Winter / Autumn 2009-10 Part 4

[Weather-history]

And if you make it the sub 3.0 we often mention, the current gap without is 12 years. This is completely unprecedented in the instrumental record period.

Thats true for a calendar month but here's the catch, we had a 11 week period that was sub 3.0C

29th November 2008-13th February 2009 CET: 2.8C

Now the question is which would you think logically is more difficult to get, a calendar month that is sub 3.0C or any 11 week period?

A specific 28 day/30 day or 31 day period or any 77 day period (which is in effect 2 and a half calendar months long)?

Edited November 14, 2009 by Mr_Data

[reef]

In February 2007 (9th), there was a very significant snow event that gave about 4-5 inches that fell during daylight hours right down to sea level. These couple of days were the only notable snow events, with the rest of a winter being a write off.

http://www.wetterzentrale.de/topkarten/fsreaeur.html

http://www.wetterzentrale.de/topkarten/fsreaeur.html

http://www.wetterzentrale.de/topkarten/fsreaeur.html

The event was caused by a (channel) low pressure coming up from the south and meeting cold air over us from previous days.

As for SSTs there don't tend to make that much of a difference, with we are quite a bit inland from the NNW winds that tend to being the snow showers here in winter. However apart from one day in Febraury last year, these have failed to deliver for teh past 3 winters.

SSTs made a big impact around here. The 9th February event was one of the biggest disappointments of that winter. Despite the cold air being there and the precipitation arriving, due to the low to the south a flow was dragged in from the North Sea and the high SSTs did their damage. All we got in the end was a bit of graupel in the morning followed by a day of rain and sleet, which became heavier in the evening. Meanwhile 20 miles inland there was a good dumping of snow.

[osmposm]

Thats true for a calendar month but here's the catch, we had a 11 week period that was sub 3.0C

29th November 2008-13th February 2009 CET: 2.8C

Now the question is which would you think logically is more difficult to get, a calendar month that is sub 3.0C or any 11 week period?

A specific 28 day/30 day or 31 day period or any 77 day period (which is in effect 2 and a half calendar months long)?

I don't know the answer to that, Mr D, but logic/common sense can often a poor measure in my experience. But I take your point. I suppose it would be posssible to work out the respective probabilities in a hypothetically non-changing climate, but it's way beyond my mathematical abilities.

Ultimately, though, of course, we'd have to analyse all the other possible, say, 70 day periods in the entire daily CET record since 1772, and see how often it occurs....but that's an even tougher job, I'd have thought, since I think there must be over 86,000 of them!?!

Edited November 14, 2009 by osmposm

[BLAST FROM THE PAST]

LRF for winter to be posted on Tuesday 17th, please pose questions to RJS with thanks

BFT;P

[LomondSnowstorm]

LRF for winter to be posted on Tuesday 17th, please pose questions to RJS with thanks

BFT;P

Looking forward to reading it. Enjoy your break from the forum and hope to see you back posting in the New Year.

CW

[Summer of 95]

I think SSTs can have a big impact in coastal areas if both the autumn and winter are mostly very warm. July 2006 was a record-breaking hot month, Autumn 2006 was a record-breaking warm one and the winter of 2006/07 was then one of the top ten warmest winters on record. The result was that the SSTs around Britain were exceptionally high. Thus, when we got synoptically potent-looking northerlies around 22-25 January, 5-9 February and 18-20 March accompanied by fairly deep cold air, the SST modification was so huge that many of the usually-favoured northern and eastern coasts struggled to see any accumulations of snow at all. At Cleadon, a NE'ly from the Arctic on 22nd January, with 850hPa temperatures of around -8C, gave a maximum of 7.5C, and even Newton Aycliffe in Durham managed 6.3C.

But then again, two of the most dramatic November northerlies of the last two decades for north and east-facing coasts- 17th November 1995 and 8th/9th November 2001- occurred when SSTs in the North Sea were unusually high following exceptionally warm Octobers. Despite this, there was a good peppering of sleet and snow showers, and the sharp contrast between the deep cold air and the anomalously warm sea also produced a fair amount of thundery activity.

But no matter how anomalously high those SSTs are, a prolonged spell of below average temperatures in winter will tend to bring them down close to normal quite quickly, as happened in the Decembers of 1995 and 2001.

