Snow lying- date distribution

[Summer of 95]

Here's an interesting statistical quirk I've noticed:

No lying snow here in the middle third (11th-20th) of:

December and January both since before 1990 (presumably 1987 for Jan, the year before I moved here)

February since 1994

For the first third:

December: 1995

January: 2006

February: 2003

And the final third

December: 2005

January: 2004

February: 2005

Why has the middle part of each winter month been so consistently snowfree in recent times I wonder? There does seem to be a remarkable tendency for snowfalls to come at the beginning and end of winter months in the last 15 years; even cold months like Dec 1995, Feb 1996 and Jan 1997 had nothing in the middle. Another quirk is that every time I've seen lying snow in November, it's been between the 19th and 22nd. Yet March has seen lying snow in every third just since 2000.

[Thundery wintry showers]

I noticed the trend for November as well. It shows up on the CET data- during the 1961-90 and 1971-2000 periods, temperatures decline rapidly during the first half of November then show a sign of levelling off.

November temperatures for 1990-2005 showed a higher starting point, declining more sharply to values similar to the 30-year average values during 16-24 November, then from the 25th to 30th, there was a marked 'bulge' with temperatures a good 4C above those of the 30-year average periods.

The trend may be a regional as well as statistical quirk, as it's less easy to detect from my Cleadon records.

Snow lay in December during the 1993-2006 period in the following years:

First third: 1995, 1997, 1998

Middle third: 1998

Final third: 1993, 1995, 1996, 2000, 2001, 2003, 2005

For January:

First third: 1995, 1997, 2002, 2003

Middle third: 1993, 1994, 1999, 2001

Final third: 1995, 1996, 1998, 2003, 2004

For February:

First third: 1996, 1999, 2003

Middle third: 1994, 1996, 2000

Final third: 1993, 1994, 1996, 2001, 2002, 2004, 2005, 2006

Cleadon's statistics seem to show that in the cases of December and February, most snow events have occurred during the final third of the month. Nonetheless, there's still a detectable tendency for snowless middle thirds when the length and significance of snow events is taken into consideration- all of the "middle third" events listed were either just a dusting, or melted within a day of the accumulation.

[WBSH]

Yes, it is a trend I have noticed as well, also the same goes for cold spells with N'ly + E'lys always starting towards the end of the month for the last few years. Such examples include:

Feb 06: No lying snow for my location sadly, but very cold with lots of snow showers which lasted untill early March.

Dec 05: 2" from an Atlantic front hitting cold air on the 29th/30th.

Nov 05: No snow, but some biting N'lys at the end of this month after a warm autumn.

Feb 05: A remarkable spell of snow for SE especially that started in Late Feb and carried on towards mid-March and dumped 15cm of snow in Kent during it's peak.

Dec 04: Some snow around Xmas, although I don't remember where! My area was cold and very frosty with mins of -5c on boxing day morning.

Feb 04: Although my memory is little rusty, I remember western areas getting quite a bit of snow at the end of this month. None for me but cold.

Jan 04: Thundersnow on the 28th

Jan 03: 30th saw sudden blizzards that night.

My memory is not crystal clear so I may be slightly off with some of these "facts" and also most of it is just what I remember for my area.

Edited December 27, 2006 by WBSH

[Summer of 95]

I did wonder if cold events overlapping the calendar changes might be partly responsible for this- but no, only in 1995/6, 1996/7 and 2001/2 (in all cases Dec-Jan) has this happened regarding lying snow persisting from one month into the next. In fact if you take the date the snow actually first settled, the snow lying in mid-Feb 1991 can also be removed from the statistics as it fell on the 7-8th and stayed for over a week- leaving only Feb 1994 in the past 16 years having a snowy spell contained in the middle part of the month. And the final part of February has done particularly well considering it is shorter than all the others.

[paul tall]

Yes I've noticed the November trend.

As a kid in the 80's I remember a couple of snowfalls in November and noted they seemed to happen around the 21st. I may be wrong but I think we had a couple of november snowfalls in the 90's on or around the 21st.

[Thundery wintry showers]

I think you're right; the ones I remember are 21-22 November 1993, 17 November 1995, and 20 November 1996.

[Summer of 95]

I think you're right; the ones I remember are 21-22 November 1993, 17 November 1995, and 20 November 1996.

The 1993 and 1996 ones plus 20th November 1988 were the ones I was referring to; several places also had lying snow at the same time in 1985, 2004 and 2005.