Summary for December 2004

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

HEADLINE:NOTABLY DRY TO MID-MONTH; UNSETTLED/COLDER THEREAFTER

(last updated: 01/0900 JANUARY)

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.

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TEMPERATURES ETC.

Highest day maximum (date):... 12.0(30)

Highest 24hr maximum (date):.. 12.0(30)

Lowest night minimum (date):... –03.2(20)

Lowest 24hr minimum (date):... –03.2(20)

Lowest overnight grass minimum (date):... –05.1(20)

[ number of days grass minimum < 0degC: ... 13 ]

[ Lowest day maximum (date):... 01.9(13)]

[ Highest night minimum (date):... 10.0(23)]

A. Mean Day (09-18Z) maximum: ... 07.3

A. Mean Night (18-09Z) minimum: ... 03.3

A. Mean of Day Max & Night min: ... 05.3

B. Mean 24hr maximum:... 07.9

B. Mean 24hr minimum:... 02.4

B. Mean of 24hr max & min:... 05.1 [-0.2 anomaly on eLTA of 05.3degC]

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

Nr of days minimum at 09UTC <0.0degC:08[dates: 01-02,11-12,20,26-28]

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)

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PRECIPITATION (PPN/mm)

Total rainfall/melted snow etc:... 49.4 [71% of eLTA of 70mm]

Highest 24hr total:............... 14.1(18)

No. days PPN total >= 0.2:10

No. days PPN total >= 1.0:06

No. days PPN total >=10.0:03

No. days PPN total >=25.0:00

(Notes relating to precipitation & allied observations:

8th: very light/intermittent rain from ~0830 to ~0915;

13th: very light d from ~1630Z;

13th/14th: ocnl dr(slight) overnight;

15th: ocnl r(slight) ~04Z-0730Z;

16th: ocnl r(mainly slight) from ~ 04Z; r(slight), ocnl r 0910Z-1140Z;

17th: r(slight)/r – since just before 05Z until ~1240Z, with short bursts r/R during late morning;

18th: pr(slight) ~0855Z; r(slight) began ~ 1730Z, continuing through much of night 18th/19th, with r(R) late evening 18th to early hours 19th, accompanied by strong NE wind;

20th: very light snow-grains fall (from SC) 0845-0900Z; r(slight) from 17Z until ~19Z;

22nd: r(slight), ocnl r from ~03Z to 09Z, then r(slight) until just before midday;

23rd: ir(slight/very) ~1430Z;

24th: ir(mainly slight) from ~1315Z until ~19Z;

27th/28th: r(R) 2330-0130, then Rhq(small hail) 0130-0145, with rain easing considerably, csd by 0330Z;

29th: ir(slight) PM;

31st: d/r(slight) several hours prior to 09Z, ceasing by 0915Z

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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:....... 01

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

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

Number of days fog (visibility < 1km @ 09UTC).. 01

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Additional comments on the weather in December, 2004

2nd/3rd: f(Fe) since ~02/22Z, clearing late AM 3rd;

8th/9th: f/F late PM 8th to early hrs 9th;

11th: if (07-08Z & again late morning;

20th/21st: f overnight from about 02Z to ~08Z;

28th: considerable fall of small hail (within heavy rain shaft) between 0130 and 0145Z: some appreciable rain-catch may have been lost due to hail blocking the gauge for a time, or via 'bounce-out' of the hail;

30th: hard (ex-cold) surfaces 'sweating' as dew points rise;

... 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 -00.2 03.9 -02.5 - 02.6 06.0 - - -

