Winter 2010/2011 Part 3

[Kentish Kiwi]

Seems to be quite a common characteristic of severe wintry months- even when northerly rather than easterly winds prevail, the southeast often ends up somewhat cloudier relative to average than other regions. It probably has a lot to do with the southeast frequently lying in the path of frontal systems associated with southerly tracking lows, giving mainly frontal snowfalls and extensive cloud cover, while further north there is more reliance on convective snowfalls with sunshine in between.

Possibly, but the vast majority of precipitation I received before the post-Christmas thaw was convective. Its just that the convection was as a result of an extended Thames streamer that set-up and at least in my location it produced prolonged spells of convective precipitation (genuinely 72 hours non-stop) and copious amounts of cloud cover, with very little in the way of 'sunshine and showers' as you might expect from such a set-up (from what I can vaguely remember at least).

On reflection though I'd be inclined to agree with your summary of 'mainly frontal' precip/cloud in the south as a general explanation, I certainly can't think of any other reason behind what seems to be quite a significant correlation, at least on the surface.

[Thundery wintry showers]

Interestingly what you describe was also a common characteristic of that easterly outbreak at the end of November and into the beginning of December. We had convective snowfalls over Lincolnshire and the SE associated with slow moving troughs aligned W-E which resulted in that infamous dry corridor from Lowestoft-Norwich-Peterborough-Abingdon and some pretty persistent snow just to the north and south. Meanwhile in eastern Scotland and north-east England any troughs tended to be aligned N-S, giving spells of heavy prolonged snow preceded and followed by sunshine and snow showers, and in between troughs there was usually a random scattering of clear spells and snow showers.

I imagine that the longer track over the North Sea further north, and the closer proximity to low pressure towards the SE, and the Wash/Thames streamer tendencies must be factors here- it's certainly an interesting point, it does seem harder to get a straightforward "sunshine and snow showers" setup in the SE than in the NE even when the snowfalls in the SE are relying on convection provided by the North Sea.

[AderynCoch]

That must be the perfect Greenland High on that chart - monstrous heights over Greenland itself causing a steep pressure gradient with the adjacent low and directing deep polar air southwards in the process, with the southeastern end of the high ridging towards us and thus channelling the whole shebang in our direction.

[Matty M]

Is there any meteorological reason for the following with regard to convective easterlies.

Showeres tend to last much longer just 10-20 miles inland than right on the coast?

For example during the last spell, inland Dublin around 10-20 miles inland had the highest precips deposits.

Showeres moved over the coasts and tended to peak in intensity just inland and grow in size?

Also even with well sufficient cold air with no marine boundary influence, the majority of coastal showers consisted

of 50% hail and 50% snow, while inland, they fell as all snow, even though temperatures were subzero at the coast?

That must be the perfect Greenland High on that chart - monstrous heights over Greenland itself causing a steep pressure gradient with the adjacent low and directing deep polar air southwards in the process, with the southeastern end of the high ridging towards us and thus channelling the whole shebang in our direction.

indeed we probably won't see another synoptic as good as that for 50 years, it was in the end the coldest month since 63'.

[Weather-history]

Central pressure of 1075 mb... That's not that far off the highest ever recorded (equivalent) sea level of 1085.6 mb which was recorded in Mongolia during December 2001.

Incredible to see such extreme high pressure almost exactly where we would want to see it (for cold in the UK).

Word of caution.

I suspect the pressure wasn't as high as that. There are issues with pressure modelling over Greenland. It exaggerates it. A lot of the archives showing such very high pressures over Greenland probably wasn't as high as that.

