Rob K
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Posts posted by Rob K
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ecm soon i wonder what that has instore for us.
ECM out to 144 hours on Meteociel: http://www.meteociel.fr/modeles/ecmwf.php
Scandy high, easterly flow a little slacker than the 00Z run, but very cold air (510dam touching east coast)
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I have to disagree here the ukmo is perfectly fine ... The southern european low isnt going anywhere fast, the Atlantic trough is disrupting, the jet to the north is perfectly fine , the only thing thats sinking is your argument here!
OK well I'm quite happy to be wrong in that case!
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nowhere near as promising as the gfs, ecm & ukmo 00z which are full of potential.
I have to disagree about the UKMO 00Z - it's a much worse run than we've seen recently. It shows no sign of the all-important linkup to Scandinavia, so no long-fetch easterly. It's a sinker, pure and simple.
Compare UKMO: http://www.wzkarten.de/pics/Rukm1441.gif
to ECM: http://www.wzkarten.de/pics/Recm1441.gif
and look at the pressure over Scandinavia. Or scroll through the evolution here: http://www.meteociel.fr/modeles/ukmo2.php?carte=1021&ech=84
Worrying development, but only one model - let's hope it disappears on the 12Z!
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Thanks Ian,
Out of interest, on this picture from your blog:
what do those capital letters stand for over Wales?
(I'll have a guess here - is it something to do with the severity i.e. a letter further down the alphabet indicates more severe potential?)
Presumably standing in for figures above 9, so they fit in to a single space?
so A = 10, B = 11, C = 12 and so on?
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its not who is the best, but what is going to happen with this low in the coming few days. LP to far north. Warnings have now been reduced to possible advisories for north west england infact its quite a big back track there by the meto office.
This is off topic for this thread but you are totally wrong there. Currently there are warnings for Heavy Snow for the following areas:
Early Warning:
Blaenau Gwent
Caerphilly
Merthyr Tydfil
Monmouthshire
Powys
Rhondda Cynon Taff
Torfaen
Herefordshire
Shropshire
And advisories for:
The whole of the rest of Wales, plus
Derby
Derbyshire
Leicester
Leicestershire
Northants
Nottingham
Notts
Rutland
Bedfordshire
Luton
S Yorks
W Yorks
Blackburn
Blackpool
CHeshire
Gtr Manchester
Halton
Lancs
Merseyside
Warrington
Staffs
Stoke
Telford
W Midlands
Warwickshire
Worcs
Shropshire
Bucks
Oxfordshire
Milton Keynes
Bath & NE Somerset
Bristol
Gloucestershire
N Somerset
S Gloucestershire
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And at the other end of the country, some impressively low readings in Hampshire at 11pm, with -8C at Middle Wallop, -5C at Farnborough... and an unofficail -9C at Stratfield Mortimer up in Berkshire by 9pm.
Here in Yateley it's -5C too and the 7-8cm of snow cover has frozen rock solid.
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EDIT - uh-oh, -14.7C at 7pm...
I think there's some cloud moving in up there, which could start pushing the temperature up again. Not ideal still calm clear conditions tonight it seems.
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Tulloch Bridge -15.6ºC at 5pm. It was -11.4ºC at midday
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Bump... I see Topcliffe reached -13.3C at 7am, and may have gone lower between obs. -13.1C at 9am.
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Some of the nights minimums on this run are shocking. Either indicative that the new GFS model is too 'cold favoured' or that we may get a cold spell on the level of perhaps 1981. I just hope the models are having a fit.
The GFS minima aren't really suggesting 1981-style cold. Back then there were -20s and even -25s in central England. The lowest the GFS has gone for in England has been about -14C I think. A few days ago there was a rogue -21 over Scotland following this weekend's northerly.
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That 12Z GFS run is pretty remarkable. If I am correct, the gridpoint temperature for the far north of Scotland is at zero or below for EVERY SINGLE CHART from T+6 hours right out to T+384 hours, day and night. I don't think that has ever happened before....
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That will bring rain to the south I reckon, maybe snow on the chilterns - still a very mixed and messy synopsis though.
Yes - that fax chart is remarkable not really for the temperatures or weather it will produce as for the synoptics - a perfect semicircle of high pressure centres across the top with lows trapped below. Flip it upside down and you'd have a more usual winter chart!
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I was wondering that myself Paul, couldn't see this 5C drop between those timeframes.
By the way, it is possible to get those type of low minima with virtually no snow cover, -12C at Manchester Airport during late December 1995
And as I posted on the previous page, -11.9C at Chesham on January 7 this year. I recorded -10.5C in northeast Hampshire. There was no snow cover at the time.
