Model Output Discussion - 2nd March Onward

[TEITS]

As 'incredible' as the ensembles undoubtedly are, this morning, how many times do the ultra-extreme solutions ever verify? The very word 'incredible' implies a certain unlikeliness?

Well if you think I joined this forum in 2004 then only 2 or 3 times have I seen these verify i.e 2009,2010. Pretty much says it all.

However we don't need to see the mega cold -15C runs to deliver the goods though!

EPIC!

Such a shame the N Sea is so cold. If this was Dec then E areas would be digging themselves out!

Edited March 5, 2013 by THE EYE IN THE SKY

[Yarmy]

As 'incredible' as the ensembles undoubtedly are, this morning, how many times do the ultra-extreme solutions ever verify? The very word 'incredible' implies a certain unlikeliness?

I suppose if one averaged *all* the models then the GFS would be two or more standard deviations from the mean and so probably has a less than 20% chance of verifying. But, for me, part of the fun of this thread is seeing the extreme synoptics and knowing that it is physically plausible even though unlikely to happen. (I actually have an interest in this not coming off given I will be trudging around Elveden Centerparcs with a 4-year old and 1-year old at the weekend)

[Weathizard]

North/North East will again be pummelled by snow showers from this, that chart is a really beauty! If only it was in december/January, its like winters trying to wind us up by coming back when quite a few want Spring.

144 pretty good for other areas too.

Edited March 5, 2013 by Weathizard

[Liam J]

Sub -12c 850's a bit further west on the 6z, could be some very cold spring lambs in the fields!

Quite an impressive chart for the time year.

[SomeLikeItHot]

So while we are discussing the incredible GFS mean, does anyone else have the opinion that the GFS ensembles are too narrow in the range of outcomes they project? We saw before the late feb cold spell that 5 or 6 days out they were all against it, while the ECM op and majority ensembles were pointing to it. While the ECM op has flopped around in the last few days, it seems to me that it has always had a cluster of cold members, probably 50% or greater.

Indeed it seems poor modelling for the GFS, which we know to be statistically slightly worse than the ECM and UKMO, to not even be able to find a single member greater than -8 T850 for London around the evening of the 11th, while the ECM op is suggesting something more like -2 T850 (just reading off the chart).

A lack of cold members in the GFS ensembles implies something like a only 5% chance of something warmer than -8c T850, surely its greater than that.

[Captain Shortwave]

T144, all of England under -12 to -14 uppers. What can you say about that.

[TEITS]

Ha ha a drop of 13C in upper temps in 12hrs on Sunday if the GFS is right.

http://www.wetterzentrale.de/pics/Rmgfs1322.gif

Dewpoints would also drop by around 10C.

Plausible though and I have experienced this before in the 1980s.

[nick sussex]

As good as the GFS might be in the early stages the Azores high is a problem because that will drag the high to the north further south.

I think a shortwave is going to be needed in this instance a good one not spoiler to cut under the block. I haven't checked through all the GEFS but it would be good to see some with that evolution.

[SomeLikeItHot]

Hmm the 6z brings -14 T850s into the north of England at 144 hrs.

Can the 12Z make it to -16?

Edited March 5, 2013 by SomeLikeItHot

[Coast]

As we are highlighting GFS, I posted the latest London free-atmosphere chart in our regional earlier, makes interesting reading and thoughts for upper level temps and 500-1000 thicknesses from Sunday morning onwards.....

Edited March 5, 2013 by Coast

[SMU]

http://www.wetterzentrale.de/pics/Rmgfs1472.gif

Good plausable consistency from the GFS-- now dropping the uppers to -14c with -15c just off the coast.

It would be nice if we could hold that strong unstable flow for longer- but in the GFS eyes a 24/36 hour window for snow-

S

[Liam J]

Well it certainly wouldn't be feeling spring like! Could be some of the coldest nights of the year.

[shaky]

Hi peeeps!!!am baaaaaack!!wife just gave birth to a baby boy so been busy!!my word ive just taken a look at the models and if they are to be believed we are probably heading for the coldest weather we have seen in the last 3 months or so!!how the heck do you get 850s of -14 in march!!enjoy what we got right now cos wer about to head back into the freezer rapidly ðŸ˜!!

[Derecho]

As good as the GFS might be in the early stages the Azores high is a problem because that will drag the high to the north further south.

I think a shortwave is going to be needed in this instance a good one not spoiler to cut under the block. I haven't checked through all the GEFS but it would be good to see some with that evolution.

Yup however I think the chances of such an occurence are still reasonable, the surge of -10C uppers to the west of Ireland has a fair chance of causing a decent amount of instability in the Atlantic which could allow the required disturbances to form...

Also at this range the output won't pick up the unstable flow. -12C to -14C uppers over the England in March would cause a fair bit of instability to say the least!

Looks good for a widespread area of the UK however those in the SE and East Anglia especially would see frequent very heavy snow showers if this came off because the high is a bit further North this time then the late February cold spell.

If the Azores high is kept further back we could end up with something spectacular.

I also think GFS may be get this one right as the weather pattern over the US at the moment is conductive to a noticeably negative NAO, especially with such sharp cold anomalies over Florida and even sharper positive anomalies over NE Canada, reminiscent of the pattern over the US during Jan, Feb and Dec 2010.... the Atlantic SST anomalies look pretty favourable also. You know something is potentially brewing when the 06Z shows -14C just a week away and when you consider the fact it's usually a progressive run...