[Don]

Well, during the last week the outlook for the rest of Winter has been getting grimmer by the day! I'm going to have to say that this Winter is heading towards going a classic pearshape! I know 81/82 went a similar route but at least the first half of Jan brought some severe weather, wheras this month has brought nothing to the southern half of the UK in terms of cold and snow. I know that Scotland has done OK though. With more and more LRF's going for a mild February, I fear that it could be a painfully slow couple of months to come for cold weather lovers and may be a good time to take a holiday break somewhere! I agree with others that although you cannot deny that December was a classic and will be remembered for many years, if January and February do end up being mild and snowless, it won't matter, Winter 2010/11 will go down as being rather poor overall. I just hope that the outlook soon changes for the better, but looks unlikely with poor teleconnections. I'm also wondering if this is a sign that our colder than average weather is coming to an end with the next few Winters reverting back to pre 2008 types. You just never know with weather and always expect the unexpected. The last few years have proved that!

[AderynCoch]

I agree with others that although you cannot deny that December was a classic and will be remembered for many years, if January and February do end up being mild and snowless, it won't matter, Winter 2010/11 will go down as being rather poor overall.

Although it would be very disappointing if the rest of the winter were to be mild, I can't see winter as a whole being judged as poor: December will skew things considerably.

[North-Easterly Blast]

Well, during the last week the outlook for the rest of Winter has been getting grimmer by the day! I'm going to have to say that this Winter is heading towards going a classic pearshape! I know 81/82 went a similar route but at least the first half of Jan brought some severe weather, wheras this month has brought nothing to the southern half of the UK in terms of cold and snow. I know that Scotland has done OK though. With more and more LRF's going for a mild February, I fear that it could be a painfully slow couple of months to come for cold weather lovers and may be a good time to take a holiday break somewhere! I agree with others that although you cannot deny that December was a classic and will be remembered for many years, if January and February do end up being mild and snowless, it won't matter, Winter 2010/11 will go down as being rather poor overall. I just hope that the outlook soon changes for the better, but looks unlikely with poor teleconnections. I'm also wondering if this is a sign that our colder than average weather is coming to an end with the next few Winters reverting back to pre 2008 types. You just never know with weather and always expect the unexpected. The last few years have proved that!

Well the key was, that despite the severe cold for three weeks in Dec 1981 and in the first half of Jan 1982, the winter of 1981-82 wasn't severe; overall it was still only a cold rather than a very cold winter, and wasn't all it was cracked up to be given the exceptional cold earlier on.

It certainly looks as though this winter could be quite a let down, we had a totally unprecedented cold period pre Christmas then it was all over by December 27th / 28th, so unless something colder shows up soon, then winter 2010-11 will have effectively ended in late December. January and February just hardly seem to be able to deliver cold and snow nowadays, with last year only seeing a decently cold Jan / Feb for the first time since 1991 or even the mid 1980s. It just looks like a repeat of 1944-45 or 1996-97 where the second half of those winters was a big let down following the promising early winter cold, and even then those winters saw cold lasting into January unlike this year.

OK, there is still later this month and the whole of February left; there could be some life left in this winter and we could see a cold spell or two but prospects of this happening just seem to be diminishing every day that goes by.

Can we ever see a decently mild December and a cold January / February EVER AGAIN?

From when the extreme cold set in so early this winter I always had the fear that it had set in too early to last long enough to make this winter special, and that we could be in for a painfully frustrating January and February. The point was that in 1962-63 the extreme cold didn't set in until Dec 22nd / 23rd, not in late November, although there had been some cold spells in 1962 prior to Dec 22nd, but certainly nothing like the early cold spell we saw this year.

Edited January 13, 2011 by North-Easterly Blast

[Thundery wintry showers]

Can we ever see a decently mild December and a cold January / February EVER AGAIN?

From when the extreme cold set in so early this winter I always had the fear that it had set in too early to last long enough to make this winter special, and that we could be in for a painfully frustrating January and February. The point was that in 1962-63 the extreme cold didn't set in until Dec 22nd / 23rd, not in late November, although there had been some cold spells in 1962 prior to Dec 22nd, but certainly nothing like the early cold spell we saw this year.

