting anything out of the skies beyond 96 probably 72 hours and further is a mugs game at best and when it is will it be snow or not an even bigger mugs game. So patience is required for this aspect. Try it at 48 hours out and do have a go with the guide to how to forecast snow (7 additional parameters above will it rain!). My own view is that the cold is, once it starts, late into the weekend perhaps extending south from northern Scotland, then as far as temperature levels are concerned, for this time in March, and using the Met O temperature guide, then 7 days is probably a good bet.

Edited March 6, 2013 by johnholmes

[Mucka]

TEITS the 1 or 2 c difference in gradient is much less significant compared with the instability of the air thats arriving-

sub 524 heights & towering cloud tops will produce heavy snow from the 00z & 06z run- big totals in the E & NE & parts of kent / Suffolk/ Norfolk if it all varifies.-

S

Absolutely.

I was quite dismissive of the snow amounts people were expecting from the last cold spell but this is a very different beast.

Rarely would I expect to see any decent snowfall in NW England with an Easterly but this could well deliver widespread snowfall with disruptive snow possible almost anywhere though obviously the East is better placed overall.

[Snowman.]

Yesterday

Today

You can clearly see the GFS is trying not to sink the High and extend the cold period.

I wouldn't go against this for it to continue doing so.

This chart many would bank.

and

Heavy snow everywhere!

Edited March 6, 2013 by SN0WM4N

[Frosty.]

Yesterday

Today

You can clearly see the GFS is trying not to sink the High and extend the cold period.

I wouldn't go against this for it to continue doing so.

This chart many would bank.

and

Heavy snow everywhere!

And it's probably still wrong, the high would have to end up further northwest towards greenland for the metoffice arctic spell to last a week, probably more like the ecm than the gfs.

[Carlrg]

TBH there's probably more chance of another significant meteorite strike than a FI map at 372 hours verifying. I agree though that would be exceptional snowfall.

[nick sussex]

Latest NAE develops the shortwave, so does the GME and the GFS.

Headline tonight could read UKMO humbled as shortwave drama puts the seal on a woeful week of modelling for the once star performer!

[Captain Shortwave]

More than likely.

I haven't backed that model since February and when the cold spell was shown I still backed the ECM.

GFS just a pile of poo.

I will give GFS one thing, it spotted the shortwave to the South of Greenland that all models seem to be agreeing on now miles before the other models. Which is the catalyst for the initial cold push.

UKMO T36

TA-DA

Edited March 6, 2013 by Captain shortwave

[nick sussex]

UKMO T36hrs humbling complete it develops the shortwave!

A sorry state of affairs for the UKMO this week wrong at T96hrs earlier in the weekend and wrong within T72hrs, very strange indeed to see it performing so badly at those timeframes.

Edited March 6, 2013 by nick sussex

[shaky]

UKMO T36hrs humbling complete it develops the shortwave!

forget one egg on ukmos face but lets throw a dozen off them😄

[Troubleatmill]

After an exceptional cold start to next week GFS shows the cold easing as well progress through the week

Mondays highs

24 hours later we see the uppers rise slightly allowing the temperatures to get into positive territory again with 4 to 5c quite widely for England and wales

By Wednesday we see highs of 6 to 8c quite widely for England and wales as temperatures continue to recover

By Thursday we again see temperatures ranging from 6 to 8c for England and wales with any precipitation falling as rain away from the highest ground

The cold spell is looking short lived maybe 4 days max before temperatures recover to around 7c for many by wednesday

W

Absolutely.

I was quite dismissive of the snow amounts people were expecting from the last cold spell but this is a very different beast.

Rarely would I expect to see any decent snowfall in NW England with an Easterly but this could well deliver widespread snowfall with disruptive snow possible almost anywhere though obviously the East is better placed overall.

Yep, with a disruptive flow & the suns strength, convective showers can pop up anywhere as we go into March, also as March 2006 showed us, any lying snow can stick around, i seem to recall lying snow for over a week even though it only fell one day and the rest was variable cloud.

[Summer Sun]

Its took its time but UKMO and GFS now agree with each other at t60

UKMO

Uppers for Saturday night

UKMO has had a rare blip this week compared to the cock-ups GFS has had in the past

Edited March 6, 2013 by Gavin.

[-uksnow-]

Well jolly good that the UKMO and GFS are finally in agreement - down to 60 hrs - is that a record for disagreement at only 2 and a half days away!? You can guarentee one thing now... ECM will go off the boil tonight!

[Thundery wintry showers]

The GFS seems to be programmed to model shortwaves more readily than the UKMO and ECMWF- as a result the GFS sometimes picks out shortwaves before the UKMO/ECMWF, but on the other hand the GFS is notorious for sometimes modelling too many shortwaves. I'm sure the GFS has had a fair number of cock-ups where lows were overdeepened somewhat, or phantom shortwaves modelled, within 3 days of the event, and sometimes with greater immediate relevance to the British Isles.

Thus I think some of the criticism of the UKMO model is over-the-top- it occasionally gets things very wrong at 3 days out but it is near the mark far more often than not.

It will be interesting to see whether the UKMO model picking up the shortwave at T+60 results in it modelling that cold east to north-easterly blast for Sunday/Monday.

Edited March 6, 2013 by Thundery wintry showers

[SMU]

The 12z GFS out to 84 is around 6 hours slower than the 06z so no issues there- however the low over the SW of the uk is further North which SHOULD hold the cold flow over the UK for longer & ensure the winds become more direct Easterly-

Can we get -15c over the UK on this run- which is usually very close to the hallowed 510 Thickness line....

All in all though pretty much identical- which means its game on....

Also big upgrade from the UKMO at 72-

http://www.meteociel.fr/ukmo/runs/2013030612/UW72-21.GIF?06-16

S

[Summer Sun]

UKMO at t72

GFS at the same time

Upgrade from UKMO as you were from GFS

Edited March 6, 2013 by Gavin.

[Summer Sun]

Full on beast from the east at t102

Cheltenham may need one of these next week

Of course we've been here before so caution is advised until its still showing at t72 and lower ideally

Edited March 6, 2013 by Gavin.