************************************************************************************** MONTHLY WEATHER REPORT SEPTEMBER 1999 TEXT-ONLY VERSION Hard copy versions of this report, including graphics, can be obtained from the weather station at the following address: Pitsford Hall weather station Pitsford Hall Moulton Lane Pitsford Northampton NN6 9AX Enclosing a stamped address A4 envelope. The full register can be downloaded separately to this report from this web site. If you encounter any problems in downloading data or viewing the files, please contact the station via the answerphone on 07967 438314. For official purposes, data entries should always be double checked with the station office. ************************************************************************************** Pitsford Hall Weather Station Office: Pitsford Hall Northamptonshire Grammar School Pitsford Northampton NN6 9AX Tel. 01604 880306 Fax. 01604 882212 E-mail weather@brixworth.demon.co.uk Web site http://www.brixworth.demon.co.uk/weather Registered member of the Climatological Observers Link Corporate Member of the Royal Meteorological Society Station grading: A Climatological Station No: 91012 Station Manager: M J Lewis, BSc(Hons), FRGS Observers: Christopher Cockrell Simon Fleming Benjamin Goodyear Alexander Jackman Andrew Sunderland Honorary Foundation Observers: Paul Dickens William Keggin Martin Sheehy Andrew Stanton Technician: Mrs S West Groundsman: Mr R Green Brief Climatological Summary September began very warm with temperatures consistently above 23C until the 11th. The month also began very dry, with no appreciable rainfall recorded until well into the second week. From the third week, the weather turned very unsettled. Temperatures saw a progressive decline, only briefly recovering around the 23rd. Heavy showers were frequent, with some notable falls of 22.9mm on the 19th and 11.5mm on the 24th. Across the United Kingdom, this September was the warmest since 1949. At Pitsford Hall, the anomaly was +2.6C. Although rainfall was high, the period of below average rainfall during the first two weeks balanced out the monthly average at 144.9% of the norm. The month was also a bright one, with long hours of sunshine making it the sunniest September since 1991. Statistical Analysis of Air Observations - September 1999 Temperatures: Mean Max: 20.5C Mean Min: 11.8C Mean Temp: 16.2C (mean comparison: +2.6C) Highest Max: 28.1C on 11th Lowest Max: 13.4C on 15th Highest Min: 14.3C on 20th Lowest Min: 8.9C on 17th Relative Humidity: Humidities observed at 0830hrs: Max: 99% on 20th-22nd Min: 68% on 4th Mean: 89.8% Lowest RH (hygrograph record): 28% on 3rd Rainfall: Total for Month: 74.2mm (mean comparison: 144.9%) Max: 22.9mm on 19th Rain Days: 17 Wet Days: 12 Duration: 77.2 hours Rainfall acidity: Lowest pH: 5.8 on 15th,16th & 30th Winds: Max Max Gust: 29mph on 16th Max wind speed at observation: 9mph on 15th,19th Mean wind speed at observation: 3.1mph Max mean 24 hour wind speed: 7mph on 14th Mean mean 24 hour wind speed: 3.2mph Directions: north 3, northeast 0, east 4, southeast 8, south 7, southwest 3, west 0, northwest 1, calm 4, variable 0 Pressures: Max: 1028mb on 10th Min: 985mb on 20th Mean: 1008.3mb Sunshine: Total: 161.9 hours Most in a day: 11.7 hours on 5th No of sunless days: 3 Cloud Cover: Mean cloud cover at observation: 63.8% (5.1 oktas) Ground Observations: Lowest Grass Min: 5.8C on 8th Highest Grass Min: 12.6C on 20th Lowest Concrete Min: 7.4C on 17th Highest Concrete Min: 13.9C on 20th Earth Temperatures: Bare Earth mean: 14.3C max: 24.8C on 4th min: 5.5C on 21st 5cm mean: 14.0C max: 16.6C on 7th min: 10.9C on 17th 10cm mean: 15.0C max: 17.4C on 7th min: 12.5C on 21st 20cm mean: 16.0C max: 18.5C on 6th,7th min: 13.9C on 28th 30cm mean: 16.6C max: 19.1C on 6th min: 14.7C on 17th,28th 40cm mean: 16.9C max: 19.2C on 6th,7th min: 14.3C on 21st 50cm mean: 17.2C max: 19.2C on 6th min: 13.2C on 21st 100cm mean: 16.7C max: 17.8C on 7th min: 12.1C on 21st Other observations: Days with fog recorded at 0830 hours: 5 Mean visibility: 6 (moderate, up to 7km) Days with air frosts: 0 Days with ground frosts: 0 Duration of air frost: 0 hours Days with snow falling: 0 Days with snow lying at observation: 0 Days with hail observed: 0 Days with thunder heard: 2 Days with lightning observed: 1 Gales: 0 Evaporation (tank): 80.23mm Register of Air and Ground Observations - September 1999 1st 2nd 3rd 4th 5th 