I think soil temps have a part to play too; the thing about 2004/5 was that there were daffodils out here in mid-January; far earlier than any other winter (even 89/90 didn't see them till mid-Feb). I believe that easterly in late Feb/early Mar failed to deliver away from the SE not because of SSts, but because after reaching eastern Britain they were then modified further by 150 miles of anomalously warm ground; hence the snow either not settling or melting within a few hours. In 04/5, although it wasn't as mild as some winters, the short duration and rarity of air frost was striking; the first one wasn't till 14th Nov (Still waiting this year) and never did we get more than a couple of successive below-freezing nights (every other winter has always managed 4-5 at least). Additionally the lowest maximum was around 2.5C, and only a handful of days in Dec and Jan failed to hit 5C. In terms of duration of, not number of days with, air frost it was probably the most frost-free winter I can remember. Lucky was that snow at Christmas; it settled because it fell when the ground was coldest. In mid-Jan or later it would have melted as it landed I reckon.

2006-7 did have that week of frost around Christmas, and a few days of frost before that February snow; also 1994/5 had a week of frosty, foggy weather in the run-up to Christmas.

[Thundery wintry showers]

The soil temperatures may have been a factor during February 2005 but I don't think they were the biggest factor. Maximum temperatures across most of the country reached 4 or 5C on most days, and minimum temperatures struggled to get significantly below freezing- that combination is, at best, only likely to support a freeze-thaw type of cold spell.

The importance of temperature was illustrated by the fact that Cleadon near the Tyne & Wear coast had maxima near 4-5C and minima near 1C for most of the spell, and there was a lot of wet snow that struggled to settle (with the exception of the northerly that preceded it, which brought 3cm early on the 20th). In contrast, further inland and slightly further up, Newton Aycliffe had maxima of 2 or 3C for most of the spell, and snow accumulated to an aggregate depth of 16cm.

But the Durham area also had a very mild winter- January 2005 was the warmest January since 1989. This suggests to me that air temperatures (including raw air temperature and dewpoints) were probably a larger factor than soil temperatures.

[Typhoon John]

The soil temperatures may have been a factor during February 2005 but I don't think they were the biggest factor. Maximum temperatures across most of the country reached 4 or 5C on most days, and minimum temperatures struggled to get significantly below freezing- that combination is, at best, only likely to support a freeze-thaw type of cold spell.

The importance of temperature was illustrated by the fact that Cleadon near the Tyne & Wear coast had maxima near 4-5C and minima near 1C for most of the spell, and there was a lot of wet snow that struggled to settle (with the exception of the northerly that preceded it, which brought 3cm early on the 20th). In contrast, further inland and slightly further up, Newton Aycliffe had maxima of 2 or 3C for most of the spell, and snow accumulated to an aggregate depth of 16cm.

But the Durham area also had a very mild winter- January 2005 was the warmest January since 1989. This suggests to me that air temperatures (including raw air temperature and dewpoints) were probably a larger factor than soil temperatures.

I enjoyed the 04/05 Winter, I ended up with closer to 15cm of snow at the peak of the period. I remember at that point (I think it was that point, I can never remember the dates) being gutted that the front that came from the East brought sleet and rain instead of snow. We had a drive up to Weardale through Tow Law, Consett, and up to Edmundbyers/Blanchland area where I lost our shovel and was in snow over my waist!

Edited November 15, 2009 by fozi999

[Alex95]

2007/08 wasn`t a total loss if you liked freezing fog and a few ice days in december,and a brief easterly in January,and a little cold zonailty in the same month.

2006/07 did give a very large snowfall on february 9th and almost got down to -6c on the 7th.

Yes but despite the Jan 2008 easterly delivering 10cm in Newcastle City Centre, and 15cm nearby, I received a measly 2cm as the heaviest band of snow showers had a gap in it, so despite hearing thunder and seeing curtains of snow, I got a dusting. 2006/07 had no significant snow whatsoever in Newcastle so that year was a write off for snow here.

The soil temperatures may have been a factor during February 2005 but I don't think they were the biggest factor. Maximum temperatures across most of the country reached 4 or 5C on most days, and minimum temperatures struggled to get significantly below freezing- that combination is, at best, only likely to support a freeze-thaw type of cold spell.

The importance of temperature was illustrated by the fact that Cleadon near the Tyne & Wear coast had maxima near 4-5C and minima near 1C for most of the spell, and there was a lot of wet snow that struggled to settle (with the exception of the northerly that preceded it, which brought 3cm early on the 20th). In contrast, further inland and slightly further up, Newton Aycliffe had maxima of 2 or 3C for most of the spell, and snow accumulated to an aggregate depth of 16cm.

