Spring Model Discussion 18Z 6/3/13 onwards....

[SomeLikeItHot]

I am struggling to see what down grades people are talking about except either in their minds or in FI? The initial 36 hours of extremely cold uppers (< -10 T80sseems to be more or less the same maybe a couple hours shorter but then longer lasting with -6 to -8 T850s for most of the UK? I think the snow progged by the GFS has changed but that was always likely.

[shaky]

Looks like the models are moving to a middle ground solution with the east/ne flow.

The UKMO a little better in terms of potential than last night and the ECM/GFS shortening it. Thereafter it still looks cold but you lose the coldest uppers so some marginality coming into the equation after that point.

The ECM looks like it could bring some very cold nights with that slack northerly, the inference after that is a change to milder conditions as energy runs over the top.

Also there might be some fronts moving south in that northerly flow , with a chance of some snow but this could be a wintry mix on lower ground.

It certainly looks interesting for the next week or so.

there are -8 850s on the ecm till 216 hours!'wont that be enough for all snow especially considering that its from a northerly source?

[Carlrg]

Not so epic run on the Bom. Looks like another nagging cold easterly with nothing too extreme showing IMO.

http://www.meteociel...ode=0&archive=0

Holds onto the colder uppers for longer than in earlier runs. But the really really cold uppers just don't quite make it.

http://www.meteociel...ode=1&archive=0

Slushfest !!!!!!!!

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

Winter is over.

Edited March 7, 2013 by Carlrg

[kent]

i really dont undestand how the ecm is a downgrade though!!its practically same as last night and also the ukmo is better aswell!'some of the comments on here sometimes amaze me!!

I agree, UKMO has only just fallen into line, GEM looking good. Unlike last time uppers are higher, air pressure lower. Still time for swings an roundabouts. Only thing thats certain is the uncertainty.

[Severe Siberian icy blast]

Yes I for one took the 12 z as todays 00z and I like the 00z better. Yes the UKMO has moved forward, but the GFS since yest, and ECM since yesterdays 00z have shortened the bitter blast [i think that is the crux that the deep bitter blast moves into France fairly quick]

BFTP

Indeed.

When I viewed the 0z and noticed ever so slightly the deep cold had been shortened , I could of predicted the mood by some this morning , I always expected a watered down version to be honest because it happens every single time, that doesn't meant to say its not going to be bitter on Monday with snow showers , because it will be. Then as we move further in the week we stil see cold northerly winds with 850's sub -5 , that will stil be cold , and could stil bring snow , with any disturbances in the flow , obviously amounts will be temporary given the sun , but we may stil see some surprises , but blizzard for 24hrs look unlikely , and always did because until you get within that 72hr range then things will always change , normally to a more tempored version .

Cold yes , snow yes , blizzards with 8inches ? No

[nick sussex]

there are -8 850s on the ecm till 216 hours!'wont that be enough for all snow especially considering that its from a northerly source?

If you look at the ECM it looks like it brings down some fronts with a less cold sector around 120 to 144hrs, before some colder upper air feeds south again.

So that could be snow, rain, snow, I think in terms of detail we're just going to have to wait till nearer the time but overall there is a good amount of interest.

As i said last night if people view this through March goggles and not as if its mid winter then they probably won't be too disappointed.

[weather eater]

Yep and that shouldn't be right in this day and age, we have seen this winter some very poor displays by some very powerful computer models....and I'm not talking t168+ either.

BFTP

Not really Fred, we live on a very small island events even at t72 are going to change and they don’t have to change much to affect us, the models will always stumble when it comes to the weather we receive in the UK. The problem is the same as it always is on these occasions, people understand the above all year round until it comes to cold and snow prospects and then the, if this run verifies posts start popping up, runs never verify on the scales needed for us, the broad brush strokes remain but small details keep evolving, often right down to the wire, we see it on every day of the year, that’s why Stella runs are always without fail useless at t120 plus, the vast bulk of the time of no use to us what so ever. I really find it difficult to comprehend how they are taken so seriously often by people who should know better. Given that its now March and we have an icy blast for a couple of days with possibilities of something more developing I can’t see much to complain about really, except by those that let their expectations run away with them.