6th 7th 8th Temperatures Air Max (C) 23.6 26.3 27.2 27.2 26.6 27 23.6 23.1 Air Min (C) 12 13.3 14 12.5 13 14.1 13.9 9.4 Dry Bulb (C) 15.1 16.3 15.8 19.2 15.3 15.6 16.1 13.4 Wet Bulb (C) 14.3 15.4 15 15.8 14.7 14.8 14.9 11.4 RH (%) 91 91 91 68 93 91 87 77 Rainfall Total (mm) _ _ _ _ _ _ tr 1.5 Duration (hrs) _ _ _ _ _ _ 0.2 1.5 Acidity (pH) _ _ _ _ _ _ _ 6.77 Winds (mph) Direction nw calm calm se e calm s s Speed (0830) 2 0 0 5 3 0 3 2 Speed (24 hrs) 2 1 2 3 2 2 3 4 Max Gust 13 12 18 18 12 17 27 26 Pressure (mb) At 0830hrs 1021 1022 1019 1020 1016 1010 1009 1015 From 0600hrs 1 0 0 0 0 0 0 0 Insolation Cloud types cc,ci cc clear ac clear clear st ci Cloud cover 3 3 0 4 0 0 7 5 Sunshine (hrs) 9.9 10.4 9.5 10.7 11.7 9 5.5 3.5 Visibility 5 5 4 7 5 5 5 6 Other Ppt Snow/sleet falling _ _ _ _ _ _ _ _ Depth of snow _ _ _ _ _ _ _ _ Hail (<5mm) _ _ _ _ _ _ _ _ Hail (>/=5mm) _ _ _ _ _ _ _ _ Other Obs Thunder heard _ _ _ _ _ _ _ _ Lightning seen _ _ _ _ _ _ _ _ Ground Obs Grass Min (C) 8.7 10.6 11.1 8.7 10.3 11 11.4 5.8 Concrete Min (C) 10.9 12.1 12.5 10.5 12.1 12.8 13.4 8.4 Bare Earth (C) 17.9 19.4 18.2 24.8 17.1 15.6 16.5 13.1 Soil Temps 5cm 15.1 15.6 15.9 15.8 16 16.1 16.6 13.9 10cm 16 16.6 17 16.8 17 17.3 17.4 15.4 20cm 17 17.5 18 17.9 18.1 18.5 18.5 16.8 30cm 17.9 18.2 18.6 18.7 18.9 19.1 19 18 40cm 18 18.2 18.6 18.9 19 19.2 19.2 18.6 50cm 18.2 18.3 18.6 19 19 19.2 19.1 18.8 100cm 17.4 17.4 17.5 17.6 17.6 17.7 17.8 17.6 Slab 0 0 0 0 0 0 0 0 Ground Without snow 9 9 9 9 9 9 9 9 With snow _ _ _ _ _ _ _ _ 9th 10th 11th 12th 13th 14th 15th 16th Temperatures Air Max (C) 19.6 23.2 28.1 19.9 19 14.3 13.4 18.1 Air Min (C) 9.9 9.6 12.1 13 9.4 11.3 11.8 11.8 Dry Bulb (C) 11.6 12.2 18.6 14 12.1 11.5 11.5 11.5 Wet Bulb (C) 10.9 11.1 17.6 13 11.9 10.3 10.6 10.6 RH (%) 91 87 90 89 97 85 89 89 Rainfall Total (mm) _ _ 0.9 _ _ 4.9 1.3 0.8 Duration (hrs) _ _ 1.5 _ _ 11 7.38 1 Acidity (pH) _ _ 6.47 _ _ 6.4 5.8 5.8 Winds (mph) Direction sw sw s e s n n se Speed (0830) 2 1 3 4 1 3 9 4 Speed (24 hrs) 2 2 4 1 3 7 3 3 Max Gust 18 16 20 14 8 18 18 29 Pressure (mb) At 0830hrs 1023 1027 1017 1015 1013 1015 1015 1015 From 0600hrs 2 0 -2 1 0 0 0 0 Insolation Cloud types ci clear ac cu,ac cs cs ns st Cloud cover 3 0 8 4 7 8 8 7 Sunshine (hrs) 9.5 10.2 5.7 4.6 4.6 0 0 4.5 Visibility 6 7 3 7 7 7 4 6 Other Ppt Snow/sleet falling _ _ _ _ _ _ _ _ Depth of snow _ _ _ _ _ _ _ _ Hail (<5mm) _ _ _ _ _ _ _ _ Hail (>/=5mm) _ _ _ _ _ _ _ _ Other Obs Thunder heard _ _ _ _ _ _ _ _ Lightning seen _ _ _ _ _ _ _ _ Ground Obs Grass Min (C) 6.5 6.1 10.1 11.6 6.1 7.1 10.6 6.4 Concrete Min (C) 9 7.8 11 13.6 8.9 10.1 11.4 8.9 Bare Earth (C) 12 11.4 18.5 15.4 12.6 12.9 13.2 13.1 Soil Temps 5cm 14.2 12.8 16.3 16.4 13.4 13.8 14 12.9 10cm 15.7 14.5 16.8 17.4 14.9 14.9 14.6 13.6 20cm 17 15.9 17.4 18.3 16.1 15.7 15.4 14.4 30cm 17.7 16.7 17.9 18.6 17.1 17.1 15.6 15.4 40cm 18.2 17.3 18 18.6 17.9 17.9 16.4 15.6 50cm 18.9 17.9 18.3 18.7 18.4 18.6 17.2 16.6 100cm 17.5 17.5 17.7 17.6 17.6 17.4 17.1 16.8 Slab 1 0 0 1 0 0 2 1 Ground Without snow 9 9 9 1 9 9 1 1 With snow _ _ _ _ _ _ _ _ 17th 18th 19th 20th 21st 22nd 23rd 24th Temperatures Air Max (C) 20 18.2 16.2 16.2 19.7 19.4 20.4 20.1 Air Min (C) 8.9 10.4 13.3 14.3 10.3 10.9 13 13.5 Dry Bulb (C) 11 14.5 15 14.9 11.2 13.1 13.9 15.1 Wet Bulb (C) 10.3 12.6 14 14.8 11.1 13 13.4 14.6 RH (%) 91 79 89 99 99 99 94 95 Rainfall Total (mm) tr 0.4 22.9 9.5 tr 1.9 2.9 11.5 Duration (hrs) _ 1.63 11.5 4.2 _ 2.6 8.4 2 Acidity (pH) _ _ 6.9 6.13 _ 6.68 6.57 6.53 Winds (mph) Direction e se se se calm e n se Speed (0830) 4 5 9 3 0 1 3 5 Speed (24 hrs) 3 6 5 2 1 4 4 4 Max Gust 21 27 23 16 9 21 21 23 Pressure (mb) At 0830hrs 1006 1004 997 985 994 998 1000 1005 From 0600hrs 0 -0.5 -1 -3 1 1 1 0 Insolation Cloud types cs cu sc cu obs obs cs ci Cloud cover 2 2 7 7 9 9 3 6 Sunshine (hrs) 7.2 2.3 0 2 6.6 1 4.8 4.9 Visibility 6 7 7 6 2 3 7 7 Other Ppt Snow/sleet falling _ _ _ _ _ _ _ _ Depth of snow _ _ _ _ _ _ _ _ Hail (<5mm) _ _ _ _ _ _ _ _ Hail (>/=5mm) _ _ _ _ _ _ _ _ Other Obs Thunder heard _ _ _ _ _ 1 _ 1 Lightning seen _ _ _ _ _ _ _ 1 Ground Obs Grass Min (C) 6.1 7.7 11.2 12.6 6.5 8.1 8.2 12 Concrete Min (C) 7.4 9.3 11.5 13.9 7.5 9.5 9.6 12.4 Bare Earth (C) 10.1 12.6 15 15.1 5.5 7.6 13.6 17.5 Soil Temps 5cm 10.9 11.6 13.6 14.4 13.2 13.2 13.3 14 10cm 12.9 13 14.5 14.9 12.5 14.2 13.9 14.8 20cm 14.1 14.1 15 15.2 16.1 14.9 14.9 15.3 30cm 14.7 15.1 15.5 15.5 15.7 15.6 15.1 15.8 40cm 15.6 15.6 15.7 15.4 14.3 15.8 15.6 15.6 