Summary for February 2006

=========================

HEADLINE:DULL, COLD START: UNSETTLED/MILDER 12TH-19TH. WINTRY END

(last updated: 01/1100 MARCH)

Location: Tawfield/Wooden Hill area of SW Bracknell, Berkshire, UK

Altitude 80 m (other location details see elsewhere on web site.)

(temperatures [standard screen] degC; rainfall/melted snowfall mm; snow depths cm; )

Readings taken at 0900 and 1800 UTC. Where the NIGHT maximum

or DAY minimum are significantly different from figures hereunder, this will be noted in the accompanying text summary. There are now two mean daily temperatures shown: the first is the mean of the average day maximum and average night minimum (A), and the second is the average of the 24hr maximum and 24hr minimum (B .. as kept formerly) .. the anomalies are shown for this latter figure from 1971-2000 estimated Long Term Averages. Rainfall is credited to the 24hr day beginning 0900 UTC.

=================================

TEMPERATURES ETC.

Highest day maximum (date):... 11.2(14)

Highest 24hr maximum (date):.. 11.2(14)

Lowest night minimum (date):...-03.7(11)

Lowest 24hr minimum (date):...-03.7(11)

Lowest overnight grass minimum (date):... -05.5(10)

[ number of days grass minimum < 0degC: ... 12 ]

[ Lowest day maximum (date):... -00.3(02)]

[ Highest night minimum (date):... 07.2(13)]

A. Mean Day (09-18Z) maximum: ... 06.1

A. Mean Night (18-09Z) minimum: ... 01.9

A. Mean of Day Max & Night min: ... 04.0

B. Mean 24hr maximum:... 06.1

B. Mean 24hr minimum:... 01.1

B. Mean of 24hr max & min:... 03.6 [-0.7 anomaly on eLTA of 4.3degC]

(data below relate to 24 hr day beginning 09Z on date given)

Nr of days minimum at 09UTC <0.0degC:10[dates: 02-05,10-12,18,24-25]

Nr of days maximum at 09UTC >=21degC:00

Nr of days maximum at 09UTC >=25degC:00

Nr of days maximum at 09UTC >=30degC:00

(Notes relating to temperature & allied observations:

2nd: Ice Day – 24hr maximum –0.3degC;)

=================================

PRECIPITATION (PPN/mm)

Total rainfall/melted snow etc:... 54.3 [123% of eLTA of 44mm]

Highest 24hr total:............... 13.0(19)

No. days PPN total >= 0.2:11

No. days PPN total >= 1.0:09

No. days PPN total >=10.0:02

No. days PPN total >=25.0:00

(Notes relating to precipitation & allied observations:

3rd: is(very slight) 11-13Z;

7th: ir(very light) ~09Z;

7th/8th: r(slight)/r from ~1810Z to ~08/02Z, with bulk of same coming from ~23Z: wettest day since 16th January;

12th: r(slight),ocnl r from ~0230Z, bec r(R) by 0530Z; rain continued, mainly light ocnl moderate until (at least) 18Z, then mainly light, finally petering out between 21 & 22Z;

14th: ir/d(light) early hours onwards, dying out just after 09Z; pr(slight / moderate) ~16/1630Z;

14th/15th: r(R) from ~23Z to ~0530Z;

15th: ir(slight) early evening;

16th: pr/r 06-0830Z; pr(slight)/pr from late morning with small hail in pr/R 1145-1200Z;

16th/17th: pr(slight, ocnl moderate) overnight;

19th: r(slight) from 1150Z, soon r, with period r/R during afternoon. Through evening, r bec. r(slight), dying out around midnight;

20th: prq (squally shower) ~1515Z, but only yielded a trace of rainfall: other pr(slight) ~16Z;

20th/21st: pr(slight) overnight & morning;

21st: phsr(slight, isolated moderate) from late morning – mix snow pellets / small hail / rain;

21st/22nd: ocnl dr(slight ocnl moderate), isol rs(slight) overnight;

22nd: ir(slight), ocnl moderate, much of day;

23rd: s(slight) began 0830Z, soon rs(slight): continued without a break until (at least 18Z), rs/s(slight), ocnl rs in morning & rs/r(slight), ocnl rs in afternoon, bec light/sporadic evening, dying out by 21Z;

24th: sh(snow grains)/s(very light) from ~06Z, then periods ps/ph(snow/ snow pellets) – light but enough to cover roofs, some grass surfaces etc. Not counting for 09Z snow cover though;