But the Durham area also had a very mild winter- January 2005 was the warmest January since 1989. This suggests to me that air temperatures (including raw air temperature and dewpoints) were probably a larger factor than soil temperatures.

I remember that spell, and it wasn't as disappointing here as it was for some as I did measure 15cm on one afternoon, but most other days saw about 10cm in the morning, but by the afternoon it melted quite a bit in between the showers with water dripping off trees etc so what could have been an amazing spell was ruined, and imo it was mostly due to the lack of cold pooling in Europe. If Europe had been colder, the warm soil temperatures would probably have been overcome.

Edited November 15, 2009 by alza

[fromey]

Morning everybody, i probaly going to get shot down for saying this but i remember watching Joe B over in the states on some tv programe/news and his forecast as you are all aware goes for a very cold winter, but what sticks out in my mind he did say though that we would be very mild in november and begining of december, isnt this what were seeing now??

i cant find the link to post the video but if anybody has it feel free to post it.

please be gentle with your replys as i know very little about charts, PDOs, -nao etc etc, im still learning.

your thoughts would aid me in learning.

many thanks

Fromey

[Solar Cycles]

Morning everybody, i probaly going to get shot down for saying this but i remember watching Joe B over in the states on some tv programe/news and his forecast as you are all aware goes for a very cold winter, but what sticks out in my mind he did say though that we would be very mild in november and begining of december, isnt this what were seeing now??

i cant find the link to post the video but if anybody has it feel free to post it.

please be gentle with your replys as i know very little about charts, PDOs, -nao etc etc, im still learning.

your thoughts would aid me in learning.

many thanks

Fromey

Indeed he did fromey, so up to now his forecast is shaping up well.

[Terminal Moraine]

I think soil temps have a part to play too; the thing about 2004/5 was that there were daffodils out here in mid-January; far earlier than any other winter (even 89/90 didn't see them till mid-Feb). I believe that easterly in late Feb/early Mar failed to deliver away from the SE not because of SSts, but because after reaching eastern Britain they were then modified further by 150 miles of anomalously warm ground; hence the snow either not settling or melting within a few hours. In 04/5, although it wasn't as mild as some winters, the short duration and rarity of air frost was striking; the first one wasn't till 14th Nov (Still waiting this year) and never did we get more than a couple of successive below-freezing nights (every other winter has always managed 4-5 at least). Additionally the lowest maximum was around 2.5C, and only a handful of days in Dec and Jan failed to hit 5C. In terms of duration of, not number of days with, air frost it was probably the most frost-free winter I can remember. Lucky was that snow at Christmas; it settled because it fell when the ground was coldest. In mid-Jan or later it would have melted as it landed I reckon.

2006-7 did have that week of frost around Christmas, and a few days of frost before that February snow; also 1994/5 had a week of frosty, foggy weather in the run-up to Christmas.

[Terminal Moraine]

Hmm, dont' know what happened to that post, I'll try again.

Having recorded soil temperatures at various depths for around 30 years I've found that they tend to be reactive to air temperature in winter rather than having a proactive influence upon it.

Obviously snow will lie more readily on frozen ground than on unfrozen ground but if the air temperature is low enough even a thin cover will persist for several days over an unfrozen soil surface and a deep cover can persist for weeks.

Even soil with a temperature of 7c at 5cm depth will freeze rapidly at the surface and if the cold weather persists the temperature at that depth can fall as much as 6c within 48 hours. If a snow cover is present the slow melt from the undersurface of the snow gradually chills the soil until an equilibrium is reached at a point between 0c and 1c, slowly reducing the rate of thaw from beneath as it does so.

The greatest effect of high soil temperature on snow cover occurs when the air temperature is only just low enough for snow to begin to settle, in such cases snow may fall for many hours with only a slight accumulation which then thaws quickly from beneath once the snow stops, even if the air temperature falls a little below 0c.

If the air mass is cold enough, and the snow heavy enough, a high soil temperature will have little effect on the rate of accumulation.

[Snowyowl9]

In 04/5, although it wasn't as mild as some winters, the short duration and rarity of air frost was striking; the first one wasn't till 14th Nov (Still waiting this year) and never did we get more than a couple of successive below-freezing nights (every other winter has always managed 4-5 at least).