50cm 16.3 16.2 16.2 15.5 13.2 16 16 16.1 100cm 16.6 16.8 16.7 16 12.1 16.4 16.1 15.1 Slab 0 1 1 2 1 0 1 1 Ground Without snow 1 1 1 1 1 1 1 1 With snow _ _ _ _ _ _ _ _ 25th 26th 27th 28th 29th 30th Temperatures Air Max (C) 19.1 17.8 17.1 17.3 17.4 15.8 Air Min (C) 11.7 10.5 11.5 10.4 11.6 11.1 Dry Bulb (C) 14 12.5 12.4 12.1 13.4 12.9 Wet Bulb (C) 13.5 12.2 11.4 10.9 12.6 12 RH (%) 94 96 88 86 91 89 Rainfall Total (mm) 2.1 8.9 0.6 2.1 1.1 0.9 Duration (hrs) 7.5 11 1 2.25 1.25 1.25 Acidity (pH) 6.35 6.28 6.45 6.22 5.95 5.8 Winds (mph) Direction se s sw s se s Speed (0830) 2 4 2 8 2 2 Speed (24 hrs) 2 4 4 4 3 5 Max Gust 13 15 22 26 22 27 Pressure (mb) At 0830hrs 1006 1001 994 999 996 993 From 0600hrs 0 0 0 3 0 2 Insolation Cloud types sc sc as sc cu sc Cloud cover 8 7 5 8 5 8 Sunshine (hrs) 4 4.5 2 3.8 7.2 2.3 Visibility 7 5 7 7 7 6 Other Ppt Snow/sleet falling _ _ _ _ _ _ Depth of snow _ _ _ _ _ _ Hail (<5mm) _ _ _ _ _ _ Hail (>/=5mm) _ _ _ _ _ _ Other Obs Thunder heard _ _ _ _ _ _ Lightning seen _ _ _ _ _ _ Ground Obs Grass Min (C) 10.2 8.5 10.6 8.5 10.6 7.6 Concrete Min (C) 11.1 9.7 11.5 9.4 11.1 9.9 Bare Earth (C) 15 14.1 13.8 12 12.6 12.8 Soil Temps 5cm 13.1 13.1 12.9 11.6 12.5 12.6 10cm 14.1 14.1 14 13.1 13.6 13.5 20cm 14.7 14.8 14.8 13.9 14.1 14.1 30cm 15.5 15.6 15.3 14.7 14.9 14.8 40cm 15.6 15.8 15.6 15.3 15.1 15.1 50cm 16.1 16.2 16.1 15.7 15.6 15.4 100cm 16.3 16.1 16.2 15.8 15.8 15.6 Slab 1 1 1 1 1 1 Ground Without snow 1 1 1 1 2 2 With snow _ _ _ _ _ _ Cloud, Visibility and Ground Observation Codes Standard cloud types Cirrus Ci Cirrocumulus Cc Cirrostratus Cs Altocumulus Ac Altostratus As Nimbostratus Ns Stratocumulus Sc Stratus St Cumulus Cu Cumulonimbus Cb Visibility codes X Dense Fog <20m E Dense Fog up to 20m 0 Thick Fog up to 40m 1 Thick Fog up to 100m 2 Fog up to 200m 3 Moderate Fog up to 400m 4 Very poor visibility up to 1000m 5 Poor visibility up to 2km 6 Moderate visibility up to 7km 7 Good visibility up to 20km 8 Very good visibility up to 30km 9 Excellent visibility 40km Ground Observations Without snow Surface dry (without cracks) 0 Surface moist 1 Surface wet (with puddles) 2 Surface flooded 3 Surface frozen 4 Glaze on ground 5 Surface partly covered in dry dust 6 Surface covered in dry dust 7 Thick covering of dry dust 8 Surface very dry with cracks 9 With snow Ground mostly ice covered 0 Wet/compact snow covering < half 1 Wet/compact snow covering half 2 Ground evenly covered by wet/compact snow 3 Ground unevenly covered by wet/compact snow 4 Dry/loose snow covering < half 5 Dry/loose snow covering half 6 Ground evenly covered by dry/loose snow 7 Ground unevenly covered by dry/loose snow 8 Complete snow cover, drifting 9 Observations of the Concrete Slab Dry 0 Moist 1 Wet 2 Icy 3 Thunder Report 22 September 1999 Started: 15.08 Finished: 15.08 Lightning observed: No Comments: Distant rumbles 24 September 1999 Started: 14.28 Finished: 14.45 Lightning observed: Yes United Kingdom Climatological Analysis - September 1999 High pressure over England, Wales and S Ireland on the 1st resulted in a SW airflow over N districts of the British Isles. Cloud cleared overnight in S districts to give fog by dawn over Cent S England. Over Scotland, cloud and light rain persisted for most of the day; rain fell in Ireland during the morning (despite a surface pressure of 1022 mb here) but by evening this had stopped in all areas. Cloud formed over most parts of England and Wales during the day, but cleared in the evening. (Gravesend 26C, Benson 8C, Lerwick 10mm, Guernsey 11.1h.) Overnight cloud in Scotland and N England helped to make it a warm night, according to minimum temperatures on the 2nd. It was the warmest night on record for any month at Dyce (16.4C) and Leuchars (17.7C). At Ferryhill (Co. Durham) the minimum was 16.5C. Fog formed over much of the S half of England by dawn; thereafter most of England, Wales and S Ireland had a warm day with sunny spells. Parts of Scotland and N Ireland has some light rain during the day, while under anticyclonic conditions it became very warm over the E half of England. Pressure rose to nearly 1024 mb in SE England at 0900 GMT. At Leeds (28C), Edinburgh (26C) and Cardiff (26C) it was the warmest September day on record. (Leeds 28C, Bournemouth 10C, Aultbea 11mm, Penzance 13.0h.) Cloudy skies before dawn on the 3rd led to another mild night over Scotland, Ireland and N England. Minimum temperatures in parts of Northern Ireland were