Edited March 7, 2013 by weather eater

[Harsh Climate]

Sunday through to monday could be quite good with some exceptionally low uppers with some probably quite heavy snow in places. But after that away from northern scotland there probably won't be widespread settling snow down to low levels due to the milder sectors that will be imbedded in any features moving south in the northerly flow.

[Paul]

Those who want to insist on trying to ruin this thread with moaning, whining, bickering and point scoring you need to either self moderate yourself by stopping that sort of thing, or we're simply going to stop you posting in here.

There's the model mayhem thread if you want to moan (although what there is to moan about in the output this morning if you're a cold weather fan is beyond me), but even in there we'll not put up with bickering and back biting..

[Summer Sun]

Based on the 00z GFS run this cold spell looks like producing 2 very cold days (Sunday & Monday) after this temperatures slowly recover

Monday is another very cold day nation wide

Into Tuesday and temperature start to recover with highs of 7c for some 5c widely down the east snow fall will become increasingly confined to higher ground

On Thursday we again see highs of 5 to 7c widely

So in summary a 48 hour really cold spell is on the way after this we see temperatures slowly rise still below the seasonal average but it will become too warm for snowfall away from high ground and the far north of Scotland where it stays colder

FI has temps back where they should be

Edited March 7, 2013 by Gavin.

[Purga]

So, a quick shot of cold on Monday, moderating through the week with not much snow for most of the UK appears to be likely from most of the models.

Very dry cold ENS.

No notable frosts look likely either. Not bad but hardly spectacular unfortunately.

Edited March 7, 2013 by Purga

[Captain Shortwave]

Cold holding on a lot better on the 06z. -12 uppers still in the South East Tuesday morning

The -8 isotherm was clear of the UK by this time on the 00z run.

Edited March 7, 2013 by Captain shortwave

[snowmadchrisuk]

The 6z GFS has a much better flow on Monday , ISO Bars straight NE , Much better than the 00z run which had no long sea track on Monday.

[SMU]

Much better run from the GFS all be it the 06z, the key for sustaining the cold longer is the wave energy coming sw through scandi- the slower that it - the better it is-

The 06z has the -12c line over england for 36 hours- & more convective flow with lower heights.

Things like this are all or nothing events- If it all lines up right then the UKMO raw model & UK4 etc will be wrong with totals way over 2cm, if the flow is to fast from scandi then it will all be over in 24 hours & the UKMO call from Ian will be correct.

lets hope slow is the order of the day...

S

[Purga]

A few flurries - similar to the last easterly shot looks likely.

[SomeLikeItHot]

We will see. At the moment, "downgrades" are staying well withing the range of what the ensembles have been saying for the last day or so. If anything the cold for the period 13th to 17th of march has been upgrading if you look at the ensemble mean.

If you have believed the op run as the literal truth then maybe there is a scope for seeing this as a downgrade. If you look at the range the ensembles bracket around it then its just an expected variation.

Anyway onto the 6z which looks to be an upgrade for the Sth of the UK out to +120

[Frosty.]

I am struggling to see what down grades people are talking about except either in their minds or in FI? The initial 36 hours of extremely cold uppers (< -10 T80sseems to be more or less the same maybe a couple hours shorter but then longer lasting with -6 to -8 T850s for most of the UK? I think the snow progged by the GFS has changed but that was always likely.

I agree with you, when I logged on this morning and read about all the downgrades, I took a look at the models and saw the very cold initial blast is still there and that next week will be much colder than it should be approaching mid march.

[Purga]

Much better run from the GFS all be it the 06z, the key for sustaining the cold longer is the wave energy coming sw through scandi- the slower that it - the better it is-

The 06z has the -12c line over england for 36 hours- & more convective flow with lower heights.

