Summary for December 2005

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

HEADLINE:CYCLONIC/WET START, THEN ANTICYCLONIC, MAINLY DRY: WINTRY END

(last updated: 06/1000 JANUARY – AMENDMENT FOR MIN TEMP 27TH)

[ nb: BREAK IN OBSERVATIONS FROM 26/0900 TO 29/0900 – ESTIMATED DATA ]

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):... 11.6(16)

Highest 24hr maximum (date):.. 11.6(16)

Lowest night minimum (date):... -04.7(18)

Lowest 24hr minimum (date):... -04.7(18)

Lowest overnight grass minimum (date):...-06.0(18)

[ number of days grass minimum < 0degC: ... 16 ]

[ Lowest day maximum (date):... -00.7(29)]

[ Highest night minimum (date):... 07.7(23)]

A. Mean Day (09-18Z) maximum: ... 06.7

A. Mean Night (18-09Z) minimum: ... 02.3

A. Mean of Day Max & Night min: ... 04.5

B. Mean 24hr maximum:... 07.1

B. Mean 24hr minimum:... 01.3

B. Mean of 24hr max & min:... 04.2 [-1.1 anomaly on eLTA of 5.3degC]

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

Nr of days minimum at 09UTC <0.0degC:13[dates: 07,10-12,17-20,26-30]

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:

29th: the day max. of –0.7degC was due to lack of insolation; no assistance from a snow cover – as in previous occasions of low day maxima here.)

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PRECIPITATION (PPN/mm)

Total rainfall/melted snow etc:... 61.2 [87% of eLTA of 70mm]

Highest 24hr total:............... 27.0(01)

No. days PPN total >= 0.2:11

No. days PPN total >= 1.0:07

No. days PPN total >=10.0:02

No. days PPN total >=25.0:01

Notes relating to precipitation & allied observations:

30th Nov/1st: overnight dr(mainly light) – credited to November record;

1st: r(slight), ocnl r, 0920Z - ~ 12Z; r(R) 1555Z-1725Z, otherwise ocnl d/r (slight); r(R) mid-evening onwards ->

1st/2nd: r(R) much of night, bec. r/r(slight) by 0630Z, csd by 07Z.

2nd: pr(R) from 0810-0840Z, then a showery day & evening, ocnl moderate, with tl(slight)/single-clap/~1045Z;

3rd: mainly light pr early hours & 08-0820Z; further light rain showers during day;

4th: ocnl r early hours;

5th: light rain ~12Z;

6th: dr(slight) 1130-1230Z; dr(slight) 1550-1600Z; r(slight)/r ~ 1630Z;

7th: ir(slight) from ~16Z; r/R from ~1930Z to late evening; idr(slight) thereafter until late morning 8th;

8th/9th: heavy dewfall evening/night, with period wet fog contributed to 0.1mm of collected PPN at 09/09Z;

11th: melted hoar-frost measured at 1800Z;

12th: sporadic rain early hours to ~0730Z;

13th: light drizzle early hours to around dawn;

14th: pr(slight)~1250Z, then ir(slight)/r until ~1345Z;

18th: ir(mainly light) from 1755Z to ~ 2030Z;

20th: melted hoar frost measured at 09Z after spread of Sc; id(very slight) ~midday & late afternoon, with ir(slight) 18-20Z;

25th: ir(slight) from ~08Z until ~ 1030Z;

26th: r(slight), ocnl r, then id(slight) from ~10Z to early afternoon;

27th: ps(mainly slight) from mid-morning to mid-evening;

28th: ps(slight)and/or phs(snow/snow grains) at some time during day;

29th: s(slight)/h(ice pellets) 19Z-2025Z;

30th: r(R), (with short periods rs(slight) early in period) from ~0530Z to ~1730: periods of moderate dr late morning/early afternoon;

30th/31st: pr(slight, ocnl moderate) overnight & up to ~0815Z;

31st: pr(slight) during day, mainly in morning;

31st/1st Jan: pr (slight or moderate) overnight;

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OTHER TOTALS

Number of days thunder heard: (dates).. 01 (02)

Number of days hail < 0.5cm diameter:.. 00

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

Number of days snow/rain & snow:....... 04

Number of days snow lying at 09UTC:.... 00 (AMENDED)

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

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

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Additional comments on the weather in December, 2005

9th: fog (wet) overnight, with period dense/wet fog early hours;

11th/12th: main effect from Hemel Hempstead explosion was the extensive smoke plume that affected the area during the 11th.

27th/28th: away in Poole – snow data estimated.