as high as 18C. Fog formed overnight around Irish sea coasts, and in many parts of England and Wales. Some of this fog persisted for much of the day. Ireland and Scotland remained mainly cloudy with some rain in places. England, Wales and S Scotland had another mild day, once fog and early cloud in S Scotland had cleared. (Leeds 28C, Yeovilton 10C, Aultbea 14mm, Scarborough 11.8h.) Clearing skies overnight in NW Scotland moved slowly SE at first on the 4th, with cloud and rain becoming confined to Ireland and parts of SW Scotland by midday. At Kyle of Sutherland (unofficial site) the minimum temperature of 1.8C was in sharp contrast to that of the previous night (15.9C). Prolonged sunshine then resulted in another warm day over much of England and Wales, while cloud and rain spread again to parts of W and N Scotland by the evening. 25.4C at Weston Coyney was the highest in September since records began in 1961. (Southampton 29C, Loch Glascarnoch 3C, Prestwick 4mm, Morecambe 12.6h.) On the 5th cloud and rain was confined to W and N Scotland and to Ireland for most of ther day. Elsewhere, the British Isles were mainly sunny and warm, following the clearance of fog from some Midland counties where the visibility fell below 100m. However, during the evening thunderstorms crossed N into SE and Cent S England (with some heavy rain in Surrey and large hail in the Tadworth area), and fog formed in SE coastal areas. 28.2C at Leeds was the highest ever there in September. Fog plagued some coastal areas of E England for much of the day; at Skegness 17C was the maximum temperature. Temperature reached 28.5C at an unofficial station in urban Bristol. This is the highest recorded September temperature since 1911. (Northolt 29C, Lerwick and Fair Isle 16C max, Topcliffe 7C min, Purley Oaks 30mm, Torquay 12.7h.) Bands of cloud and rain, heavy in places, continued to affect Ireland and Scotland throughout the 6th, pushing slowly SE during the day. 32.3mm fell at Lisburn (Northern Ireland) in 24 hours starting at 1730 GMT. The remainder of the British Isles was again warm and sunny, although cloud and light rain had reached W Wales by late evening. 11mm fell at Wattisham in 1 hour, and sferics were reported off E Kent during early afternoon. (London 28C, Redesdale 7C, Machrihanish 29mm, Isle of Wight 11.1h.) The SE-moving cloud had extended to SE England by dawn on the 7th, but with clearer and cooler conditions then evident in NW Scotland. Rain spread SE from S Scotland during the day, becoming steadily lighter so that much of S England remained dry. To the rear of the cloud band, places as far S as S England then had some sunshine during the day. (Marham 25C, Altnaharra 2C, Isle of Skye 58mm, Penzance 11.2h.) The 8th began with some cloud over S Scotland and Northern Ireland, and rain in W Ireland. By dawn this cloud has spread to large parts of Wales, Scotland and W England, with the rain area extending over much of Ireland and W Scotland with further rain over SW England; this gradual SE movement continued during the day, with only the extreme SE of England remaining sunny although skies did start clearing over Ireland during the late afternoon. The rain fell from an active cold front - at Dun Laoghaire S gale-force gusts were acompanied by a sudden 2mb rise in pressure, with the temperature dropping from a humid 20C to 13C in 3 hours. At Ferryhill the temperature from 19.1C at 2030 GMT to 12.8C at 2230 GMT. At Troon (Ayrshire) there were unconfirmed reports of a tornado, with thunder was heard over parts of N Ireland and SW Scotland. (Gravesend 25C, Aboyne 5C, Tulloch Bridge 29mm, Clacton 10.9h.) The rain continued to move SE during the night, weakening all the while, and by dawn on the 9th was affecting only parts of East Anglia and SE England. Elsewhere, skies cleared and there was some fog in parts of S England. The rain finally cleared the SE by midday, to give most of the British Isles a day of sunny spells. Parts of S England was rather cloudy at times in the afternoon, while there were rain and showers in W Scotland and NW Ireland. (Hove 23C, Pembury Sands 5C, Lusa 35mm, Guernsey 10.7h.) Mainly clear skies overnight resulted in a cool start to the 10th in some N districts. Parts of Scotland and Ireland had a mainly cloudy day (with some rain in the extreme W of both countries), but elsewhere there was much sunshine, although patchy cloud persisted over S England from the S. (Jersey 