December 16 2009 a month long snowy cold spell begins

[damianslaw]

Not sure if I have my dates quite correct I think it was Thursday 16 or 17 December 2009 when an easterly arrived ushering in very cold uppers and snow into many eastern parts. This heralded the start of for many a month of very cold and at times snowy weather. Possibly the coldest monthly period since Feb 91, it was colder I think.. anyone have the stats.

Here we had heavy snow on the Sunday 19th and Monday 20th. The period leading up to Christmas was very cold with a couple of ice days. Boxing Day brought milder uppers but these lasted a day or two and the cold came back. Further snow on 5 Jan followed by a run of ice days. The cold relented after the 15th.

[LetItSnow!]

I think I read on here that mid-December 2009 to mid-January 2010 managed a sub-zero CET. It’s a pity in a way the synoptics didn’t lined up with a calendar month or we would have seen our coldest month probably since the 1980s. Of course December 2010 would go to prove that we could get it sub-zero for a whole month. Imagine if January AND December had both been below freezing. 

Reminds me of a thread on here IIRC, about notable warm/cool/hot/cold spells that are hidden by the C.E.T. due to half-monthly periods. A couple of months in 2005 were like that, second half of August 1938 etc. etc. 

[Optimus Prime]

The period 17th December 2009 - 15th January 2010 averaged -0.2 celsius. 

[LetItSnow!]

4 hours ago, Optimus Prime said:

The period 17th December 2009 - 15th January 2010 averaged -0.2 celsius. 

The coldest January since 1979 that never was...

[damianslaw]

8 hours ago, Optimus Prime said:

The period 17th December 2009 - 15th January 2010 averaged -0.2 celsius. 

Coldest 4 week period possibly since Feb 1-28 1986. Beaten only since by late Nov to late Dec 10.

[Summer8906]

I seem to remember the cold had started a little earlier, by the weekend of the 12th/13th, but wasn't especially intense, with temps just a little below average. It was an interesting evolution IIRC, first of all the Atlantic lows which had dominated November were blocked by a Scandinavian high, then a north or northwesterly type followed, then pressure fell in situ with a slack cold slow moving low.

The first memory of real, intense cold I had was on the Saturday (19th) which was sunny, a polar low of some kind was forecast to cross from NW-SE and there was the possibility of snow from this, but in the event it produced either rain or nothing at all here.

The following days were then mostly cold and dry if I remember right, but there was a marginal rain-snow event on the 21st, and in south Hampshire there was a notable freezing rain event on the 23rd, which I recall as I was carrying a computer and slipped up - it made the CD-ROM drive behave a bit oddly (though it was still functional) after that. This was during the slack cold low phase I think, and what happened is that convection formed over the Channel before moving inland but it produced freezing rain rather than snow. The airmass was inherently northerly, but was returning on a SW-NE track, so some similarities with the February 3 event earlier the same year. Further north it was dry.

In north Hampshire, round Basingstoke, however there was heavy lying snow on the 23rd. I think this was from the event on the 21st.

I was in northwest England over the Christmas period, and I do remember somewhat milder weather arrive around the 24th and persist until the 27th, with temps maybe a degree or so above average. Thereafter the colder air moved south again, though I do also remember a large low, located some way south, produce a lot of cold rain and wet snow towards the end of the year. Despite being centred, IIRC, in the Channel with all the country in the cold air, it mostly produced only cold rain, with snow on higher ground. This was very unlucky it seemed - widespread 3 or 4C temps with persistent rain were the norm for much of the country I think!

This also moved away so by New Years Eve it was dry and cold, making 2009 one of only a handful of years to both start and end settled (the following year, 2010, would be another one).

Into the new year a potent northerly developed and the first few days were cold, but very sunny. I think it was the 5th when the main event of the whole winter occurred, a polar low moving NNW-SSE produced heavy snow even in the south. Sadly the snow was quite light in south Hampshire though even a short distance north it was much heavier, with very deep snow in the NW Sussex-Hampshire-Surrey border area by Saturday 9th, enough to make progress difficult in places. Finally, after 23 years, proper January snow!

