PITSFORD HALL WEATHER STATION NORTHAMPTON, UNITED KINGDOM MONTHLY WEATHER REPORT - MAY 2005 Headline: A warm start but with the exception of a very warm day on the 27th cooler than average. Two distinctly cyclonic periods delivering a fair amount of rain, although below average. May opened with a fairly complex area of low pressure dominating the scene. Initially placed to the west of Ireland this low tracked eastwards across the UK delivering a fair amount of rain across the county on the 3rd. The rain saw temperatures fall quite sharply from a high of 22.3C on the 1st. In fact temperatures throughout much of the month were to remain fairly modest, not recovering above 20C until the 25th. From the 5th onwards there were some chilly nights behind a cold front which had cleared the county the previous evening. With a brisk breeze mainly from the north or north-west, it didn't feel particularly warm either by day and again there were some stiff showers, particularly on the 7th which saw 5.0mm falling in a little under an hour at Pitsford. By the 9th temperatures had fallen sufficiently to give rise to a ground frost. In fact, ground frosts were recorded at Pitsford on the next three nights as well. Clear skies under accompanying anticyclonic conditions were the primary cause of the particularly chilly period from the 10th to the 15th. The wind also swung round to a chilly easterly direction and picked up on the 13th as pressure began to fall. The fall in pressure brought with it a cold front on the 16th which gave rise to dull and damp day across the county. Although a ridge of high pressure intervened on the 18th the weather remained cyclonic until the 23rd. Rain approached the county from the south-west on the 19th and the next few days remained generally unsettled with heavy showers and/or longer spells of rain. Some thunderstorms worked through the county during the 21st and 22nd delivering a fair amount of rain (5.2mm in just over an hour on the 22nd). Temperatures from the 24th finally recovered. Although some weak frontal systems worked across the county they delivered very little rain and the south-westerly airstream saw temperatures finally exceed 20C on the 25th reaching a high of 28.3C on the 27th, the warmest day in May in Northampton since 1997 (29.8C). However, the warmth was short-lived as a weakening cold front worked in from the west overnight. The month thus ended on a dry night with temperatures approaching the average for late May. Climatological & Agromet Statistics Air Temperatures The Highest Maximum: 28.3C on 27th The Lowest Maximum: 11.7C on 9th The Highest Minimum: 13.0C on 26th The Lowest Minimum: 0.5C on 12th The Mean Maximum: 16.5C The Mean Minimum: 6.4C The Overall Mean: 11.5C Difference from the Monthly Mean: -1.0C Relative Humidity: Highest Relative Humidity (at obs): 94.4% on 3rd Lowest Relative Humidity (at obs): 54.6% on 18th Mean Relative Humidity (at obs): 76.5% Dew Point: The Highest Dew Point (at obs): 17.1C on 27th The Lowest Dew Point (at obs): 3.4C on 17th The Mean Dew Point (at obs): 8.4C Rainfall: Total: 43.6mm Difference from the Monthly Mean: 87.6% Duration: 27.9hrs Highest 24 hour fall (obs to obs): 9.2mm on 21st Rain Days (>/=0.2mm): 12 Wet Days (>/=1.0mm): 11 Sunshine: Total Duration of Bright Sunshine: 200.5hrs Sunniest day: 11.5hrs on 14th & 15th Days without sunshine: 1 Cloud cover (mean at obs): 6.3oktas (78.8%) Pressure (reduced to sea level): The Highest Pressure: 1027.7 mb on 11th The Lowest Pressure: 1004.8 mb on 22nd Mean Pressure (recorded at obs): 1016.3 mb Winds Run of wind (mean over 24 hrs): 125.9miles Mean daily wind speed: 6.8mph Highest mean daily wind speed: 12.3mph on 13th Run of wind: 3902.2miles Highest Maximum Gust: 42mph on 7th Highest wind strength (at obs): 19.6mph on 7th Mean wind strength (at obs): 8.9mph Winds from the Following Directions: N 5 NE 2 E 2 SE 0 S 10 SW 3 W 1 NW 8 Calm 0 Ground Temperatures: Lowest Grass Minimum: -2.8C on 11th Mean Grass Minimum: 3.4C Lowest Concrete Minimum: 0.7C on 11th Mean Concrete Minimum: 6.0C Lowest Bare Earth Minimum: 1.7C on 17th Mean Bare Earth Minimum: 6.6C Soil/Earth Temperatures: Surface mean: 13.5C 5cm mean: 12.0C 10cm mean: 12.1C 20cm mean: 12.4C 30cm mean: 12.7C 40cm mean: 12.4C 50cm mean: 12.8C 100cm mean: 11.5C Days with: Thunder: 2 Hail less than 0.5mm: 2 Hail greater than/equal to 0.5mm: 0 Snow or snow & rain: 0 Fog 0 Air Frost: 0 Ground Frost: 6 Gales: 0 Total Evaporation (tank) 80.77mm All data (C) Pitsford Hall weather station. Pitsford Hall weather station is a non-profit making organisation run by Northamptonshire Grammar School to provide quality weather data for the local community. Official Patron: Alex Deakin Honorary Patron: Michael Fish All data (C) Pitsford Hall Weather Station, Pitsford Hall, Pitsford, Northants NN6 9AX Tel. 01604 880306 Extension 314 Fax. 01604 882212 Recorded Forecast 07967 438314