27C, Lerwick 14C max, Redesdale 1C min, Barra 1.0mm, Prestatyn 12.4h.) Cloud and rain over W Ireland and W Scotland extended to most areas of these countries by dawn on the 11th. Most of England and Wales had a cloudy start; at Cheltenham (unofficial site) the minimum temperature was 17.6C, the highest in a 17-year record for September. Heavy rain over Ireland and Scotland moved slowly SE during the day, weakening in intensity as it moved, to affect the Midland and Cent S England by midnight. Ahead of the day it was a very warm in SE England, but it was much cooler in the clearance behind the rain band. At 1500 GMT temperatures included 28C at Manston (Kent) and 10C at Stornoway. There was some thunder over parts of NE England during the evening. (Gravesend 30C, Stornoway 11C max, Redesdale 8C min, Castlederg 35mm, Folkestone 11.1h.) The rain cleared SE England during late morning on the 12th, which dawn with a touch of ground frost in parts of Scotland under the influence of a weak ridge of high pressure. Further rain and cloud moved across Ireland and Scotland from the SW during the day, while much of England remained generally cloudy. Thunderstorms occurred over W Ireland during the morning. (Herne Bay 24C, West Freugh 2C, Lusa 22mm, Weymouth 10.7h.) The 13th dawned with rain over Scotland and mainly cloudy conditions over England and Wales; clear skies over parts of Ireland led to low temperatures in places there. The rain largely cleared from Scotland during the morning, followed by showers which also fell over W Ireland. Thunderstorms were observed over NW Scotland from the late morning and into the evening. England and wales remained mainly cloudy (with rain in parts of the S and East Anglia) until the evening when skies cleared except in SE England. (Guernsey 23C, Castlederg 4C, Hillsborough 14mm, Penzance 10.1h.) The 14th dawned mainly clear over the British Isles, with ground frost in parts of Scotland and Ireland. At Westruther, the morning minimum temperature was -0.3C. The notable exception to this was the Cent S, SE England and East Anglia where a slow-moving warm over the near continent led to a dull start with light rain. This rain persisted all day in many places and although rainfall amounts were generally small the daytime temperatures were 10-20degC lower than those recorded just 3 days earlier. At Coulsdon (unofficial site) the maximum temperature to 1800 GMT was 12.2C - the lowest maximum in September since 1994. The remainder of the British Isles had a day of sunny spells under the influence of a weak ridge, before cloud and rain pushed into W Ireland before midnight. (Leeds 20C, Kenley 13C max, Aboyne 0C min, Eastbourne 11mm, Tenby 11.5h.) Rain and drizzle continued to affect the SE England, East Anglia and (later) parts of East Anglia overnight; there was was some heavy rain in East Anglia with Wattisham reporting 48mm in the 12 hours ending at 0600 GMT on the 15th (with local roads flooded as a result). Rain continued to move E across Ireland but another clear night over much of Scotland resulted in air frost in places. The rain in the W continued to move slowly E, affecting Wales, SW England and W Scotland by midnight; it turned drier in the SE (while remaining cool and misty in places) as the rain there gradually became confined to East Anglia and E England. (Southsea 21C, High Wycombe 12C max, Aboyne -1C min, Wattisham 49mm, Jersey and Lerwick 11.8h.) Overnight it was mainly cloudy everywhere, with minimum temperatures being quite mild on the 16th; the rain continued to move E, reaching East Anglia by mid-morning, and clearing Wales and SW England by lunchtime. Over Scotland the rain area was slow-moving (although by midnight it was confined to the Northern Isles and the extreme E), and showers developed over Ireland and W districts in a W airstream once the rain cleared. Thunder was reported in parts of SW England during the day. (Poole 21C, Strathallan 7C, Cardinham 40mm, Penzance 8.5h.) A clear night in most areas resulted in ground frost by dawn on the 17th. During the morning cloud spread to Scotland and Ireland, and then to almost all of England and Wales; rain fell overScotland, with rain showers being widespread elsewhere. These showers were accompanied by thunderstorms, especially during the afternoon, over many places in England and Wales, S and Cent. Scotland and E Ireland. Hail was observed at Solihull during a thunderstorm. Later in the