02 -00.1 04.9 -02.6 - 01.5 05.1 - tr

03 01.1 04.4 -01.7 tr 01.9 05.1 - - AB

04 03.9 06.3 01.4 - 06.3 09.6 - - C

05 06.5 08.7 04.3 - 08.0 10.6 - - D

06 08.5 09.2 06.9 - 08.8 11.0 - - E

07 04.3 08.6 01.7 - 05.5 08.7 - tr F

08 07.5 08.5 06.4 tr 08.1 08.9 tr tr

09 01.6 08.4 -00.9 - 02.2 05.1 - -

10 02.5 04.7 01.5 - 04.5 06.6 - -

11 -00.7 04.6 -02.7 - -00.4 04.1 - - G

12 04.3 06.5 04.3 - 04.3 05.7 - - H

13 01.4 04.3 01.3 - 01.5 01.9 tr 00.2 I

14 01.7 05.2 01.6 00.2 05.2 09.7 - 00.1 JK

15 09.1 10.1 08.1 00.1 08.8 11.2 - 01.1 L

16 08.1 10.6 05.1 01.1 07.7 10.7 01.8 05.7 M

17 06.1 07.7 04.6 03.9 05.3 06.4 10.4 10.4

18 02.2 05.1 -00.4 tr 04.3 07.2 tr 14.1

19 02.9 06.3 01.6 14.1 01.8 05.3 - tr

20 -03.2 01.6 -05.1 tr 01.1 05.0 00.2 00.3

21 01.4 04.6 -00.3 00.1 01.6 03.8 - 06.9

22 00.6 07.1 -01.3 06.9 07.1 11.0 00.1 00.1 NOP

23 10.0 11.4 08.5 - 10.2 11.7 tr tr Q

24 06.9 10.9 05.7 - 06.9 10.5 00.3 00.3

25 01.0 08.4 -00.5 tr 01.0 04.5 - -

26 -02.8 01.0 -04.5 - -02.6 02.7 tr(X) tr R X=hoarfrost

27 -02.5 00.3 -04.5 - -02.3 03.4 00.1(X) 10.0 S X=hoarfrost

28 02.1 07.6 00.1 09.9 02.1 05.5 - - T

29 01.3 03.7 -01.1 - 01.3 07.3 tr tr

30 07.3 10.4 07.0 - 09.6 12.0 - 00.2

31 08.5 10.1 06.8 00.2 08.6 11.7 tr tr U

Remarks:

A. tr of PPN from overnight wet fog

B. day min.(1.9), also 24hr min 4th, occurred 03/09Z

C. night max.(6.3), also 24hr max 3rd, occurred 04/09Z

D. day min.(8.0), also 24hr min 6th, occurred morning 5th

E. night max.(9.2) occurred 06/09Z

F. day min.(5.5), also 24hr min 8th, occurred 07/09Z

G. day min.(-0.4), also 24hr min 12th, occurred 11/09Z

H. night max.(6.5), also 24hr max 11th, occurred evening 11th

I. day min.(1.5), also 24hr min 14th, occurred during morning 13th

J. night max.(5.2), also 24hr max 13th, occurred 14/09Z

K. day min.(5.2), also 24hr min 15th, occurred 14/09Z

L. night max.(10.1), also 24hr max 14th, occurred 15/09Z

M. night max.(10.6), occurred 16/09Z

N. night max.(7.1), also 24hr max 21st, occurred 22/09Z

O. day max.(11.0) occurred 22/18Z – airmass change PM

P. day min.(7.1), also 24hr min 23rd, occurred 22/09Z

Q. night max.(11.4), also 24hr max 22nd, occurred late in night

R. day min.(-2.6), also 24hr min 27th, occurred 26/09Z

S. day min.(-2.3), also 24hr min 28th, occurred 27/09Z

T. night max.(7.6), also 24hr max 27th, occurred middle of night

U. night max.(10.1) occurred 31/09Z

Number of occasions (24hr periods) THIS YEAR (2004)

maximum temperature >= 21degC (70degF) = 80

minimum temperature >= 16degC (61degF) = 13

ANNUAL SUMMARY (2004)

TEMPERATURE:

Individual monthly (24hr) anomalies . . .

+1.2 +1.3 +0.0 +1.1 +1.0 +1.6 –0.3 +1.6 +1.5 +0.7 +1.0 -0.2

= +0.9degC

Individual monthly (24hr) average max:

8.0 8.0 10.0 14.3 18.3 22.1 22.4 23.4 19.8 14.0 10.3 7.9

+1.2 +0.7 +0.1 +1.4 +1.0 +2.0 –0.2 +1.5 +2.1 +0.4 +0.7 +0.3

= 14.9degC (+0.9)

Individual monthly (24hr) average min:

2.8 3.2 3.3 5.5 8.5 11.8 12.3 14.2 11.6 8.4 5.4 2.4

+1.2 +1.9 –0.1 +0.8 +1.0 +1.2 –0.4 +1.7 +0.8 +1.1 +1.0 –0.6

= 7.5degC (+0.8)

RAINFALL:

Individual monthly totals . . .

87.5 27.7 47.5 83.5 52.0 25.9 39.0 67.1 27.3 124.8 41.0 49.4

= 672.7mm (95%)

Individual monthly anomalies . . .

133% 63% 91% 161% 90% 47% 87% 124% 41% 166% 62% 71%