I often see you asking these "can we get X ever again?" questions. As a general rule, barring questions that refer to cases of extreme cold scenarios that are invariably eroded by higher global temperatures, the answer to them tends to be yes, and I have little doubt that we will see that combination in the future. The current run of cold Decembers is almost certainly a statistical blip caused by anomalously cold synoptics as was the case with the run of cold Decembers in the 1960s.

Severe cold weather has a limited amount of "staying power" so it's always likely that an exceptionally cold spell in November/December will be followed by less cold weather in January and February, although it can vary between a 1981/82 type scenario and a scenario of continued cold snowy weather but less severity. Many were concerned that the cold had set in too early last winter (mid December) but while it's true that it peaked between then and 9 January the rest of the winter continued generally colder than average.

However, it's not as if the cold November/December were "wasted"- averaged nationally December 2010 was comparable to February 1963. If this winter is generally remembered as a letdown it perhaps illustrates that people's conceptions of a period of weather tend to be biased towards what happens late in the period- even if January and February are generally mild with no more snow it will still be colder and snowier than most winters were in the last 100 years.

[North-Easterly Blast]

I often see you asking these "can we get X ever again?" questions. As a general rule, barring questions that refer to cases of extreme cold scenarios that are invariably eroded by higher global temperatures, the answer to them tends to be yes, and I have little doubt that we will see that combination in the future. The current run of cold Decembers is almost certainly a statistical blip caused by anomalously cold synoptics as was the case with the run of cold Decembers in the 1960s.

Severe cold weather has a limited amount of "staying power" so it's always likely that an exceptionally cold spell in November/December will be followed by less cold weather in January and February, although it can vary between a 1981/82 type scenario and a scenario of continued cold snowy weather but less severity. Many were concerned that the cold had set in too early last winter (mid December) but while it's true that it peaked between then and 9 January the rest of the winter continued generally colder than average.

However, it's not as if the cold November/December were "wasted"- averaged nationally December 2010 was comparable to February 1963. If this winter is generally remembered as a letdown it perhaps illustrates that people's conceptions of a period of weather tend to be biased towards what happens late in the period- even if January and February are generally mild with no more snow it will still be colder and snowier than 2004/05 was (2004/05 being remembered for that modest easterly in the last third of February).

Yes very true - it is always likely that an early winter season cold spell will be followed by less cold weather in Jan and Feb - although to emphasise the point most often it is likely that it will be NO more than "less cold", and certainly not "much milder than average weather" in Jan and Feb. There was the exception with 1683-84, where the Dec was very cold and Jan and Feb were even colder still, but yes the majority of past very cold Decembers have been followed by less cold Jans and Febs although often still with a good deal of cold and snow around. The average CET of Januarys that have followed a very cold sub 1*C Dec is 2.0*C (certainly less cold than the Dec we have had but still colder than average overall). Only two Januarys out of 15 have been above 3.5*C after a very cold December (below 1*C).

Still, the predominance of mild or very mild Januarys and Februarys in the last 20 years along with in particular the lack of notably mild Decembers is clearly something startling. I know that Dec 2010 was certainly a freak event but the overall trend in the last 20 years appears to have been for a fairly often average, varied, and at times colder December followed by a mild January and February.

Still, the early season cold this winter broke on the 27th December, so if Jan and Feb are largely mild with little in the way of cold or snow, the vast majority (approaching 70%) of this winter will have been a let down, so in other words, two thirds or more of this winter would be poor. I think that if there is not much in the way of cold pre-Christmas my own mind is geared up for getting ready for Christmas and celebrating that, but once Christmas is over Jan and Feb just seem like a long couple of months to get through devoid of cold weather before spring and anything else starts. To think that winter ends even before the end of December just seems unthinkable. At least in 1981-82 the first half of January did bring some very cold weather. Feb that year was quite mild although it did become colder for a time after mid-month.

Edited January 13, 2011 by North-Easterly Blast

[AderynCoch]

even if January and February are generally mild with no more snow it will still be colder and snowier than most winters were in the last 100 years.

