Summary for February 2007

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

HEADLINE: COLD SNAP, SOME SNOW 4TH-9TH; ELSE CYCLONIC, MILD & VERY WET

(last updated: 01/1600 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; )

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

TEMPERATURES ETC.

Highest day maximum (date):... 11.7(27)

Highest 24hr maximum (date):.. 11.7(27)

Lowest night minimum (date):...-06.0(07)

Lowest 24hr minimum (date):...-06.0(07)

Lowest overnight grass minimum (date):...-06.9(07)

[ number of days grass minimum < 0degC: ... 09 ]

[ Lowest day maximum (date):... 01.6(07)]

[ Highest night minimum (date):... 08.4(20)]

A. Mean Day (09-18Z) maximum: ... 08.7

A. Mean Night (18-09Z) minimum: ... 04.0

A. Mean of Day Max & Night min: ... 06.3

B. Mean 24hr maximum:... 08.8

B. Mean 24hr minimum:... 03.3

B. Mean of 24hr max & min:... 06.1 [+1.8 anomaly wrt eLTA of 4.3degC]

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

Nr of days minimum at 09UTC <0.0degC:07[dates: 03-09]

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:

none)

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

PRECIPITATION (PPN/mm)

Total rainfall/melted snow etc:... 98.5 [224% of eLTA of 44mm]

Highest 24hr total:............... 16.8(13)

No. days PPN total >= 0.2:19

No. days PPN total >= 1.0:16

No. days PPN total >=10.0:01

No. days PPN total >=25.0:00

(Notes relating to precipitation & allied observations:

2nd: id(slight) from early hours, with short-period r(slight) 0800-0830Z;

5th: id(very light) ~08Z; r(slight) from ~1745Z – 19Z;

8th: s(slight)/s (iS) from ~0230Z, mainly slight by 0530Z, but temporary moderate bursts before finally ceasing by ~1120Z: pr(slight/moderate) and/or prs(mainly slight) thereafter bec. r(slight)/ocnl rs(slight), csd by 08/20Z;

9th: s(slight) 0925Z, slowly becoming rs(slight, ocnl moderate/tempo s(slight) again for a short time) through morning, then r(slight) by 13Z, continued much of afternoon, csd by ~ 1715Z;

10th: r(slight)/r since ~03Z, csd by 1015Z: r/d(slight), ocnl r, 1620 – 1815Z;

10th/11th: sporadic rain (mainly light) late evening 10th/early hours 11th, then r/R/q between 04 & 05Z;

11th: pr(slight) 0840Z-0855Z & also PM (often few droplets only);

11th/12th: periods r(slight)/r evening & overnight;

12th: ir(slight)/r AM -> ir/pr(slight) PM;

13th: r(slight) 1725Z, becoming r(R) soon after 18Z, lasting through the night (13th/14th) & into the morning 14th, csd ~0945Z;

15th/16th: r(slight)/r between 23Z & 02Z;

16th: ir/pr (medium-level shower)~12Z, pr(slight) ~mid-afternoon;

19th: id/r(mainly light) after 01Z, csd by 07Z;

19th/20th: r(slight), ocnl r, from 2130Z to ~04Z, then id/r(very light), ceased by 08Z;

20th: r(slight) between 1310-1320Z;

20th/21st: r(slight)/r from ~23Z to ~0430Z. pr ~21/0620Z;

21st/22nd: r(slight)/r off and on (more the latter), from late PM 21st until early PM 22nd, then id/r until ceased ~22/1530Z;

23rd: r/R between 00 & 01Z. pr ~ 0555Z. pr(slight), isol pr through day. r(slight) 1750Z.

