Model Output General Discussion

[paul tall]

Yes Shawbury during the 12-13th Dec. The temp dropped to -25C and was already -22C at 6pm on the 12th.

Here are the charts.

http://www.wetterzentrale.de/archive/ra/1981/Rrea00119811213.gif

http://www.wetterzentrale.de/archive/ra/1981/Rrea00219811213.gif

Wasn't it the following month Jan 82 when Newport dropped to -26? There was a few -20 nights during December 81 and January 82. It was a remarkable cold spell made even more remarkable by the fact that after the mild interlude, equally severe cold reloaded in January! It was the 1979 snow and the 81/82 cold that sparked my interest in the weather, particularly extremes.

[Upgrade]

I think after looking at the 18z GFS you just couldn't get anything better. Its got everything that you could

ask for and would rank alongside any of the archive freeze ups, incredible run.

What the models are showing I think is once the very cold weather becomes imbedded over the weekend

and into next week the weather pattern will default to cold rather like when you are in the middle of a mild

or very mild spell the mild always seems to be the default pattern.

I hope that makes sense.

It looks like the models are trying to resolve this. In the 80's sometimes easterlys were well known for setting in for weeks once they took hold in winter. horribly cold. Of course we didnt have computer models to look at then. These runs are truly fascinating.

[Weather-history]

Stephen, it is -3 at 1200 on 22/12, -4 at 1500 on 22/12 and -15 at 0600 on 23/12 using the Pennines as an example. Where is the 4-5c drop between 12 and 1500? And over a snowfield in the right conditions is it that implausible for an afternoon temperature of -4 to drop to -15?

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

[Guest]

I am sorry but the temperature shown by the GFS are nothing short of ridiculous, there must be a glitch in the system, because there is no way the temperature would drop 4-5C from 12pm to 3pm, and then drop severely to -15C overnight. It's verging on climatically impossible for an island in the Atlantic!

It will have changed by tomorrow, but some shockingly bizarre specific output by the GFS. If there ever was a true pub run, it's this one.

The 06Z was showing mins of -20C over Scotland this morning for the weekend, does that make it the hangover run???

Sorry Ste, but if there is any snowfall across Scotland this weekend then temps will fall very very low very quickly. I know many will say there are major differences but the similarities between this set-up and 95 are too seductive to ignore. Fair enough that further south may not see such low temps, but it is all there for certain spots in Scotland. And before you point it out, I know you're looking at one overnight period, but as an extended outlook, these very low mins may well happen.

[Nick F]

Its not the figures I'm discounting as such, it's the areas there forecast to, and the way the temperature are changing.

For the temperature to be -2C at 12pm (fair enough), but then to drop to -5C by 3pm, anyone with experience in climate physics will know that on an island which is predominantly affected by the Atlantic ocean, this just doesn't happen!

If you think it's going to happen, good luck to you!

Well inland and sheltered by mountains to the west such as in W Midlands, English/Welsh Borders and in a stagnant or slack cold airmass - quite possible. The influence from the Atlantic would be fairly minimal with little wind flow.

Unusual synoptics evolving over coming days, which will really put the NWP to the test, and expect some rather low temps inland where winds fall light and there's snow cover.

[londonsnow]

Wasn't it the following month Jan 82 when Newport dropped to -26? There was a few -20 nights during December 81 and January 82. It was a remarkable cold spell made even more remarkable by the fact that after the mild interlude, equally severe cold reloaded in January! It was the 1979 snow and the 81/82 cold that sparked my interest in the weather, particularly extremes.

yeah i recorded -23 that year in rural oxfordshire. so cold going to school my nose froze

[Nick B]

Sorry Steve I think you are overeacting to the GFS output- IF the Synoptics varify as is then -15c is more than likely going to be smashed-

Newport in shropshire reached -26c in Jan 1982- I AM sure the GFS would have gone for a -15/-20 in that area on the high res model the day before..

we are just not used to these synoptics & reloads in the most recent past-

as regards your timings comments- Maybe 3-4pm.......

S

Agree. I for one remember going out on a paper round in the 80's just after catching the BBC telling me it was -17 deg C in my area. It has happened before and these synoptics are more than capable of producing real bone-chilling cold, especially over snowfields.

[January Snowstorm]

Latest fax out for Sunday has a front just clearing to our South after giving practically everywhere several hours of snow.

Heaven has come to earth!!

[SP1986]

I'll see it when I believe it.. until then I remain massively sceptical!