Indeed. Also, there was only fleeting snow here on Friday (amounting to no more than 1-2cm) but that was still more snow than I can remember in any January here other than 1996 and 2010! There may have been other January snowfalls which I don't remember over the last 20 years, but that's still a damning verdict on just how poor January has been for snow since 1987.

This month was never likely to match December: to do so would have made it the coldest January since 1963, the third coldest since 1881 and the joint fourth coldest since 1838. However, as someone showed elsewhere it would be statistically unusual for a January to be mild following such a cold December, and it will still be something of a letdown should this scenario entail.

[Thundery wintry showers]

Thinking about it, there is a sound basis behind this "bias towards the latter part of a season" phenomenon- if we get a mild December & January but a cold February then many snow lovers end up thinking "well the winter was saved by the February", while conversely a snowy December builds up hopes and expectations, whereupon a subsequent mild January and February end up as a huge anti-climax.

I also take the point that if two-thirds of the winter being a letdown, it will make it a letdown for the majority of the time. Trevor Harley expressed the view "what a pathetic end to a wonderful winter!" when covering February 1982's weather, which will probably end up echoing the feelings of many members of this forum if the weather continues in a similar vein through to the end of February.

In many ways it reinforces my feeling that I prefer cold and mild spells to be spread through the winter rather than concentrated all at one end- though it was amazing to get a sub-zero December.

[North-Easterly Blast]

Indeed. Also, there was only fleeting snow here on Friday (amounting to no more than 1-2cm) but that was still more snow than I can remember in any January here other than 1996 and 2010! There may have been other January snowfalls which I don't remember over the last 20 years, but that's still a damning verdict on just how poor January has been for snow since 1987.

This month was never likely to match December: to do so would have made it the coldest January since 1963, the third coldest since 1881 and the joint fourth coldest since 1838. However, as someone showed elsewhere it would be statistically unusual for a January to be mild following such a cold December, and it will still be something of a letdown should this scenario entail.

Of course it was highly unlikely that this month would be as cold as December, but the chances should equally have been good that there would still be a good deal of cold and snow around this month, although most likely less severe and prolonged than last month, rather than a sudden breakdown from extreme cold to mild in late December and early January. After such a cold December, even if there was a milder period in the first half of January, the very cold December should at least have increased the chances of further cold spells later in January and during February, rather than it reverting to a typical mild post 1988 Jan / Feb.

[Thundery wintry showers]

Indeed- it's pretty notable how the stats show an association between cold Decembers and, if anything, near or slightly colder than average conditions for January and February (so the winter relaxes its grip but doesn't disappear abruptly as it did in 1981/82). But we had that notable exception in 1982 and we could well be getting another one in 2011, although I retain suspicions that we could get some potent northerly blasts from time to time if the mid Atlantic ridge persists for the next few weeks.

[North-Easterly Blast]

Thinking about it, there is a sound basis behind this "bias towards the latter part of a season" phenomenon- if we get a mild December & January but a cold February then many snow lovers end up thinking "well the winter was saved by the February", while conversely a snowy December builds up hopes and expectations, whereupon a subsequent mild January and February end up as a huge anti-climax.

I also take the point that if two-thirds of the winter being a letdown, it will make it a letdown for the majority of the time. Trevor Harley expressed the view "what a pathetic end to a wonderful winter!" when covering February 1982's weather, which will probably end up echoing the feelings of many members of this forum if the weather continues in a similar vein through to the end of February.

In many ways it reinforces my feeling that I prefer cold and mild spells to be spread through the winter rather than concentrated all at one end- though it was amazing to get a sub-zero December.

I equally prefer cold spells to be spread through the winter then there is always something to watch for in the models and look forward to. 1985-86 was very much the reverse of 1981-82 - however, there was some cold weather around at the back end of December and in the early part of January, so 85-86 wasn't without its cold moments until later on.

81-82 felt like a winter of two halves, an early cold winter but mainly mild second half

85-86 was a similar winter of two halves the other way round, mainly mild first half then a late cold winter.