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http://www.wetterzentrale.de/pics/Rtavn18017.png
I agree with TEITS- Uppers become irrelevent in this type of situation-
Slack air
Snow cover
Entrenched cold at the surface-
-13c in that frame-
& yes I doubt ive ever seen -15C in high res....
For people that are discounting these double-digit negative minima... remember we saw minima below -10C in southern England in January 2009 (at my local station, Farnborough, for one), and that was with no snow cover! I think the lowest recorded in that spell was -11.9C at Chesham, Bucks.
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Just to clear up, I'm perfectly capable of reading the colour codes, prehaps my wording wasnt the best
Mabe up to -15 would have been more appropiate.Apologies. But those charts were being posted a few days ago with people misreading the scale and claiming sub -15C uppers were on the way!
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I think you are interpreting that chart incorrectly. The darker blue you refer to denotes 850's between -10 and -15c, with the true -15c tied up miles to the north of UK. The lowest values indicated over the UK are about -10, perhaps -11c, but that's still very cold
and would see surface values at or below freezing IF they were to verify.Yes agreed, I posted a few days ago about people being unable to read a simple colour key on these charts!
BTW there has been a lot of nonsense spouted about the 850s being "downgraded". The GFS ensemble mean has NEVER shown -15C uppers over the UK. The coldest mean for London has been -9C, and that is still what is shown around the 19th. The upper air temps have been very consistent.
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http://www.wzkarten....cs/Rtavn001.png
Well it's coming out now ofcause no change YET
Well, for those that think the ECM is infallible, let's have a look at what its 168hr chart looked like... 168hrs ago (well, 174 actually)
Erm... look much like the current analysis chart to you, because it sure doesn't to me!
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Sorry to be really dim. What do the models show for us tonight? I have always read on here not to trust FI, but it seems in my little knowledge of weather that this cold spell is still in FI. Are we looking for trends, and what model should we now believe?
Well although all the real cold is in "FI", what is important is that the progression to a situation that will likely deliver that cold has now been firmed up and is shown at about 96 hours, which is pretty well within reliable range. (Touch wood!)
By 96 hours, high pressure is starting to ridge northwards starting the process of moving up to Greenland/Iceland or thereabouts (exact position subject to change).
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I would agree with your orig post snow , You were not 5c out on every count , I think you were spot on . Or you were to what them charts show.
Although just to add , them charts don't give you exact but if you can look on meteociel out to 168 and your first post wasn't far off.
No, he was wrong. Look at the scale.
From the right: red means 10 to 15C
Dark orange means 5 to 10C
Light orange means 0 to 5C
Yellow means -5 to 0C
Light blue means -10 to -5C
Next blue means -15 to -10C
and so on until dark blue means -25 to -20C
So the coldest air on the above chart is over Scotland and is between -5C and -10C (likely fairly close to -5C as it is close to the boundary with the yellow). The yellow air over England is between 0 and -5C.
The -5C isotherm closely follows the Scottish border, and also just clips East Anglia.
This can be confirmed by comparing with Meteociel: http://www.meteociel.fr/modeles/ecmwf/run/ECM0-168.GIF?08-0
That has -4C and -6C isotherms, not -5C, but the -6C covers NE Scotland only.
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Farnborough in Hampshire has recorded some of the coldest night-time temperatures in the UK over the past few days with several minima of -8C or below (-10C last night).
Here are a couple of pics from a rather cold Sunday bike ride...
Basingstoke Canal alongside Farnborough airfield. The swans had kept a little area free of ice, and there's also a heron there although rather hard to spot!:
The ice was pretty difficult to smash but I had to find out how thick it was... 4 inches, thicker in places:
And up on the heath there were some big puddles that were frozen solid enough to play around on with my bike... :blush:
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A low of -6C here in NE Hampshire and a very white frost. Farnborough a few miles away got down to -9C according to WeatherOnline. Those who were scoffing at the GFS temperature forecasts might have to be eating their words!
and would see surface values at or below freezing IF they were to verify.
General Model Output Discussion
in Spring Weather Discussion
Posted · Edited by Rob K
Say what? http://www.wzkarten.de/pics/Rtavn1622.png - from 12Z as I post, -10C over the whole of mainland UK! In high-res: http://www.wzkarten.de/pics/Rmgfs1622.gif -12s over many areas.
Will change as the 18Z rolls out though, but hopefully not much!
More snow around on the 18Z run... http://www.wzkarten.de/pics/Rtavn784.png