Things like this are all or nothing events- If it all lines up right then the UKMO raw model & UK4 etc will be wrong with totals way over 2cm, if the flow is to fast from scandi then it will all be over in 24 hours & the UKMO call from Ian will be correct.

lets hope slow is the order of the day...

S

Trouble is Steve it's the 06z - but I hope you are right - I have a nasty feeling this will end up as a pretty dry albeit cold affair. I posted the ENS earlier backing up my thoughts.

cheers

[fergieweather]

Much better run from the GFS all be it the 06z, the key for sustaining the cold longer is the wave energy coming sw through scandi- the slower that it - the better it is-

The 06z has the -12c line over england for 36 hours- & more convective flow with lower heights.

Things like this are all or nothing events- If it all lines up right then the UKMO raw model & UK4 etc will be wrong with totals way over 2cm, if the flow is to fast from scandi then it will all be over in 24 hours & the UKMO call from Ian will be correct.

lets hope slow is the order of the day...

S!

Ah, but to clarify: I did say UK4 totals 2cm plus. For example, some spot-totals on high ground progged as 5-10cm. Moreover, no model can yet adequately resolve/synthesise possible localised focus through shower banding at this range. But not widespread amounts exceeding circa 2cm in either UK4 or EC snow distribution mapping.

[Geordiesnow]

No notable frosts look likely either. Not bad but hardly spectacular unfortunately.

Depends what you define by a noticetable frost, uppers are around -10 - -12 and if there is no noticetable frost this weekend and into Next week, I'll be shocked! So no idea what charts you are looking at Purga!

One thing to look for potentially next week is the large temperature differences between day and night time temperatures and look out for potential inland daytime convection to develop if the winds turn NNW'ly next week, if that happens, whilst the temperature may be around 5C in the sun, the temperature will drop close to freezing during any showers therefore likely to fall as snow!

[snowmadchrisuk]

What we have to be clear with though to be honest is when we are talking upgrade / downgrade we are looking for Snow, this is the only bonus a Cold Snap can have in mid march ... I'm looking at 2 main things for Sunday/Monday , 1) 850's below -10 and Iso bars showing a sea track right across the North Sea , because if them to ingredients come true with a gradient of over 20c between 850's and SST's in the North Sea , you will 100% get a Snow making shower machine in the North Sea , blowing Showers right across to the West into Wales, Banding is likely to be a feature with a Wash Streamer and also a one running into Kent.

[TEITS]

Trouble is Steve it's the 06z - but I hope you are right - I have a nasty feeling this will end up as a pretty dry albeit cold affair. I posted the ENS earlier backing up my thoughts.

cheers

Regardless that its the 06Z the models except the UKMO have consistently progged uppers around the -12C/13C mark.

The peak continues to be late Sun/Mon when min temps could drop as low as -10C in the far W. We also have a reasonable chance of snow showers becoming widespread and maybe even heavy across E areas.

http://www.wetterzentrale.de/pics/Rmgfs1204.gif

I feel what members need to take into account is having uppers below -13C for more than 48hrs is challenging for even the winter months let alone March. So if we take this into account then the model output continues to be extraordinary for the time of year.

[Yarmy]

Trouble is Steve it's the 06z - but I hope you are right - I have a nasty feeling this will end up as a pretty dry albeit cold affair. I posted the ENS earlier backing up my thoughts.

cheers

As has been demonstrated by the NOAA's own internal stats, there is a negligible performance difference between the 06z and the other GFS runs at T120. In fact for <T72 it is better than the 00z.

Of course, that's in general so I've no idea whether it is more accurate in this particular instance.

[SnowObsessor90]

So is another cold, dull and grey period looking to be the form horse then?, sigh....

Edited March 7, 2013 by SnowObsessor90

[Captain Shortwave]

No notable frosts look likely either. Not bad but hardly spectacular unfortunately.

The T2 temperature usually underdo minimum temperatures. Given the flow is polar orientated, the flow will offer a lot clearer weather than the previous one. Showers will vary depending on many factors but many inland areas will have quite a bit of sunshine and sharp frosts are likely. Probably not severe but will be notable considering the lack of frost we have had.