Although if Jan & Feb 2011 are largely mild with hardly any cold / snow then winter 2010-11 still won't even feel like a winter of two halves if it is finished by Dec 27th never to return, a large part of it will still have been rubbish and Jan and Feb will still feel like a long two months to be devoid of winter.

Edited January 13, 2011 by North-Easterly Blast

[AderynCoch]

Is there really anything to suggest that this month will end up being particularly mild? The CET is currently going above average, but the southwesterlies shouldn't last too long before cooler temperatures return - hardly a return to December, but temperatures perhaps no higher than average?

Writing off February would be very premature. I remember in November when there was no sign of any early cold on the horizon, but look what happened.

[North-Easterly Blast]

Indeed- it's pretty notable how the stats show an association between cold Decembers and, if anything, near or slightly colder than average conditions for January and February (so the winter relaxes its grip but doesn't disappear abruptly as it did in 1981/82). But we had that notable exception in 1982 and we could well be getting another one in 2011, although I retain suspicions that we could get some potent northerly blasts from time to time if the mid Atlantic ridge persists for the next few weeks.

In fact history says that after a cold December, average to mild in Jan & Feb is as rare as getting a sustained deep freeze through the rest of winter (like 1683-84), and the most frequently seen outcome after a very cold December is for often colder than average conditions in the rest of the winter although less cold than in December.

Is there really anything to suggest that this month will end up being particularly mild? The CET is currently going above average, but the southwesterlies shouldn't last too long before cooler temperatures return - hardly a return to December, but temperatures perhaps no higher than average?

Writing off February would be very premature. I remember in November when there was no sign of any early cold on the horizon, but look what happened.

More than likely not the very mild 6*C CET Januarys that have been a feature in recent years, but judging by the model output we may well struggle to avoid an above average month.

[Rollo]

Yes very true - it is always likely that an early winter season cold spell will be followed by less cold weather in Jan and Feb - although to emphasise the point most often it is likely that it will be NO more than "less cold", and certainly not "much milder than average weather" in Jan and Feb. There was the exception with 1683-84, where the Dec was very cold and Jan and Feb were even colder still, but yes the majority of past very cold Decembers have been followed by less cold Jans and Febs although often still with a good deal of cold and snow around. The average CET of Januarys that have followed a very cold sub 1*C Dec is 2.0*C (certainly less cold than the Dec we have had but still colder than average overall). Only two Januarys out of 15 have been above 3.5*C after a very cold December (below 1*C).

Still, the predominance of mild or very mild Januarys and Februarys in the last 20 years along with in particular the lack of notably mild Decembers is clearly something startling. I know that Dec 2010 was certainly a freak event but the overall trend in the last 20 years appears to have been for a fairly often average, varied, and at times colder December followed by a mild January and February.

Still, the early season cold this winter broke on the 27th December, so if Jan and Feb are largely mild with little in the way of cold or snow, the vast majority (approaching 70%) of this winter will have been a let down, so in other words, two thirds or more of this winter would be poor. I think that if there is not much in the way of cold pre-Christmas my own mind is geared up for getting ready for Christmas and celebrating that, but once Christmas is over Jan and Feb just seem like a long couple of months to get through devoid of cold weather before spring and anything else starts. To think that winter ends even before the end of December just seems unthinkable. At least in 1981-82 the first half of January did bring some very cold weather. Feb that year was quite mild although it did become colder for a time after mid-month.

I see this from a totally different standpoint, we have become used to over many years the odd cold spell on winter lasting but a few days and here we are moaning about a mild spell (the first real one of the winter) after a 4 week long severe and in some places snowy as well.

It would be nice to see another 10 day freeze up at least but we have had some goodies and I would be quite amazed if there was not some more cold to follow. Most winters appear to produce snow in February but not a lot prior to that so with at least 6 weeks of true winter left lets hang fire and give this winter a further chance to go down in the record books.