[thunder]

2nd: tl(slight), with accompanying moderate rain, 1045Z: single clap of thunder only;

[snow]

27th: ps(mainly slight) from mid-morning to mid-evening

28th: ps(slight)and/or phs(snow/snow grains) at some time during day

29th: s(slight)/h(ice pellets) 19Z-2025Z

30th: short periods rs(slight) in heavier PPN 0530-0900Z

... 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 07.2 08.4 06.0 00.4 08.4 09.2 04.6 27.0 A

02 06.7 08.6 05.8 22.4 06.9 09.4 02.9 07.7

03 05.9 08.3 04.2 04.8 07.3 09.1 00.2 00.5

04 03.7 07.3 01.2 00.3 03.7 08.3 - - B

05 04.7 05.9 02.5 - 04.9 08.0 tr tr

06 01.1 06.4 -00.5 - 02.4 05.9 00.2 00.2

07 -00.3 05.4 -02.4 - 00.1 05.4 00.1 07.6 CDE

08 05.4 06.7 04.9 07.5 03.4 07.1 tr 00.1 F

09 00.1 03.4 -01.6 00.1 00.6 04.4 - - G

10 -00.2 03.2 -01.9 - 00.8 06.4 - -

11 -00.9 03.1 -02.9 - -00.9 04.4 00.1 00.2 HI

12 00.5 06.5 -01.5 00.1 05.5 07.5 - tr J

13 03.8 05.5 02.1 tr 04.6 06.0 - -

14 02.9 06.0 00.9 - 06.0 08.5 00.1 00.1 K

15 05.8 08.1 04.6 - 07.8 10.0 - - L

16 07.0 09.8 05.5 - 06.5 11.6 - -

17 -00.6 06.5 -03.2 - -00.4 03.1 - -

18 -04.7 00.6 -06.0 - -03.9 03.1 - 00.3 MN

19 02.5 07.8 -00.5 00.3 02.5 07.3 - 00.1 O

20 -01.0 02.6 -04.0 00.1 01.7 06.9 tr tr PQ

21 05.7 07.2 04.5 tr 07.2 08.9 - - R

22 04.4 08.5 02.3 - 04.5 09.2 - -

23 07.7 08.2 07.2 - 08.1 09.2 - -

24 04.2 08.4 00.6 - 06.2 09.1 - tr

25 02.1 06.8 -00.5 tr 01.0 05.7 tr tr

26 -00.6 02.7 -03.5 - xx.x 05.0 (01.2) (01.2) S

27(-01.0) xx.x(-04.0) - xx.x (02.0)(00.1) (00.1) S AMENDED

28 -02.5 xx.x -04.4 (tr) xx.x (01.0)(tr) (tr) S

29 -01.4 -00.2 -01.6 - -01.5 -00.7 - 04.3 T

30 -01.5 02.3 -02.2 04.3 01.7 09.5 09.9 10.8 UV

31 05.5 09.3 04.1 00.9 04.8 07.9 tr 01.0 W

Remarks:

A. night max.(8.4), also 24hr max for 30th Nov, occurred 01/09Z

B. day min.(3.7), also 24hr min for 5th, occurred 04/09Z

C. day max.(5.4) occurred 07/18Z

D. rainfall (0.1mm) a combination of overnight hoar frost melt & afternoon slight rain

E. day min.(0.1), also 24hr min for 8th, occurred 07/09Z

F. night max.(6.7), also 24hr max for 7th, occurred during night

G. rain recorded 09/09Z from heavy dewfall/wet fog overnight

H. rain recorded 11/18Z from melted hoar-frost

I. day min.(-0.9), also 24hr min for 12th, occurred 11/09Z

J. night max.(6.5), also 24hr max for 11th, occurred 12/09Z

K. night max.(6.0), also 24hr max for 13th, occurred 14/09Z BUT also occurred in it's 'appointed time-slot' during the afternoon 13th

L. night max.(8.1) occurred 15/09Z

M. day min.(-3.9), also 24hr min 19th, occurred 18/09Z

N. day max.(3.1) occurred 18/18Z

O. night max.(7.8), also 24hr max. for 18th, occurred late evening 18th

P. rain recorded 20/09Z from moderate hoar-frost melt

Q. day min.(1.7), also 24hr min. for 21st, occurred 20/09Z

R. night max.(7.2), also 24hr max. for 20th, occurred 21/09Z

S. many items estimated: may be altered at a later date

T. day min.(-1.5) occurred 09Z (also = 24hr min)

U. night max.(2.3) occurred overnight before heavier PPN into low humidity air to reduce temperature.

V. day min.(1.7), also 24hr min 31st, occurred 30/09Z

W. night max.(9.3) occurred 30/18Z

Number of occasions (24hr periods) THIS YEAR (2005)

maximum temperature >= 21degC (70degF) = 75

minimum temperature >= 16degC (61degF) = 11

ANNUAL SUMMARY (2005)

TEMPERATURE:

Individual monthly (24hr) anomalies . . .

+1.9 0.0 +0.8 +1.1 +0.1 +1.8 +0.5 -0.1 +1.9 +3.4 -0.8 -1.1

= +0.79degC

RAINFALL:

Individual monthly totals . . .

26.6 22.3 48.4 57.9 20.4 29.9 50.3 61.2 47.0 83.8 61.4 61.2

= 570.4mm (81%)

Individual monthly anomalies . . .

40% 51% 93% 111% 35% 54% 112% 113% 67% 112% 93% 87%

[ Looking at the Easthampstead Park record (since 1971), the lack of rainfall here has not been particularly remarkable: probably the driest year since only 1996. Of the 12 months of 2005, 7 have been within 15% of the long-term average. ]