Temps were so cold that even close to the coast, where the snow was light, it persisted for a while, I remember temps crept very slightly above freezing on the 10th and there was slight thawing, however it wasn't until the 12th when a minor system moved along the channel that there was a thaw. This produced rain in southern Hampshire but more snow further north, if I remember right - a common pattern for a lot of these events in the 2009-13 period. That said it remained cold on the 13th and 14th, with lying snow doubtless persisting in north Hampshire.

Mild weather arrived on the 15th for a few days ending the main event, though during the rest of the month, colder spells returned regularly so even the second half of the month was I think marginally colder than normal, with cloudy anticyclonic weather and temps around 5C being common.

Then there was February. By contrast I didn't enjoy this month at all. While it was somewhat colder than normal, from about the 13th it was exceptionally dull with a lot of rain, with a lot of lows passing straight across southern England, with days of 5 or 6C and moderate to heavy rain being commonplace. That said there was about a week of cold dry weather with an easterly from about the 5th, which was originally forecast to persist but it seems the lows moved further north. As so often happens, the Midlands northwards had further, often heavy falls of snow. It was somewhat reminiscent of the second half of Feb 1994, but wetter and more cyclonic.

Finally on the 28th the sun came out, and despite the cold temps, the contrast in brightness from the previous two weeks made it feel spring was on the way. March though was not especially warm: the first week or so was sunny but with a very intense cold east wind, and the second half was rather wet and windy (the day before the spring equinox, i.e. the 20th, being exceptionally dull and gloomy for the time of year) There was also a notable day-darkness event on one of the last days of March, either the 29th or 30th, when it seemed to be going dark at 4pm. Normal for December but highly abnormal for the end of March when we had already switched to BST. So we had to wait until April for real spring that year - which thankfully, as is so often the case with April these days, was a gloriously sunny month with blue skies and low humidity.

Edited December 19, 2021 by Summer8906

[Harry233]

I remember this spell of weather very well. I think we got the first snow on the 17th December nothing too big just a few centimetres. Then we flew out to Tenerife for Christmas that year on the 20th and I remember it snowing very heavy on the 19th to the point Glasgow airport closed and we had our flights changed to Newcastle. We managed to get to out and I remember on the way home (27th) my dad saying that Perth had over a foot of snow. Couldn’t actually believe how much it had snowed I think there was about 40cm recorded by New Year’s Eve and about 60cm just north of Perth. I think we had snow cover right the way through till the end of January then it got milder for a week or so and the again we had more snow that February and it stayed until the end of March 2010. 

[JeffC]

I think it snowed on or about Sun 13th, I remember we had a rescue straight after it snowed, and then we had another serious one on the night of 21st, probably the heaviest snow I've ever driven in! Huge flakes.

I remember it because exactly 1 year later, it was even colder and there was a (relatively) significant earthquake...

Never a dull moment in my life lol

[damianslaw]

11 minutes ago, JeffC said:

I think it snowed on or about Sun 13th, I remember we had a rescue straight after it snowed, and then we had another serious one on the night of 21st, probably the heaviest snow I've ever driven in! Huge flakes.

I remember it because exactly 1 year later, it was even colder and there was a (relatively) significant earthquake...

Never a dull moment in my life lol

Probably Sunday 19th, the weekend before was dry and cold.

[JeffC]

3 minutes ago, damianslaw said:

Probably Sunday 19th, the weekend before was dry and cold.

Could be but I had it in my head there was a bigger gap time wise

[JeffC]

10 minutes ago, damianslaw said:

Probably Sunday 19th, the weekend before was dry and cold.

Just checked records, was Sun 20th  & Mon 21st...brain plays tricks...

[damianslaw]

Yes two back to back snowy days. Evening of 21st very memorable thunder snow. 

[cheeky_monkey]

This was the last hurrah of winters in the UK for me..i left to live in Canada for good on Jan 15, 2010...maybe this is why i dont remember it being as cold or snowy as the record shows..my memory has been tainted by the rest of the winter being in Canada and subsequent Canadian winters to follow where even a 1962-63 winter would be considered very mild here