[Weather-history]

It looks as though another winter month goes by with a distinct lack of Atlantic gales. I think we have to go back to January 2009 for the last winter month where we had a windy and stormy spell during a winter month down here.

[Thundery wintry showers]

I agree, and it's also worth noting that we have to go back to January 2008 for our most recent prolonged mild zonal spell because in January 2009 temperatures were near rather than above average when the westerlies dominated.

[mushymanrob]

Indeed- it's pretty notable how the stats show an association between cold Decembers and, if anything, near or slightly colder than average conditions for January and February (so the winter relaxes its grip but doesn't disappear abruptly as it did in 1981/82). But we had that notable exception in 1982 and we could well be getting another one in 2011, although I retain suspicions that we could get some potent northerly blasts from time to time if the mid Atlantic ridge persists for the next few weeks.

after viewing this mornings runs im cautiously optimistic that we are going to get another 1982!

[Thundery wintry showers]

We may well do as far as the winter quarter is concerned- I struggle to see where even a flake of snow is going to come from this side of February now, although temperatures will often be a little below average. February might contain one or two wintry spells but all of the longer-term signals that I've seen are suggesting a milder than average month.

Where this year might potentially differ is in the spring- as Mr_Data posted recently there is a strong tendency for La Nina winters to be followed by significant wintry spells in the spring (the most recent example being 2007/08), but that doesn't mean that it's a given of course!

[Terminal Moraine]

We may well do as far as the winter quarter is concerned- I struggle to see where even a flake of snow is going to come from this side of February now

I was thinking the same myself, TWS, after viewing the charts this evening. Jan 2011 could well end up joining the ignominious group of 1992, 1998, 2006 and 2008 all of which had only one morning with lying snow here.

It won't be the least snowy Jan' on record, that honour goes to 1989 which had just one day with sleet, but it's certainly a marked contrast to December.

[Thundery wintry showers]

I am getting a hunch that this season is more likely to end up as a topsy turvy one in the manner of 1890/91, rather than the straightforward progression of 1981/82. 1890/91 had that record-breaking cold December, a milder January, and then a notably mild dry sunny February, which was synoptically similar to the recent spell of 8-20 February 2008. A sudden switch to very cold snowy weather then occurred in early March 1891 and there were further snowfalls in the following May.

I am struck by the way the teleconnections are pointing towards a February with a similar pattern to February 1891 (high pressure over the UK extending into Europe) and the strong La Nina, which in recent years has often been associated with notable snow events in the spring. Certainly something to bear in mind.

Some sample charts to back up my suspicions:

http://www.wetterzentrale.de/pics/archive/slp/1891/Rslp18910218.gif

http://www.wetterzentrale.de/pics/archive/slp/1891/Rslp18910224.gif

http://www.wetterzentrale.de/pics/archive/slp/1891/Rslp18910302.gif

http://www.wetterzentrale.de/pics/archive/slp/1891/Rslp18910308.gif

[abbaman]

If cfs run of the jet stream we are looking for the rest of winter being mild but that is raw data. But I think if we get a bad late nov Early dec er will get a mild Jan , Feb and March. I also have looked at metoffices cfs raw data as well and it's the same as the raw data for the jetstream on here. Also my weather stations raw data as the same as both the jetstream rawdata on here and the metoffice. But with a few cold spells but not under -2 and I have done a my own long range forecast and for rest of Jan Feb March we are sticking to a low mild winter. As I have been given a very rare copy of when there was a late Nov Early Dec snowfall. But can not send it as it is private doc. 1956 is one when it happend and 1962 dec to feb 1963. And this is an extract from that page. In 1963 the cold weather started in December 1962 and persisted through to February 1963. It was a terrible time for people especially in the Southwest of England where many were cut off and trapped in their homes for long periods of time. Whatever global warming brings there will still be from time to time cold winters but perhaps they will never be as spectacular or as devastating as those mentioned above.