I've never, myself, seen temperatures that low on the models (I didnt see the 12z though)

[Rob K]

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.

[casparjack]

Sorry Steve I think you are overeacting to the GFS output- IF the Synoptics varify as is then -15c is more than likely going to be smashed-

Newport in shropshire reached -26c in Jan 1982- I AM sure the GFS would have gone for a -15/-20 in that area on the high res model the day before..

we are just not used to these synoptics & reloads in the most recent past-

as regards your timings comments- Maybe 3-4pm.......

S

-26.1c - Edgmond, near Newport, Shropshire on 10 January 1982. I remember it well, it fired my interest as I lived just a couple of miles away as a kid...

[bluearmy]

nice FAXES T96/T120 again. T120 looks to be inline with raw UKMO. looks to be around 12hours faster with saturdays precip than GFS

[Wonderland]

Latest fax out for Sunday has a front just clearing to our South after giving practically everywhere several hours of snow.

Heaven has come to earth!!

Atleast work will be quiet, I just won't be able to get home! Haha!

[Weather-history]

For the temperature to be -2C at 12pm (fair enough), but then to drop to -5C by 3pm, anyone with experience in climate physics will know that on an island which is predominantly affected by the Atlantic ocean, this just doesn't happen!

Shawbury

Maximum on the 12th December 1981: -12C

By 6pm it was -22C

It is possible but personally I don't think likely.

[phil nw.]

Yes the thing is with this run the bit of energy in the N.Jet that drives the Northerly is just strong enough to force the flow south enough so we end up on the cold side of the Jet.

http://www.meteociel...&mode=5&carte=1

This keeps us better placed later on when low pressure tries to attack again.

http://www.wetterzen...s/Rtavn1681.png

I can`t recall the last time i saw a possible battleground like this,without a high somewhere to our North.

Amazing stuff.

Edited December 15, 2009 by phil n.warks.

[johnholmes]

fro the Met O web site and its comments on Midlands area weather-lots of details for there and all the other main regions-this caught my eye

Cold air drainage into the river valleys results in large-scale frost hollows, with the Severn, Wye and Avon valleys enhancing the general frostiness of the western half of the Midlands. With snow cover, some remarkably low temperatures have been recorded, such as -25.2 °C at Shawbury, Shropshire on 13 December 1981 and -26.1 °C at Newport, Shropshire on 10 January 1982. This value at Newport is the lowest ever recorded in England.

I do remember the night I was on night duty at Manchester Airport and spoke on the direct line to Jodrell Bank who were reporting a similar value. As a result I rang the duty observer at Shawbury to see what his lowest had been, there were hourly Fax charts and teleprinter synoptic reports but the min occurred between two reports.

I won't tell you how the observer described going out in it felt!

to get back on topic-re GFS it is best to remember that even though, if you look at NW Extra, its detail is pretty comprehensive-its 'trends' rather than numbers one is looking at. IF snow cover occurs then values below-10C in cold drainage areas are going to occur-just how low then depends on subsequent day max's, no change in the lower 2-5000ft air, little flow at those heights and clear skies all night.

Edited December 15, 2009 by johnholmes

[TEITS]

Lets also not forget but the depth of lying snow can make a difference. You would see colder min temps with 1ft of lying snow compared to a dusting of 1-2cm.

Getting back on topic and my last post of this evening as im feeling jaded with all this model watching.

I know I sound like a broken record player but imagine its 1947, 1963. What do you think the models would be suggesting in F.I?

My answer is a return to our default weather pattern ASAP. I very much doubt the models would of continued suggesting bitter E/Nlys to +384. So this is why im delighted that the models are reluctant to bring a return to milder weather. Obviously I have no proof im what im saying and who knows maybe it will turn milder before xmas. However whilst there is uncertainity the chances of this cold spell continuing remain.

[Thundery wintry showers]

I think the projected temperatures on the GFS 18Z are completely plausible given the synoptics- the synoptics are one of the coldest possible options from here, but I think they would give rise to the sort of temperatures that the GFS is showing. On the other hand if Stephen had been criticising the temps that the GFS 12Z showed I would've agreed with him.

[Geordiesnow]

I'll see it when I believe it.. until then I remain massively sceptical!

I've never, myself, seen temperatures that low on the models (I didnt see the 12z though)

They often forcast them that low for the highlands and anytime where we get good charts but never come to the reliable timeframe it would seem.

GFS temp charts are however not the best but -15 is certainly not impossible in rural areas with snow cover, light winds and clear skies.

