Summary for May 2005

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HEADLINE: VERY DRY OVERALL. LENGTHY COOL SPELLS - WARMER LAST WEEK

(last updated: 01/1100 JUNE)

[ NB: no data 03/0900 to 07/1800 .. estimates made from adjacent stations at this date. ]

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):... 30.2(27)

Highest 24hr maximum (date):.. 30.2(27)

Lowest night minimum (date):... 00.8(11)

Lowest 24hr minimum (date):... 00.8(11)

Lowest overnight grass minimum (date):... -01.8(11)

[ number of days grass minimum < 0degC: ... 03 ]

[ Lowest day maximum (date):... 11.6(04)]

[ Highest night minimum (date):... 14.8(26)]

A. Mean Day (09-18Z) maximum: ... 17.3

A. Mean Night (18-09Z) minimum: ... 07.8

A. Mean of Day Max & Night min: ... 12.5

B. Mean 24hr maximum:... 17.3

B. Mean 24hr minimum:... 07.8

B. Mean of 24hr max & min:... 12.5 [+0.1 anomaly on eLTA of 12.4degC]

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

Nr of days minimum at 09UTC <0.0degC:00

Nr of days maximum at 09UTC >=21degC:04

Nr of days maximum at 09UTC >=25degC:01

Nr of days maximum at 09UTC >=30degC:01[dates: 27]

(Notes relating to temperature & allied observations:

Due to absence, the lowest day maximum of 11.6 on the 4th is an estimated value.

Although the mean temperature for the month is around 'average', this disguises some notably cool daytime periods: 16 of the days had maxima => 0.5degC below the LTA, and on five days (4th, 9th-11th & 17th), the best temperature was 3 or more degC below the eLTA.

As late as the 17th of the month, the day maximum reached just 13.2°C, 4degC below average: only the late-month 'correction', afforded by the warm spell 25th-27th, prevented us ending up with a negative anomaly.)

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PRECIPITATION (PPN/mm)

Total rainfall/melted snow etc:... 20.4 [ 35% of eLTA of 58mm]

Highest 24hr total:............... 8.2(21)

No. days PPN total >= 0.2:10

No. days PPN total >= 1.0:06

No. days PPN total >=10.0:00

No. days PPN total >=25.0:00

(Notes relating to precipitation & allied observations:

1st: ir(slight/medium level instability) ~0720Z [ no measured amount – to April rainfall ]; ir(slight/medium level instability 09-10Z;

2nd: overnight slight rain, mainly 04-05Z;

3rd: r(slight) early hours; r(slight)/r from ~ 0845Z through to early/mid- afternoon;

[ ** entries from midday 3rd to midday 7th based on information from Dave Lloyd (Bracknell) and Phil Rowley (Winkfield).**]

3rd/4th: rain/drizzle overnight, mainly slight – and through much of afternoon 4th;

6th: pr(slight), mainly afternoon;

7th: pr(slight, isol moderate) ~12Z to 18Z;

8th: pr(slight) through afternoon;

9th: pr(slight) from late morning, with pr 1600-1615Z;

10th: very light pr afternoon;

16th: ir(slight) from ~13Z, continuous from 16Z, ocnl r 17-18Z, dying out early evening;

18th/19th: ir(slight) overnight;

19th: r/d(slight) from ~0515Z, continuing off and on through day, always light, dying out by 17Z;

19th/20th: r(slight)/r overnight;

20th: r(slight)/r from ~07Z, dying out soon after 09Z;

21st: r(slight) began 0730Z, became r(0830Z), then r(R) until ~10Z; pr(slight), ocnl pr rest of day until ~1630Z;

22nd: ir(slight) early hours; pr(very slight) early/mid afternoon;

22nd/23rd: light rain 04-05Z (see comments below);

24th: dr(slight/moderate) early hours onwards – becoming intermittent from ~ 1030Z & ceased by ~11Z;

25th: ir(few spots) ~0915Z;

26th: ir(light) 0915-0930Z;

(01 June: ir(slight) 08-0830Z)

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OTHER TOTALS

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

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

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

Number of days snow/rain & snow:....... 00

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

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

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

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Additional comments on the weather in May, 2005

1st: spectacular electrical storms visible from here to the north or northwest between 0100 and 0145Z: a 'rolling barrage' of thunder, no breaks at all for at least half an hour, with "Hollywood-style" lightning visible: mainly CC and intra-cloud; did not observe any CG strikes from here. At peak of event (0115-0130Z) lightning coming at a rate of 30-40 discharges per minute; no rain from this event;

2nd: possible dust/fine-sand from light rain overnight, though also possible it is from pollen;

23rd: light rain (medium level) 04-05Z, *may* have deposited dust: certainly many cars across a wide area seem to be so affected.