23rd/24th: at least two periods of r/R evening & overnight, ceased by 0600Z;

24th: dr 1115-1125Z; pr(mainly slight) thereafter, but dry after 15Z;

24th/25th: ir(slight) early evening -> r(R) between 24/2330Z & 25/02Z. Sporadic r(slight) 06Z – 08Z;

25th: several pr during afternoon;

26th: sporadic/light rain after midnight, with period r 0710-0740Z;

27th: r(R) after ~0230Z, becoming dr(slight/moderate) by 0530Z: intermittent dr(slight) until 1505Z, then r(R) until 1650Z, then a couple of scrappy pr(slight) to 1750Z;

27th/28th: sporadic showers – mainly light;

28th: two pr(R/h/<5mm) between 0715 & 0815Z, hail element not significant, and heavy rain very short-lived. Thereafter, frequent pr(isol R) through day, with isol tl(slight) ~1317Z & 1356Z (single-clap affairs) until 14Z, then mainly dry;

28th Feb/1st Mar: r(slight)/r between ~23Z & ~01Z (rainfall credited to February))

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OTHER TOTALS

Number of days thunder heard: (dates).. 01 (28)

Number of days hail < 0.5cm diameter:.. 01

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

Number of days snow/rain & snow:....... 02

Number of days snow lying at 09UTC:.... 01

Deepest snow cover in cm (date,s):..... 06(08)

Number of days fog (visibility < 1km @ 09UTC).. 00

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

Additional comments on the weather in February, 2007

4th: if/jf/8St temporarily between 11 & 13Z (fog/low cloud from elsewhere advecting across area before clearing).

28th: two pr(R/h/<5mm) between 0715 & 0815Z, hail element insignificant.

[thunder]

28th: amongst a series of frequent (09-14Z) heavy rain showers, two events with single-claps of thunder (CC/IC – extended 'rumbles'); 1317 & 1356Z.

[snow]

8th: s(slight)/s (iS) from ~0230Z, mainly slight by 0530Z, when depth 6cm grass, 4cm hard/concrete surfaces; at 09Z climatological hour, average depth over grass 6cm, with maxima 8cm: 4 or 5cm concrete/tarmac – local traffic moving. Further light, ocnl moderate snow until ~1120Z, then light rain/snow showers through afternoon. Snow depth over grass down to 4cm by 15Z, with hard surfaces increasingly clear of snow, & 3cm / increasingly patchy by 18Z. (9th: snow covering less than half-the-ground/depth over grass ~2cm).

9th: s(slight) 0925Z, slowly becoming rs(slight, ocnl moderate/short period s(slight) again through morning, then r(slight) by 13Z: no impact on state of ground. Snow cover this morning (09Z) <50%, and across wider local area, 15-20% generally: snow in isolated patches by 18Z.

... 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 06.0 08.5 02.7 - 08.2 11.6 - 00.2 A