I'm pretty sure the charts tomorrow morning won't be as good as tonight's 18Z but if it still shows some snow potential regarding the Northerly then thats good enough for me.

[Richard Lake]

Its not the figures I'm discounting as such, it's the areas there forecast to, and the way the temperature are changing.

For the temperature to be -2C at 12pm (fair enough), but then to drop to -5C by 3pm, anyone with experience in climate physics will know that on an island which is predominantly affected by the Atlantic ocean, this just doesn't happen!

If you think it's going to happen, good luck to you!

It was only about 3 years ago that Grimsby right on the East Coast never rose from its night-time of -5C. I am sure these kind of temperatures happen more often then we think/we record.

[paul tall]

fro the Met O web site and its comments on Midlands area weather-lots of details for there and all the other main regions-this caught my eye

Cold air drainage into the river valleys results in large-scale frost hollows, with the Severn, Wye and Avon valleys enhancing the general frostiness of the western half of the Midlands. With snow cover, some remarkably low temperatures have been recorded, such as -25.2 °C at Shawbury, Shropshire on 13 December 1981 and -26.1 °C at Newport, Shropshire on 10 January 1982. This value at Newport is the lowest ever recorded in England.

I do remember the night I was on night duty at Manchester Airport and spoke on the direct line to Jodrell Bank who were reporting a similar value. As a result I rang the duty observer at Shawbury to see what his lowest had been, there were hourly Fax charts and teleprinter synoptic reports but the min occurred between two reports.

I won't tell you how the observer described going out in it felt!

I would absolutely LOVE to go out in a temperature like that. I remember that cold snap as a young boy but I doubt the temperature in North East England was anything like that, maybe a -12 to -15?

[cyclonic happiness]

Well inland and sheltered by mountains to the west such as in W Midlands, English/Welsh Borders and in a stagnant or slack cold airmass - quite possible. The influence from the Atlantic would be fairly minimal with little wind flow.

Unusual synoptics evolving over coming days, which will really put the NWP to the test, and expect some rather low temps inland where winds fall light and there's snow cover.

I have vague memory from 1981 of my mother tucking the curtains in and making a big fuss about all the drafts being blocked up as she kept saying "the cold is trying to get in", she's never said anything like that since?

That cold spell we got down to -25'c in Nuneaton what with being in a big valley with all the valley's leading into it from miles around.

We used to say you could expect it to get down to at least -10'c every winter at one point, but that notion has dissapeared with the warmer winters we had recently.

(I think that Nuneaton should have it's own weather station, as I'm sure it would end up as being one of the coldest areas in England away from the mountains)

Edited December 15, 2009 by cyclonic happiness

[chapmanslade]

I posted a link a year or two back on the winter extremes of 1981/2 but sadly the link is dead now

There is an analysis on another forum here http://www.ukweatherworld.co.uk/forum/forums/thread-view.asp?tid=6681&start=1

Great newspaper extracts later in the thread

Edited December 15, 2009 by chapmanslade

[Hairy Celt]

fro the Met O web site and its comments on Midlands area weather-lots of details for there and all the other main regions-this caught my eye

Cold air drainage into the river valleys results in large-scale frost hollows, with the Severn, Wye and Avon valleys enhancing the general frostiness of the western half of the Midlands. With snow cover, some remarkably low temperatures have been recorded, such as -25.2 °C at Shawbury, Shropshire on 13 December 1981 and -26.1 °C at Newport, Shropshire on 10 January 1982. This value at Newport is the lowest ever recorded in England.

I do remember the night I was on night duty at Manchester Airport and spoke on the direct line to Jodrell Bank who were reporting a similar value. As a result I rang the duty observer at Shawbury to see what his lowest had been, there were hourly Fax charts and teleprinter synoptic reports but the min occurred between two reports.

I won't tell you how the observer described going out in it felt!

to get back on topic-re GFS it is best to remember that even though, if you look at NW Extra, its detail is pretty comprehensive-its 'trends' rather than numbers one is looking at. IF snow cover occurs then values below-10C in cold drainage areas are going to occur-just how low then depends on subsequent day max's, no change in the lower 2-5000ft air, little flow at those heights and clear skies all night.

I'll tell you then, people: don't touch anything metal, don't try to drink anything, get back indoors promptly!

[Paul]

QUick reminder folks - this is the model thread, general winter discussion has it's own thread...

As you may expect the GFS operational is very much at the cold end of the spectrum on the ensembles - weird that the ensemble control is very similar to it as well.