30th: 08-11Z, on the western edge of some 'severe' weather with Cu con and / or Cb seen to the E/NE;

In the composite Easthampstead Park / Tawfield record, this May is the driest since May 1991 & one of the 'top-5' driest such-named months in the series which started in 1971.

... 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 14.2 20.5 11.9 tr 18.2 23.5 tr 00.1 -

02 12.2 20.5 11.5 00.1 14.6 20.6 - tr

03 10.6 18.2 08.4 tr **.* (17.8)(tr ) (00.2)

04 (09.7) **.* **.* (00.2) **.* (11.6)(tr ) (tr )

05 03.1 **.* 01.1 (- ) **.* 18.3 (- ) (- )

06 (10.2) **.* **.* (- ) **.* (17.2)(tr ) (00.9)

07 (08.6) **.* **.* (00.9) **.* 14.7 00.7 00.7

08 04.0 11.6 02.0 - 10.9 14.6 00.1 00.1

09 02.3 11.6 00.0 - 08.6 12.8 01.4 01.4

10 02.2 10.8 -00.3 - 09.4 12.4 tr tr

11 00.8 11.4 -01.8 - 08.7 13.5 - -

12 03.0 12.0 01.8 - 11.2 14.5 - -

13 07.1 12.8 05.9 - 11.0 16.7 - -

14 06.3 13.3 06.0 - 09.2 15.5 - -

15 01.6 13.0 -00.7 - 10.9 18.3 - -

16 07.3 16.5 05.7 - 09.0 17.0 01.1 01.2 A

17 04.6 09.0 03.4 00.1 08.5 13.2 - -

18 04.5 13.1 02.9 - 12.4 15.1 - 00.5 B

19 09.0 12.4 08.2 00.5 11.7 14.5 00.5 04.2 C

20 12.4 14.4 11.7 03.7 13.1 17.5 tr 01.5

21 07.7 15.2 04.7 01.5 11.6 15.4 08.1 08.2

22 08.6 13.5 07.5 00.1 12.7 16.3 tr tr

23 06.3 14.1 04.4 tr 13.6 16.7 - 01.4

24 09.7 13.7 08.7 01.4 12.0 18.1 tr tr

25 10.4 16.0 09.5 - 14.6 22.1 tr tr D

26 14.8 19.5 14.0 - 20.1 23.7 tr tr

27 12.0 22.7 10.0 - 22.7 30.2 tr tr

28 14.1 28.2 13.5 - 16.5 19.8 - -

29 08.1 18.3 05.7 - 13.0 16.7 - -

30 09.1 16.8 08.0 - 16.1 18.6 - - E

31 07.7 17.1 06.0 - 16.6 19.9 - tr

Remarks:

A. day min.(9.0) occurred 16/18Z [air-mass change afternoon]

B. night max.(13.1) occurred 18/09Z

C. day min.(11.7), also 24hr min. 20th, occurred 19/09Z

D. day min.(14.6), also 24hr min. 26th, occurred 25/09Z

E. night max.(16.8), also 24hr max. 29th, occurred 30/09Z

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

maximum temperature >= 21degC (70degF) = 05

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

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Spring summary:

meanTn(anom) meanTx(anom) mean24h(anom) totRain(anom)

Mar: 04.1 (+0.7) 11.0 (+1.1) 07.5 (+0.8) 48.4 (93%)

Apr: 05.7 (+1.0) 14.2 (+1.3) 09.9 (+1.1) 57.9 (111%)

May: 07.8 (+0.3) 17.3 ( 0.0) 12.5 (+0.1) 20.4 (35%)

Season: (+0.7) (+0.8) (+0.7) 126.7 (78%)

(the seasonal mean anomaly of +0.7 is the same as last year; however, the pattern was different, with a cold March followed by warm April & May: the inverse pattern to this year)

Rainfall anomaly this year (so far) = 66%

Running 12 month temperature anomaly: +0.8 degC

Running 12 month rainfall anomaly: 77% (down from 82% last month)