afternoon, pressure began to fall steadily over Ireland, with a band of rain reaching W Ireland by midnight. (Gravesend 21C, Altnaharra 1C, Capel Curig 27mm, Bristol 10.8h.) UK Meteorological Office analysis chart for 0000 GMT on the 18th. While it remained clear overnight in parts of E England with some ground frost here by dawn on the 18th, the low to the W of Ireland continued to push its rain E over Ireland and W parts of England, Wales and Scotland by dawn. By late evening the rain had spread to all but the extreme E parts of England; a clearance over Ireland during the afternoon was followed by widespread showers there, and there was thunder over SW England. Falling pressure (the lowest known pressure reported at 3-hourly intervals during the day was 971.6mb at Valentia at 1500 GMT) resulted in gales in exposed W districts, with gusts over 50 kn reported from Malin Head, W Wales (including 54kn at Aberporth at 1500 GMT) and SW England. At Dublin Airport mean winds of up to 30kn with gusts to 45-50kn reported from Dublin airport for much of the morning, and there was extensive but mainly light tree damage. The rain was heavy in places, with 22.8mm at Dun Laoghaire in ther 24 hours starting 0600 GMT. In S Wales there were reports of flooding by the evening, and Irish Sea ferry services were disrupted and cancelled. Rainfall totals reported on the internet included Dorchester 69mm, Haselbury Plucknett 41mm, Weston-super-Mare 45mm, Ebbw vale 89mm, Presteigne 80mm, Stiperstone 66mm and Mold 44mm. (Margate 21C, Redesdale 2C, Lowestoft 9.0h.) UK Meteorological Office analysis chart for 0000 GMT on the 19th. The 19th started mild everywhere, with further heavy rain in SW England and S Wales. The weather over S Ireland was mainly showery, but elsewhere rain fell at sometime during the day, heavy falls over parts of S England being followed by showers. The A470 at Cardiff was closed due to floods, and there was flooding on the A3 and A25 in Surrey. Elsewhere, there were flooded roads in many places in S Wales, the Midlands and W England. Sferics were recorded over SW Ireland later in the evening. (Saunton Sands 21C, Cardinham 11C, Bournemouth 45mm, Torquay 7.6h.) The 20th was a mild and cloudy day everywhere. There were further falls of heavy rain, notably in S England, Northern Ireland, S Scotland and N England, with rain or showers in other districts, as an area of low pressure tracked from Cherbourg to NW Ireland during the day. Dublin reported a pressure of 980.6mb at 1800 GMT, and by early morning there was flooding in North Yorkshire and Sussex. 981mb at Dun Laoghaire was the lowest recorded in September in 11 years. Casement Airport had 45mm rain up to 0000 GMT on 21st and Dun Laoghaire had 32mm up to 0700 GMT on the 21st. Later in the day the Environment Agency issued yellow flood alerts for places in Wales, the Midland and SW England, and the A914 near Cupar was closed by floodwater in the afternoon. There were thunderstorms in parts of NE England during mid-morning, and later along a line from Kent to N England. At Coulsdon (Surrey) 40.6mm fell in 18 hours ending 1500 GMT, with heavy thunderstorms reported. Over the Forest of Dean a funnel cloud was filmed. (Jersey 21C, Pembrey Sands 9C, Kenley 58mm, Guernsey 5.5h.) The low continued to move slowly NW over Ireland on the 21st giving a rather cloudy day in most places. There was widespread rain, heavy in places, over N Ireland and W Scotland, with gusts up to 40kn in places here. Thunderstorms occurred over parts of SE England and East Anglia during the late afternoon and evening. (Hastings 22C, Larkhill l7C, Hastings 33mm, Bournemouth 10.1h.) The 22nd began cloudy in S England, ahead of a frontal system that pushed N across England and Waes during the day. This brought widespread rain and poor visibility, with thunderstorms reported over much of England, Wales and S Scotland, along with some some activity in S Ireland. In Cent. London torrential rain and thunderstorm with flooding brought visibility down to 300 metres at one point. Early patchy cloud over Scotland remained during the day; the best of the sunshine was in W Scotland, ahead of the cloud which affected S scotland later in the day. (Jersey 22C, Aviemore 8C, Hayling Island 29mm, Stornoway 10.8h.) A S airflow on the 23rd brought bands of rain and showers to many parts of the British Isles. Thunderstorms were reported over W Ireland, Cent. S England and NE