Summary for January 2007

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HEADLINE: EXCEPTIONALLY MILD. WET/WINDY TO 20TH; COLD, SOME SNOW 21ST-26TH

(last updated: 01/1600 FEBRUARY)

[ NB: extended period of missing or estimated data 6th – 9th ]

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; )

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TEMPERATURES ETC.

Highest day maximum (date):... 13.5(18)

Highest 24hr maximum (date):.. 13.5(18)

Lowest night minimum (date):...-02.4(26)

Lowest 24hr minimum (date):...-02.4(26)

Lowest overnight grass minimum (date):...-04.0(24)

[ number of days grass minimum < 0degC: ... 07 ]

[ Lowest day maximum (date):... 03.3(23)]

[ Highest night minimum (date):... 12.0(09)]

A. Mean Day (09-18Z) maximum: ... 09.4

A. Mean Night (18-09Z) minimum: ... 05.2

A. Mean of Day Max & Night min: ... 07.3

B. Mean 24hr maximum:... 09.7

B. Mean 24hr minimum:... 04.9

B. Mean of 24hr max & min:... 07.3 [+3.1 anomaly wrt eLTA of 4.2degC]

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

Nr of days minimum at 09UTC <0.0degC:03[dates: 24-26]

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:

25th/26th: sharp fall of temperature evening 25th, temperature rising slowly towards end of the night;)

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PRECIPITATION (PPN/mm)

Total rainfall/melted snow etc:... 076.1 [115% of eLTA of 66mm]

Highest 24hr total:............... 13.8(06)

No. days PPN total >= 0.2:21

No. days PPN total >= 1.0:13

No. days PPN total >=10.0:03

No. days PPN total >=25.0:00

(Notes relating to precipitation & allied observations:

1st: r(R) 1610-1745Z, then r(slight) until ~1915Z;

2nd: pr(very slight) late morning;

2nd/3rd: sporadic, very light drizzle/rain overnight, but . . .

3rd: persistent r(slight), ocnl r, from 0830Z to 10Z, then id/ir(slight) until at least 18Z – r(R) between 1845 & 2105Z;

3rd/4th: r/R for short-periods overnight;

4th/5th: ir(slight) overnight;

5th: ocnl d/r(slight) PM;

6th: r(slight), ocnl r/dr, from ~06Z, becoming r/R much of morning / early afternoon, clearing mid-afternoon;

6th/7th: r/d(slight), especially late in night;

7th: id/r(very slight/lengthy dry spells);

7th/8th: period r(slight)/r/d evening & night;

8th: d/r(slight) from ~1115Z, period continuous, bec. intermittent through evening;

9th: id(slight);

9th/10th: r(latterly R) ~09/23Z - ~10/0730Z, then r -> r(slight) by mid-morning/10th, then idr(slight), ceased by ~1130Z;

11th: r(slight)/dr(slight)/briefly r 03Z – 12Z, then after pr(slight) early PM, mainly dry;

12th: ir(very slight) early PM;

12th/13th: id/r (sporadic/light) overnight;

13th: pr(slight) 09Z, then id/ir(both mainly slight) until ~1430Z; period rain 1920-2030, with r/R between 2005 & 2020Z;

15th: id/r(few spots only) latter part of night;

16th: r(slight), ocnl r, from ~03Z through much of day (to 17Z), with ocnl dr;

16th/17th: periods of rain overnight, becoming persistent by 17/07Z, ocnl heavy ~08Z, csd by 0818Z, the re-started (mainly slight) ~17/0830Z, csd by 17/1130Z;

17th/18th: rain much of evening/overnight, with r/R (and rising wind) second-half;

18th: dr/r(slight, ocnl moderate) from dawn until 1315Z (cold-frontal passage): pr(slight) ~1515Z;

18th/19th: period rain (short-period moderate), late evening/around midnight;

19th: d(slight)/(mist/warm front) ~19Z, then sporadic d/r(slight) through night (19th/20th) until . . .