26th: sh(snow grains)/rs(both mainly slight) since ~06Z, but sh(mod. snow grains)~09Z, bec. light then ceasing ~0930Z: a light pr ~1030Z;

27th: very light pr early afternoon;

28th: r(slight), ocnl r short-period early hours; ps(very light) ~1530 & 1715Z; phsq (snow pellets/snow/squall) 1740-1750Z, bec. ph(slight) by 1755Z;

=================================

OTHER TOTALS

Number of days thunder heard: (dates).. 00

Number of days hail < 0.5cm diameter:.. 03

Number of days hail >=0.5cm diameter:.. 00

Number of days snow/rain & snow:....... 07

Number of days snow lying at 09UTC:.... 00

Deepest snow cover (date,s):........... -

Number of days fog (visibility < 1km @ 09UTC).. 02

=================================

Additional comments on the weather in February, 2006

4th/5th: evening haze quickly thickened as day-time Sc cleared suddenly 17-1730Z: fog (<1km vis.) by 04/22Z, with vis <500m by 05/05Z & soon ~200m thereafter;

9th: periods during day when relative humidity <<60%;

18th: m > f ~0730Z, down to ~200m for a time, clearing above 1km ~1130Z;

[thunder]

(none)

[snow]

3rd: is(very slight) 11-13Z: no impact upon surface or visibility – just a few flakes at a time;

21st: scrappy showers of snow pellets (with small hail & rain) – the rain the main element: occurred from late morning. Temporary accumulation in a few spots from one such ~1545Z

22nd: some very short-lived sleet episodes early hours;

23rd: s/rs(slight) from 0830Z then continuous rs/s(slight) morning ocnl rs, and continuous rs/r(slight), ocnl rs afternoon bec light/sporadic evening, dying out by 21Z;

24th: sh(snow grains)/s(very light) from ~06Z, then periods ps/ph(snow/ snow pellets) – light but enough to cover roofs, some grass surfaces etc. Not counting for 09Z snow cover though;

26th: sh(snow grains)/rs(both mainly slight) since ~06Z, but sh(mod. snow grains)~09Z bec. light then ceasing ~0930Z: a light pr ~1030Z;

28th: ps(very light) ~1530 & 1715Z; phsq (moderate shower snow pellets / snow / squall) 1740-1750Z, bec. ph(slight) by 1755Z: a slight, or shallow, accumulation on some grass surfaces;

... these data can also be viewed at:-

http://homepage.ntlworld.com/booty.weather/metinfo/wxdata/climintro.htm

Tn Tx Tg RR Tn Tx RR RR24hr Remark code (below)

(09Z) (09Z) (09Z)(18-09Z) (18Z) (18Z) (09-18Z) (from 09Z today)

01 00.3 02.7 00.2 - 00.3 01.0 - - -

02 -01.6 00.6 -01.6 - -01.6 -00.3 - -

03 -02.5 -00.7 -02.5 - -02.4 01.1 tr tr A

04 01.1 02.1 01.0 - 02.1 05.3 - - B

05 -00.3 04.1 -03.3 - 00.3 06.3 - - C

06 04.3 05.8 03.8 - 04.4 07.2 - tr D

07 06.2 07.1 05.5 tr 07.1 08.6 tr 02.9

08 02.8 07.9 00.8 02.9 03.7 08.5 - -

09 01.2 06.0 -00.8 - 02.4 04.9 - -

10 -03.2 02.4 -05.5 - -01.8 05.4 - -

11 -03.7 01.7 -05.4 - -02.3 05.4 - 07.7

12 02.1 04.4 -02.2 07.7 04.4 08.8 05.2 05.5

13 07.2 08.4 05.7 00.3 07.8 10.3 - 00.1

14 05.6 08.7 05.2 00.1 05.7 11.2 00.1 11.9 E

15 06.6 08.7 05.0 11.8 08.4 11.0 - 02.8

16 05.0 08.4 03.6 02.8 05.0 08.0 00.9 01.2

17 04.5 06.3 03.1 00.3 05.4 09.9 - tr

18 -00.6 05.7 -03.3 tr(w) 01.3 06.8 - - F

19 03.7 05.9 01.1 - 05.3 06.2 07.2 13.0

20 04.0 05.6 03.3 05.8 03.8 06.5 tr 00.1

21 01.4 03.8 -00.4 00.1 02.4 05.4 00.5 01.1

22 02.4 03.5 01.9 00.6 02.3 03.1 00.6 00.6

23 00.9 02.3 00.2 tr 01.0 02.1 06.3 06.8 (note amend rain)