Scotland. (Coltishall 21C, Aviemore 6C, Lossiemouth 23mm, Tiree 8.1h.) Further bands of rain and thunderstorms affected much of England and Wales on the 24th, while an area of low pressure remained centred near NW Scotland. SW Scotland and Ireland remained dry in places, although at Dun Laoghaire 7mm of rain fell in 20 minutesaround 1400 GMT. (Guernsey 22C, Altnaharra 7C, Pembrey Sands 40mm, Guernsey 7.6h.) Winds decreased a little on the 25th, and there were some early morning fog pathes in S Ireland, Wales and SW England. Showers were again widespread, and thundery over SW England, SE Ireland and much of the Midlands and East Anglia as a shallow area of low pressure crossed from S Ireland to The Wash. A small tornado was reported on the Suffolk/Essex border. (Gravesend 21C, Hillsborough 6C, Coltishall 29mm, Falmouth 9.8h.) The 26th was a generally cloudy day over the British Isles, although over Scotland a lack of cloud in places led to some ground frost. During the afternoon a slow-moving front brought rain to SW Ireland around lunchtime, and later to Wales, SW and Cent. S England. Thunderstorms were reported in parts of SE and E England during the afternoon, and around the coast of SE England during late morning. A waterspout was observed about 8 to 12 km offshore from Hastings from 1020 to 1025 GMT, beneath a very dark cumulonimbus cloud. (Poole 21C, Altnaharra 3C, Llanbedr 22mm, Bournemouth 8.7h.) Another cloudy day on the 27th resulted from a slow-moving frontal system. This brought rain and showers to most parts of S Ireland, Wales and England during the day, with some heavy rain and thundery activity over SE England during late afternoon and evening. At Dun Laoghaire the stalled front gave 13mm in 1 hour, and the rainfall total for September so far, 135mm, now exceeds the previous highest there in 1976. (Herne Bay 20C, Biggar 4C, Folkestone 31mm, Stornoway 6.8h.) A clearance in the W after the rain brought a ground frost to places in Cent. Ireland and Cent. Scotland by dawn on the 28th. There were also fog patches in parts of SW Scotland and N Ireland, although by dawn another area of rain had reached SW Ireland, pushing across most of Ireland, Wales and S scotland by midnight. There were a few showers over N and Cent. Scotland. (Guernsey 20C, Tulloch Bridge 2C, Eastbourne 12mm, Folkestone 8.1h.) Low pressure on the 29th brought a mild SW airflow over S districts. In Ireland temperatures rose to 19C at Dublin and Belmullet. There were further spells of heavy rain and showers, with thunderstorms over N Wales and parts of N England, and over S districts of England, in both cases moving generally E. (Herne Bay 20C, Loch Glascarnoch 4C, Capel Curig 45mm, Cromer 8.1h.) E-moving fronts and troughs, associated with low pressure over N areas on the 30th brought further rain and showers. It was cloudy in most places, and the best of the warmth was in S England. (Poole 20C, Shap and Wick 4C, Jersey 14mm, Cardiff 6.6h.) Information contained in the Climatological Summary supplied courtesy of Roger Brugge, Climatological Observers Link. Notable Weather Events in Northamptonshire The following report is taken from the weather station's web site 19 September 22.9mm rainfall recorded at Pitsford Hall, rainfall lasting for 11.5 hours. Highest daily total since 25 August. Rainfall continuing at morning observation (8.30BST) giving a total of 9.5mm on 20 September. 22-26 September 5 consecutive wet days (daily rainfall in excess of 1mm). Highest totals recorded on 24 September (11.5mm) and 26 September (8.9mm). On 24th September, 6.6mm of rain fell between 19.20 and 20.05BST. On 26th September, 8.3mm of rain fell between 23.00 and 3.25BST, of which 6.7mm fell in two hours between 1.00 and 3.00BST, and 3.4mm fell between 2.20 and 2.55BST. Reports from Northants Weather Watchers Reports received from Pitsford Hall weather station's network of weather enthusiasts across Northamptonshire. The weather station is not responsible for any inaccuracy contained in these reports. They are supplied for interest only. From Jeremy Borrett : WILBY'S TOTAL MONTHLY & YEARLY RAINFALL (BETWEEN 1994 AND 1999) =============================================================== ______________________________________________________________________ 1994 (mm) 1995 (mm) 1996 (mm) 1997 (mm) 1998 (mm) 1999 (mm) ______________________________________________________________________ January 80 83 44 22 88 109 February 44 76 