20th: r(slight)/r between 0530Z & 0800Z; pr(slight/moderate) 1140-1200Z & very light shower mid-afternoon;

20th/21st: sporadic rain(ocnl moderate/squally) overnight;

21st: pr(slight/moderate) from 0800Z, but overwhelming bulk of day dry. rs(very light) from ~1745Z;

22nd: r(slight) from ~0745Z to ~1130Z, with short-periods moderate r and/or rs(slight);

24th: period s(slight/moderate) after 03Z, csd ~0630Z; irs(very slight) 0925-0930Z;

25th: is(few flakes only/decaying Cu)~0915Z;

26th: is(few flakes only) -> id(very light) 0600-0800Z; pr(slight) ~0845/0900Z & ~16Z;

29th: id(very light) between 10 & 11Z; )

30th: id/r(slight)~06Z; id(very slight) before midday;)

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OTHER TOTALS

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

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

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

Number of days snow/rain & snow:....... 05

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

Deepest snow cover (date,s):........... 01(24)

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

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Additional comments on the weather in January, 2007

1st: short burst small hail amongst moderate/heavy rainfall ~05Z

18th: WSW wind rising second-half of night (17th/18th), up to F6/7 by 07Z and ocnl F8 (with sudden squalls) between 13 & 16Z

30th: short period fog early hours – lifted by dawn

[thunder]

Nil

[snow]

21st: very light rain/snow ~1745Z

22nd: a little rain/snow mixed ~1015-1100Z

24th: period s(slight, ocnl moderate), after 03Z, csd by 0630Z: depth at 06Z, fairly even (and complete) at 1.5 to 2.0cm, but by 09Z climatological hour, 'black' surfaces clear, & with settling of new snow, average depth at this time 1cm (rainfall yield at 09Z = 1.5mm): bulk of snow melted by 12Z

25th: is(few flakes only/decaying Cu)~0915Z

26th: is(few flakes only/PPN started into cold air)~0600Z, soon drizzle

... 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 05.0 12.2 03.4 05.5 05.4 09.0 07.7 08.3 -

02 04.0 05.7 03.3 00.6 05.7 08.6 tr 00.2

03 03.9 09.2 00.2 00.2 09.2 11.1 00.1 03.3 A

04 08.2 10.9 06.0 03.2 08.3 10.0 - tr

05 07.9 08.9 06.0 tr 08.6 11.3 00.2 00.6

06 04.4 11.2 00.8 00.4 (06.5)(08.5) 13.8 (13.8) B

07 05.3 (09.9) 02.9 (tr) (09.0)(11.2)(tr) (03.9) B C

08 (06.0)(10.2)(03.3)(03.9) (06.3)(12.5)(01.3) (01.3) B D

09 (12.0)(12.8)(10.0)(tr) (12.1) 13.1 (tr) 13.4 B E

10 09.8 (13.0) 08.9 13.4 05.8 10.5 tr 00.4 F

11 04.5 10.6 01.9 00.4 09.4 12.2 00.8 00.8 GHI

12 07.2 09.4 04.5 - 09.4 13.0 tr 00.1 J

13 09.8 12.2 08.7 00.1 10.2 11.3 00.2 02.1

14 03.4 10.5 00.1 01.9 03.6 09.0 - tr K

15 04.7 07.9 01.0 tr 07.4 09.5 - 02.2 LM

16 07.9 10.7 06.3 02.2 10.2 10.9 03.6 06.7 N

17 09.7 11.4 07.4 03.1 07.9 10.1 02.7 10.6 O

18 07.0 12.4 07.6 07.9 10.4 13.5 01.9 02.5 P

19 09.7 12.7 07.1 00.6 10.0 12.6 - 02.6

20 08.2 12.8 07.5 02.6 07.2 09.5 00.5 00.6 Q

21 04.5 07.2 01.8 00.1 05.1 07.6 00.4 00.5

22 01.9 05.8 -01.9 00.1 03.4 05.4 00.5 00.5

23 00.2 03.7 -02.2 - 00.2 03.3 - 01.5

24 -01.4 00.9 -04.0 01.5 00.8 03.6 tr tr R

25 -00.6 02.1 -02.7 - -00.1 03.6 tr tr

26 –02.4 01.4 -03.5 tr 01.4 06.8 tr tr S

27 02.6 06.2 -01.1 - 03.2 08.5 - - T

28 03.9 07.5 00.4 - 05.3 09.0 - - U

29 07.2 08.3 05.8 - 07.4 09.6 tr 00.2

30 06.5 08.5 05.7 00.2 06.5 07.8 tr tr

31 01.6 07.1 -01.1 - 02.8 10.0 - - V

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. night max.(9.2), also 24hr max 2nd, occurred 03/09Z