24 -00.1 01.2 -00.8 00.5 -00.1 03.4 - - G

25 01.4 02.8 00.5 - 01.6 06.6 - tr

26 01.3 03.9 00.5 tr 01.3 06.3 tr tr

27 01.2 04.6 -02.2 - 02.9 05.8 tr 00.5

28 01.1 04.5 -00.6 00.5 00.6 05.4 00.1 00.1

Remarks:

A. day min.(-2.4), also 24hr min 4th, occurred 03/09Z

B. night max.(2.1), also 24hr max 3rd, occurred 04/09Z

C. day min.(0.3), also 24hr min 6th, occurred 05/09Z

D. day min.(4.4), also 24hr min 7th, occurred 06/09Z

E. day min.(5.7), also 24hr min 15th, occurred 14/09Z

F. PPN 17/18Z-18/09Z from overnight dew

G. day min.(-0.1), also 24hr min 25th, occurred 24/09Z

Number of occasions (24hr periods) THIS YEAR (2006)

maximum temperature >= 21degC (70degF) = 00

minimum temperature >= 16degC (61degF) = 00

[Summary re: Winter 2005/06]

TEMPERATURE:

MEAN MAX(ANOMALY) MEAN MIN(ANOMALY) 24HR MEAN

DEC: 7.1 (-0.5) 1.3 (-1.7) 4.2 (-1.1)

JAN: 6.7 (-0.1) 2.5 (+0.9) 4.6 (+0.4)

FEB: 6.1 (-1.2) 1.1 (-0.2) 3.6 (-0.7)

SEAS: 6.6 (-0.6) 1.6 (-0.4) 4.1 (-0.5)

Rolling 12 month temperature anomaly: +0.6 (was +0.7)

[ Precipitation ]

February total = 54.3 [123% of eLTA 1971-2000]

Most anomalously 'wet' month since October 2004 (166%), but only the wettest month by absolute value since December 2005.

This ends a run of 3 dry Februarys (2003-2005)

'Standard' winter precipitation:

TOTAL ANOMALY

DEC: 61.2 87%

JAN: 24.4 37%

FEB: 54.3 123%

WINTER: 139.9 78%

The second dry winter in a row, though last winter was much drier with an anomaly of 55%

The average precipitation for extended period Nov-Feb (winter 71/72 to 00/01 incl): 239mm

Last winter, the total for those 4 months was: 139mm (58%)

This winter, the total for those 4 months has been: 201.3 mm (84%)

Rolling 12 month rainfall anomaly: 86%

Rolling 24 month rainfall anomaly: 86%

Some notes / comparison regarding the standard 'climatological' winter (2005/06):

No days of 09-09Z air frost = 31, the same number as in winter 2000/01

No days with snow-lying at 09Z = 0: also, there were NO occasions with snow-lying (>50% cover) at ANY time over these past 3 months – a truly remarkable situation for a nominally colder-than-average season. February in particular was a 'cold, wet' month (see above), but none of the poor snow events managed even a temporary cover.

No days with snow/sleet = 13: last year, with an 'all-winter' temperature anomaly of +0.6C, we also had 13 days ( 3 of which produced a 'proper' snow cover ); this year, none of the events produced a climatological snow cover, despite the overall anomaly of –0.5C.

Average temperature winter overall: 4.1°C (-0.5 on 1971-2000 eLTA); integrating with the adjacent Easthampstead Park record, by anomaly this winter just gone had a similar value to 2002/03 (also –0.5). To find a colder winter, then you have to go back to winter 1996/97 (marginally), but for a winter notably colder than these three, then back to 1995/96 (-1.2).

The 1971-2000 LTA is, I believe, regarded as ~0.4C higher than 1961-1990 (the 'standard' reference period the Met Office use), therefore it could be argued that this winter just ended has been 'around average' as regards temperature.

Since 1990, 6 winters have had negative anomalies (1990/91 [-1.4], 1991/92 [-0.2], 1995/96 [-1.2], 1996/97 [-0.6], 2002/03 [-0.5] & 2005/06 [-0.5].

Martin.