Question is how close will the high pressure be? hopefully further away then February so we get some really good instability in the flow.

Edited March 5, 2013 by Quicksilver1989

[weather eater]

As good as the GFS might be in the early stages the Azores high is a problem because that will drag the high to the north further south.

I think a shortwave is going to be needed in this instance a good one not spoiler to cut under the block. I haven't checked through all the GEFS but it would be good to see some with that evolution.

Indeed and yet again we seem unable to get a proper GH, not for the first time this year.

[No Balls Like Snow Balls]

The GFS is certainly very impressive in the mid term upto (T144). The evolution to cold starts as early as T72 on the GFS with pressure rising between Iceland and Greenland at this time frame.

[nick sussex]

It really is quite a confused picture because the ECM has the high holding further north and that looks more likely to extend the cold but it takes alot longer to bring that in.

The GFS is quickest and least fraught in terms of what could go wrong if you want to see some cold and snow but any cold would probably be shorter.

In terms of 850's these are really quite incredible for this late into the year.

[shaky]

It really is quite a confused picture because the ECM has the high holding further north and that looks more likely to extend the cold but it takes alot longer to bring that in.

The GFS is quickest and least fraught in terms of what could go wrong if you want to see some cold and snow but any cold would probably be shorter.

In terms of 850's these are really quite incredible for this late into the year.

middle ground maybe??cold spell wont be too short or too long which would be good!

[snowking]

A lot of people getting carried away with the GFS this morning, and understandably so - we can all hope and pray it comes off

However, I continue to urge caution. How many times in recent weeks have we seen the GFS offer a different solution to the UKMO/ECM all the way up to +96, before backing down.

The form horse from the ensemble mean heights remains a cyclonic NEly flow, however the depth of the 850 pool that gets advected to the UK remains hugely variable, and given the setup (and high risk of a scuppering shortwave pattern) I would be placing more faith in the higher resolution operationals at this juncture than the ensembles, which tend to be a little slow to react (remembering that the ECM/UKMO offer a higher resolution than the GFS)

I do not recall too many examples of the ECMWF/UKMO failing against the GFS - December being the best example of such a scenario (people keep mentioning 2010 and they may be right - but I have yet to see anyone post archive charts to back this up).

Best to keep a level head on things until we get into the +72 timeframe in terms of the upper cold pool and the strength of any easterly flow - particularly when you take a look at the ECM postage stamps this morning, plenty of room in those for both significant upgrades and downgrades of any potential cold

So colder - yes. Snowy? It will be some days before we know yet.

SK

Edited March 5, 2013 by snowking

[weather eater]

Indeed and yet again we seem unable to get a proper GH, not for the first time this year.

ECM much better in this regard but given its performance in regards GHs this year it doesn’t fill me with confidence.

SK re 2010 trust me or go look for yourself the evidence is there. i posted the links earlier.

Edited March 5, 2013 by weather eater

[Frosty.]

I don't know how many will agree with me but I would much rather have the Ecm 00z than the Gfs 06z, the 6z cold is significant but the block soon collapses and flattens out whereas the ecm is setting up a more prolonged very cold spell and not just a few days cold snap then gone, so hopefully the ecm longer cold spell will develop, keep that high much further northwest rather than toppling southeast. Looking forward to the meto update.

Just take a look at T+192, the 6z shows the games up, the ecm is going strong with power to add.

Edited March 5, 2013 by Frosty039

[snowmadchrisuk]

This isn't anything like DEC 2010 , For example most of the Snow in DEC 2010 came from Atlantic lows pushing up from the SW , as for this current setup I wouldn't be surprised to see the SW miss out on any wintry weather totally ... (Yet Again) .

[MR EXTREMES]

nearly fell off my chair when i looked at the models this morning absolutely mental europe could well have the coldest spell of weather of all winter season could turn out record breaking even the uk could catch some of this ive not seen uppers like this for a longtime incredible but im still staying on the fence as i have for nearly 4 months.

totally barmy the arctic must be seeing record lows aswell.

this goes to show that its worth taking into acount the strats lagtime

I don't know how many will agree with me but I would much rather have the Ecm 00z than the Gfs 06z, the 6z cold is significant but the block soon collapses and flattens out whereas the ecm is setting up a more prolonged very cold spell and not just a few days cold snap then gone, so hopefully the ecm longer cold spell will develop, keep that high much further northwest rather than toppling southeast. Looking forward to the meto update.

Just take a look at T+192, the 6z shows the games up, the ecm is going strong with power to add.

dont care if this happens then i think most of the uk will see something very special for march even 63 would blush.

[Methuselah]

Ha ha a drop of 13C in upper temps in 12hrs on Sunday if the GFS is right.

http://www.wetterzen...s/Rmgfs1322.gif

Dewpoints would also drop by around 10C.

Plausible though and I have experienced this before in the 1980s.

I think we might just about feel a drop like that, Dave?

[CWT2012]

The only certainties are that it is going to be very cold (nailed on) and that areas particularly to the east are going to see very heavy snow showers (nailed on), it is all about the finer details now, length of the cold snowy snap and the intensity of the snow, all 3 of the big guns support the extremely cold and snowy weather but are just not agreed on timing and length of the spell and its severity.

But we are on the brink of something quite special for March