B. missing data 6th – 9th fitted / interpolated etc., with considerable help from data supplied by Clive Temperton (Bracknell COL site nearby)

C. night max.(9.9 estimated), was also 24hr max 6th

D. day min.(6.3 estimated), also 24hr min 9th occurred 08/09Z

E. night max.(12.8 estimated), also 24hr max 8th, occurred overnight

F. night max.(13.0) covers the period 21-09Z (not the usual 18-09Z)

G. night min.(4.5) occurred mid-evening, with strong rise of temperature overnight.

H. night max.(10.6), also 24hr max 10th, occurred 11/09Z

I. day max.(12.2) occurred before 12Z

J. day min.(9.4), also 24hr min 13th, occurred 09Z

K. day min.(3.6), also 24hr min 15th, occurred 09Z

L. trace a combination of (mainly) early dew deposit & a few droplets of rain/drizzle late in the night.

M. day min.(7.4), also 24hr min 16th, occurred between 09 & 10Z 15th

N. night max.(10.7), also 24hr max 15th, occurred second half of night

O. night max.(11.4), also 24hr max 16th, occurred sometime late evening – early hours.

P. night max.(12.4), also 24hr max 17th, occurred 09Z/18th

Q. night max.(12.8), also 24hr max 19th, occurred evening 19th

R. all PPN recorded 18-09 from melted overnight snow (1 cm average at 09Z, but up to 2cm at 06Z)

S. night minima occurred before midnight – slow rise in temperature thereafter

T. day min.(3.2), also the 24hr min 28th, occurred 27/09Z

U. day min.(5.3), also the 24hr min 29th, occurred 28/09Z

V. day min.(2.8), also the 24hr min 1st Feb, occurred 31/09Z

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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: +1.6 (was +1.4 end last month)

Rolling 12 month rainfall: 115% of eLTA (was 108% end last month)

Rolling 24 month rainfall: 98% of eLTA (was 94% end last month)

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[TEMPERATURE]

(As of 01/0900Z FEB):

Mean (24hr) temperature 7.3ºC(+3.1degC/1971-2000 eLTA).

Using a composite local record (1971 onwards), this value comfortably exceedS the previous warmest Januarys in this series (1990 & 1975/both 6.8ºC).

[ Of these two previous 'warmest' Januarys, 1975 was followed by a February that was roughly 'average' as regards temperature, whilst 1990 was followed by the warmest February AND the warmest March in the series.

In addition, there were two other Januarys with mean24hr temperature equal to or greater than 1sd above the mean: 1983 & 1993. 1983 was followed by a February *much* colder than average (and of course colder than January), with an anomaly of –2.5C, and 1993 had a February with temperature overall close to average.]

Over the past 8 months, 3 have been the warmest in their respective monthly sets (July, September & January), with July 2006 being * the * warmest month in the entire series. Two others were 'runners-up': June & October 2006 being the second-warmest such-named months in the series.

The 'rolling' 12-month temperature anomaly is currently +1.59C, with 8 (out of 12) months having a positive deviation from mean exceeding 1degC.

In a composite local record covering the period 1971 onwards, the previous 'any-12 month' highest +ve anomalies were: +1.47C (12 months to April 1990) and +1.58C (12 months to October 1995): we have therefore (just) had our warmest 12 month period since 1971.

Currently (end January), the winter anomaly is +2.3degC.

[PRECIPITATION]

Wettest January since 2004.

Fifth month in a row with PPN >=110% of LTA

See rolling figures above

Most January days with rain/snow or snow (5) since we started observing here in 2000: the previous highest was 2003 with 4 days and a maximum 09Z depth of 5cm; this time (24th), just one event produced a 'proper' snow cover - we had an 09Z depth of 1cm (maximum 2cm a couple of hours previously) which had virtually melted away by midday.

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