PITSFORD HALL WEATHER STATION NORTHAMPTON, UNITED KINGDOM MONTHLY WEATHER REPORT - APRIL 2002 Headline: Warmer than average and dry for the most part with 50% more sunshine than usual. A very unsettled final week. April opened on a warm note with daytime maxima climbing to 20.7C on the 3rd. Some very respectable sunshine totals were recorded also during the first week with 9 hours or more being noted on a daily basis between the 3rd and 7th. There was a little light rain in some parts of the United Kingdom, but the county began on a dry note, a theme which continued until the 17th. High pressure from the Azores region and Scandinavia merged across the UK from the 6th onwards helping to maintain the dry weather. Winds were fairly brisk at first from a generally north-easterly direction and this helped to peg the temperatures down to more normal figures. Clear skies overnight saw some light ground frosts on the 8th and 9th. The weather continued fairly quiet from the 11th onwards with high pressure giving way to a succession of weak weather fronts. However, any rain which these fronts produced fell before reaching the county and the dry conditions persisted. Winds remained very light with daily means typically around 5mph. Further night-time ground frosts were recorded, but daytime maxima were consistently near normal. The 17th saw the end of the prolonged dry spell that had continued since March 30th, although not for long as from the 20th conditions became settled again with no rain recorded until the 25th. Temperatures also began to climb and with daytime maxima generally around the 20C mark from the 21st to the 24th. Good daily sunshine totals were again recorded, mostly in excess of 9 hours from the 21st to the 24th. The final week in complete contrast with the rest of April was unsettled, wet and windy. Almost 85% of month's total rain fell between the 25th and 30th. Up until the 24th only 7.0mm of rain had been recorded which would have ranked the month alongside some of the driest on record, yet within a matter of a week the monthly average had closed in on near normal. The rainfall was occasionally very heavy (7.6mm in just under 2 hours on the 26th and 9.9mm in a little over 5 hours on the 27th). Moderate, occasionally strong, winds gusted up to 44mph on 26th and up to 42mph on the 29th. With temperatures falling back to near normal levels again, the strong wind made for some chilly days too. Climatological & Agromet Statistics - April 2002 Air Temperatures The Highest Maximum: 22.0C on 23rd The Lowest Maximum: 9.8C on 9th The Highest Minimum: 9.1C on 1st The Lowest Minimum: 0.0C on 14th The Mean Maximum: 14.7C The Mean Minimum: 4.4C The Overall Mean: 9.6C Difference from the Monthly Mean: +0.9C Relative Humidity: Highest Relative Humidity (at 0900): 97.6% on 30th Lowest Relative Humidity (at 0900): 66.8% on 12th Mean Relative Humidity (at 0900): 80.1% Dew Point: The Highest Dew Point (at 0900): 14.2C on 22nd The Lowest Dew Point (at 0900): 1.8C on 12th The Mean Dew Point (at 0900): 6.7C Rainfall: Total: 45.2mm Difference from the Monthly Mean: 86.2% Duration: 29.6hrs Highest 24-hour fall (from 0900): 9.9mm on 27th Rain Days (>/=0.2mm): 8 Wet Days (>/=1.0mm): 8 Lowest pH: 5.60 on 17th Sunshine: Total Duration of Bright Sunshine: 193.8hrs Sunniest day: 10.8hrs on 10th Sunless days: 0 Cloud cover (mean at 0900): 4.4 oktas (55.0%) Pressure (reduced to sea level): The Highest Pressure: 1032.8mb on 21st The Lowest Pressure: 991.3mb on 29th Mean Pressure (recorded at 0900): 1015.9mb Winds: Run of wind (mean over 24 hrs): 132.2 miles Mean daily wind speed: 7.2mph Highest 24-hour Wind Speed: 13.3mph on 6th Run of wind (to date): 3967.2 miles Highest Maximum Gust: 44mph on 26th Highest wind strength (at 0900): 21.9mph on 30th Mean wind strength (at 0900): 9.7mph Winds from the Following Directions: N 5 NE 6, E 0, SE 2, S 7, SW 4, W 0, NW 6, Calm 0 Days with: Thunder: 0 Hail less than 0.5cm: 2: 28th & 29th Hail greater than/equal to 0.5cm: 0 Snow or snow & rain: 0 Snow lying: 0 Fog: 0 Air Frost: 0 Duration of Air Frost: 0.0hrs Ground Frost: 8 Evaporation: Total evaporation (tank): 63.99mm Ground Temperatures: Lowest Grass Minimum: -2.6C on 14th Mean Grass Minimum: 2.4C Lowest Concrete Minimum: -0.6C on 12th Mean Concrete Minimum: 3.4C Lowest Bare Earth Minimum: 0.0C on 14th Mean Bare Earth Minimum: 3.9C Soil/Earth Temperatures: Surface mean: 10.9C 5cm mean: 8.8C 10cm mean: 9.0C 20cm mean: 9.3C 30cm mean: 9.6C 40cm mean: 9.5C 50cm mean: 9.8C 100cm mean: 8.9C Climatological observations made at 0900 UTC. Averages refer to the period 1971-2000.