56.5 66.5 8 21 March 46 55 36.5 11.5 82 37.5 April 54 31 51.5 19 175 76 May 62 36 24.5 92.5 16 68 June 24 95 34.5 149 126 77.5 July 24 19 69 49 19 31.5 August 36 9 70.5 66 62 87 September 122 121 11 42 60 65.5 October 76 28 45.5 81.5 130 November 52 82 79 84 45 December 62 96 55 78 56 ______________________________________________________________________ TOTAL (mm) 682 731 577.5 761 867 507.5 ______________________________________________________________________ WILBY'S AVERAGE DAILY TEMPERATURE (1995 TO 1999) ___________________________________________________________ 1995 (°C) 1996 (°C) 1997 (°C) 1998 (°C) 1999 (°C) ___________________________________________________________ January 4 3 1 5 6 February 6 5 7 9 6 March 7 4 3 7 8 April 12 12 14 10 15 May 16 12 16 19 19 June 19 19 20 17 19 July 25 21 24 20 21 August 26 21 27 25 19 September 19 18 21 19 19 October 14 13 13 11 November 6 4 9 5 December 1 2 5 6 ___________________________________________________________ WILBY'S AVERAGE AIR PRESSURE (1995 TO 1999) ___________________________________________________________ 1995 (mb) 1996 (mb) 1997 (mb) 1998 (mb) 1999 (mb) ___________________________________________________________ January 1008 1010 1024 1011 1014 February 1005 1018 1014 1022 1017 March 1009 1012 1024 1020 1008 April 1016 1016 1023 1001 1011 May 1015 1014 1015 1017 1017 June 1012 1020 1010 1013 1017 July 1013 1017 1021 1013 1019 August 1017 1024 1017 1019 1014 September 1013 1017 1023 1012 1009 October 1016 1014 1017 1011 November 1014 1010 1001 1016 December 1016 1015 1009 1009 ___________________________________________________________ WILBY'S AVERAGE DAILY WIND SPEED (1995 TO 1999) ________________________________________________________________ 1995 (mph) 1996 (mph) 1997 (mph) 1998 (mph) 1999 (mph) ________________________________________________________________ January 9 4 1 8 1 February 5 3 7 5 5 March 7 4 3 7 3 April 3 3 4 7 7 May 5 4 7 2 5 June 2 2 13 4 2 July 3 3 7 7 5 August 3 3 9 8 3 September 3 3 6 4 4 October 3 2 6 8 November 2 1 4 1 December 2 1 6 7 WILBY'S SEPTEMBER 1999 MONTHLY WEATHER REPORT ============================================= Wind direction -------------- North: 0 days South: 6 dayS East: 1 day West: 4 days North-west: 2 days North-east: 0 days South-west: 4 days South-east: 5 day Variable: 4 days Calm winds: 3 days Total: 29 days Wind speed ---------- Average wind speed (mph): 4mph Highest wind speed (mph): 24mph (18th) Lowest wind speed (mph): 0mph (2nd,5th,6th) Temperature ----------- Average temperature: 19.1°C Highest temperature: 26.2°C (11th) Lowest temperature: 9.9°C (8th) Rainfall -------- Total rainfall (mm): 65½mm Highest rainfall (mm): 20½mm (20th) Air pressure ------------ Average air pressure: 1009mb Highest air pressure: 1027mb (9th) Lowest air pressure: 990mb (20th) From Steve Jackson: 2 September We had the hottest September day since 1991 in Coventry today 92nd) with a maximum of 26.2C - in 1991 the air maximum reached 27.8C - perhaps we will reach this tomorrow:-) Appendix Weather Station Inventory (including equipment in active use as of 1 October 1999) Rooftop Enclosure and Office Standard Stevenson screen containing Mahogany mounted maximum and minimum thermometers (Casella type) Wet and dry bulb hygrometer Large pattern Stevenson screen containing Sheathed pattern maximum and minimum thermometers (UK Met Office with calibration certificates) Sheathed pattern wet and dry bulb thermometers (UK Met Office with calibration certificates) Thermograph (UK Met Office) Hair Hygrograph (UK Met Office) Campbell-Stokes Sunshine Recorder (UK Met Office MKII) Snowdon-type pattern raingauge (UK Met Office) British Association pattern raingauge (for recording rainfall acidity) Tilting syphon rainfall recorder (UK Met Office MKI) Wind vane (UK Met Office) Totalising Cup-Counter Anemometer (UK Met Office, mounted on 5m mast) Digital wind direction system (Digitar, for determination of maximum gust) Fortin-pattern mercury barometer Open-scale micro-barograph (UK Met Office) High resolution digital pH meter (Hanna) Two PC's with modem links and dedicated fax/phone line Ground Enclosure Soil thermometers (5cm, 10cm, 20cm, 30cm, 40cm, 50cm, 100cm) (Negretti and Zambra) Grass and concrete minimum thermometers (UK Met Office with calibration certificates) Hook Evaporimeter (Negretti and Zambra, used periodically) Bare Earth thermometer (Negretti and Zambra) Bare Earth Plot and Concrete Slab