First air frost in 2005 was november 17th,just missed out on the 14th at 0.2c

Have to go back to 2000 december 16th very late for the first air frost,aswell as some light snow at the same time.

http://www.wetterzentrale.de/archive/ra/2000/Rrea00120001216.gif

http://www.wetterzentrale.de/archive/ra/2000/Rrea00220001216.gif

[Glaswegianblizzard]

Something I am noticing - not my own personal observations but one that I find on a site I visit. When you compare the last few days with the corresponding dates last November, this year is coming out slightly colder in Glasgow (or Bishopton, where the weather station is).

Just find this interesting regarding a very mild winter some people seem to be predicting. On this basis, although we are getting few sub zero lows at night, the day time temperatures are not really suggesting anything like it as far as I can see. Would it not take a major shift in weather patterns now to give us either a very mild or very cold winter? Certainly I don't see anything to give up hope of a cold winter, although I would prefer some more crisp, dry mornings than we've had.

Suggests to me that one is no more or less likely than the other, and in my own humble opinion, if anything were more likely, it would be average or moderately cold. Interesting to see if we continue to see the gradual lowering of temperatures into December. I would guess at 5-7 degrees being seen a lot if it continues this way here - no more than a hunch.

[Thundery wintry showers]

November has had near-average temperatures so far whereas last November had above-average temperatures until the 21st when a succession of northerly outbreaks started up. So it isn't much of a surprise.

But the second half of November looks like being exceptionally warm with frequent southerly and south-westerly winds.

[shuggee]

Yes the first lying snow of the season last year was overnight Nov 22/23 in the city centre here. Not seen a flake or a hill top with any on yet - and there's no sign of anything before month end...

[Geordiesnow]

Yes the first lying snow of the season last year was overnight Nov 22/23 in the city centre here. Not seen a flake or a hill top with any on yet - and there's no sign of anything before month end...

Do you know how the Scottish Highlands is doing with snowfall? I would of thought it be quite below average with all the mild and dry conditions we had. Got to say, i have not saw the snow graphic much on the BBC charts much so far and i probably won't see it all that much this week either.

[shuggee]

There's some posts here GS:

http://forum.netweat...s/page__st__136

I haven't been north of Perth or Arbroath this month.

[Methuselah]

There was a dusting above about 3000ft earlier on today...I think it's mostly gone now, though?

[LomondSnowstorm]

There's some posts here GS:

http://forum.netweat...s/page__st__136

I haven't been north of Perth or Arbroath this month.

West Lomond hasn't had any snow on it this November, which is quite unusual as it has usually had some by now. Obviously an early start to winter is by no means an indicator of the rest of winter being cold, nor is a late start neccesarily a bad thing either (I think 1978/79 had a fairly mild November?). But it does make you feel a bit better to see the first snow of the winter falling fairly early, if only to remind you what it looks and feels like after months without it!

[Don]

November has had near-average temperatures so far whereas last November had above-average temperatures until the 21st when a succession of northerly outbreaks started up. So it isn't much of a surprise.

But the second half of November looks like being exceptionally warm with frequent southerly and south-westerly winds.

Are you doing a mid month forecast update this month?

[Thundery wintry showers]

I will be putting it up tomorrow- it definitely needs one as the proposed cold third week with continental air isn't going to happen.

[sundog]

West Lomond hasn't had any snow on it this November, which is quite unusual as it has usually had some by now. Obviously an early start to winter is by no means an indicator of the rest of winter being cold, nor is a late start neccesarily a bad thing either (I think 1978/79 had a fairly mild November?). But it does make you feel a bit better to see the first snow of the winter falling fairly early, if only to remind you what it looks and feels like after months without it!

Id be happy just to get few decent frosts at this point in the season. Ive only had 2 slight frosts so far. I think that is even worse then at the same point during the Autumn/winter season of 06/07. That season i had to wait till Dec 23rd for my first air frost,i hope i dont have to wait as long this yr.

[J10]

SSTs made a big impact around here. The 9th February event was one of the biggest disappointments of that winter. Despite the cold air being there and the precipitation arriving, due to the low to the south a flow was dragged in from the North Sea and the high SSTs did their damage. All we got in the end was a bit of graupel in the morning followed by a day of rain and sleet, which became heavier in the evening. Meanwhile 20 miles inland there was a good dumping of snow.

Often we miss out here being so close to the coast, when inland, especially on high ground, they get the snow, so I know the feeling.