02 05.9 08.2 01.4 00.2 08.2 11.0 - -

03 -00.9 09.4 -03.3 - 00.2 08.7 - -

04 -02.3 04.6 -04.4 - -01.5 04.6 - tr B

05 00.7 04.0 -01.7 tr 01.1 04.1 tr tr

06 -01.8 04.0 -04.7 tr -01.5 03.5 - -

07 -06.0 00.5 -06.9 - -04.8 01.6 - 06.2 C

08 -01.8 01.2 -04.6 06.2 00.5 03.4 02.8 02.9 D

09 -01.0 03.3 -04.4 00.1 00.6 04.3 01.5 06.9 EF

10 04.3 06.4 03.2 05.4 05.1 09.0 02.5 07.9 GH

11 06.7 09.5 04.3 05.4 07.0 10.2 tr 06.2 IJ

12 07.2 09.0 05.2 06.2 07.5 09.3 03.0 03.0

13 05.4 07.6 02.2 tr 05.8 08.7 tr 16.8 K

14 07.1 08.1 06.2 16.8 06.5 08.6 00.1 00.1

15 01.7 06.5 -01.4 tr(w) 06.5 10.4 - 00.7

16 06.1 08.2 03.4 00.7 06.7 11.0 00.1 00.1

17 01.7 09.2 -00.9 - 03.2 10.1 - - L

18 06.3 09.2 05.7 - 06.8 08.0 - 00.1

19 06.7 07.9 06.2 00.1 07.9 10.8 - 01.0 M

20 08.4 09.0 07.1 01.0 09.0 11.0 tr 05.0

21 07.8 10.3 05.6 05.0 08.0 10.5 - 00.7

22 07.2 08.4 04.7 00.7 08.4 09.6 02.9 05.5

23 07.3 09.5 05.0 02.6 08.7 10.7 00.6 04.8

24 07.8 09.5 06.6 04.2 08.5 11.5 00.1 04.0

25 05.1 09.2 03.7 03.9 06.1 09.8 04.2 04.9 N

26 07.2 08.0 05.4 00.7 07.4 09.7 - 05.4

27 04.0 08.6 01.1 05.4 08.6 11.7 03.6 06.5 O

28 05.9 11.3 04.0 02.9 07.1 10.6 07.8 09.6

Readings taken at 0900 and 1800 UTC. Where the NIGHT maximum or DAY minimum are significantly different from 24hr values, this will be noted in the listing against a 'Remarks' letter. There are two mean 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) .. 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.

Remarks:

A. The 24hr min for the 1st (2.8) occurred at 31/09Z Jan

B. day min.(-1.5), also 24hr min 5th, occurred 04/09Z

C. day min.(-4.8), also 24hr min 8th, occurred 07/09Z

D. All PPN 18-09Z from melted snowfall

E. grass min. thermo. reading over the lawn snow cover

F. day min.(0.6), also 24hr min 10th, occurred 09/09Z

G. night max.(6.4), also 24hr max 9th, occurred second half of night

H. day min.(5.1), also 24hr min 11th, occurred 10/09Z

I. night max.(9.5), also 24hr max 10th, occurred overnight

J. day min.(7.0), also 24hr min 12th, occurred 11/09Z

K. day min.(5.8), also 24hr min 14th, occurred 13/09Z

L. day min.(3.2), also 24hr min 18th, occurred 17/09Z

M. day min.(7.9), also 24hr min 20th, occurred 19/09Z

N. day min.(6.1), also 24hr min 26th, occurred 25/09Z

O. night minima occurred first-half of evening

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Number of occasions (24hr periods) THIS YEAR (2007)

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

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

Rolling 12 month temperature anomaly: +1.8 (was +1.6 end last month)

This is now comfortably (it was marginal last month) the greatest +ve 12-month temperature anomaly since the series start in 1971.

Rolling 12 month rainfall: 121% of eLTA (was 115% end last month)

Rolling 24 month rainfall: 103% of eLTA (was 98% end last month)

This is the wettest February since 1990 (112.3mm / highest in 1971-2007 set), and the second wettest February in that composite local series.

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[SOME WINTER NOTES]

Eden Winter Snow Index (cm days)

[November – March]

1998/1999: 0

1999/2000: 11

2000/2001: 10

2001/2002: 0

2002/2003: 18

2003/2004: 5

2004/2005: 9

2005/2006: 0

2006/2007: 7 (so far)

note that *last* year, when the mean winter-time temperature was close to average, we had little snow cover at all, let alone some at 09Z. This mild very winter, we have fared much better!

[TEMPERATURE]

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

DEC: 8.9 (+1.3) 4.5 (+1.5) 6.7 (+1.4)

JAN: 9.7 (+2.8) 4.9 (+3.3) 7.3 (+3.1)

FEB: 8.8 (+1.5) 3.3 (+2.0) 6.1 (+1.8)

SEAS: 9.1 (+1.9) 4.2 (+2.2) 6.7 (+2.1)

With this value (for the three months of winter), this is the warmest such season since 1989/1990 (anomaly +2.3C); this latter was also THE warmest winter in the dataset which begins 1971.

[ Precipitation ]

'Standard' winter precipitation:

TOTAL ANOMALY

DEC: 93.2 133%

JAN: 76.1 115%

FEB: 98.5 224%

WINTER: 267.8 149%

This is the wettest winter (DJF) since 2000/2001.

This has been the sixth consecutive month with rainfall %age >=10% above the LTA. Sequences of 6 or more consecutive months with above-average rainfall are not common within the last 35 years: prior to this one there were only two viz: 1994 September – 1995 February (6 months) & 2000 September – 2001 April (8 months).

For the period September – February, the rainfall total is 584.6mm, or 151% of the 1971-2000 average of those 6 months (388mm)