PITSFORD HALL WEATHER STATION NORTHAMPTON, UNITED KINGDOM MONTHLY WEATHER REPORT - APRIL 2005 Headline: Typical weather for April; changeable with frequent showers and/or longer spells of rain. Becoming very mild in the last few days. April began with high pressure in control. The first couple of days were dry, although mist and fog plagued much of the county in the mornings. As the mist burnt away, there were some decent spells of sunshine which led to some particularly warm days with highs exceeding 18C on both the 2nd and the 3rd. The ridge of high pressure weakened on the 3rd allowing some rain across the county. The period through to the 6th was generally unsettled with weather fronts bringing showers and/or longer spells of rain. A cold front introduced colder air on the 4th with a fairly widespread ground frost on the morning of the 5th. A second cold front on the 7th introduced a fairly persistent north-westerly airflow which brought a brief return of wintry weather on the 8th with snow showers and temperatures dropped down to an air frost on the morning of the 9th (-2.5C) and a fairly sharp ground frost (-7.1C). The 9th saw a change to a much more settled spell of weather as a ridge of high pressure extended across the county. It remained generally dry and temperatures recovered, although the county did not enjoy the warmth experienced elsewhere. Temperatures peaked at 15.4C on the 10th and then remained rather modest. There were some sunny intervals, but mostly there was a lot of cloud around. Low pressure influenced the weather around mid-month. Showers and/or longer spells of rain were recorded throughout the period from the 12th to the 15th, some of these showers turning heavy. Further frontal systems introduced more rain through to the 19th, particularly on the 17th which saw rain for much of the day following a reasonably bright start and overnight frost. The period from the 20th to the 24th was mostly dry across the county as pressure recovered. Winds remained light and there were some good spells of sunshine (11.7hrs on the 21st). Temperatures rose to reach daytime maxima around the mid-teens. Clear days did lead to some sharp overnight temperatures and, although no air frosts were recorded at Pitsford, a ground frost of -3.0C was noted overnight on the 21st-22nd. The weather became increasingly unsettled from the 25th onwards, really until the end of the month, as bands of rain worked northwards. 6.0mm fell in just under 3 hours on the 26th and a sharp hailstorm developed on the 27th. Despite the rain, there were some good sunny days and in the last few days it turned very mild with daytime maxima reaching 21.5C on the 30th. Air Temperatures The Highest Maximum: 21.5C on 30th The Lowest Maximum: 6.4C on 8th The Highest Minimum: 12.1C on 30th The Lowest Minimum: -2.5C on 9th The Mean Maximum: 14.3C The Mean Minimum: 4.8C The Overall Mean: 9.6C Difference from the Monthly Mean: +0.5C Relative Humidity: Highest Relative Humidity (at obs): 96.2% on 4th Lowest Relative Humidity (at obs): 67.4% on 22nd Mean Relative Humidity (at obs): 81.2% Dew Point: The Highest Dew Point (at obs): 14.0C on 30th The Lowest Dew Point (at obs): 2.4C on 8th The Mean Dew Point (at obs): 6.8C Rainfall: Total: 34.4mm Difference from the Monthly Mean: 65.5% Duration: 26.6hrs Highest 24 hour fall (obs to obs): 6.4mm on 30th Rain Days (>/=0.2mm): 17 Wet Days (>/=1.0mm): 8 Sunshine: Total Duration of Bright Sunshine: 129.9hrs Sunniest day: 11.7hrs on 21st Days without sunshine: 2 Cloud cover (mean at obs): 6.4oktas Pressure (reduced to sea level): The Highest Pressure: 1030.5mb on 11th The Lowest Pressure: 992.1mb on 18th Mean Pressure (recorded at obs): 1013.0mb Winds Run of wind (mean over 24 hrs): 124.1miles Mean daily wind speed: 6.7mph Highest mean daily wind speed: 14.1mph on 6th Run of wind: 3723.9miles Highest Maximum Gust: 40mph on 5th Highest wind strength (at obs): 30.0mph on 6th Mean wind strength (at obs): 9.0mph Winds from the Following Directions: N 2 NE 3 E 2 SE 4 S 8 SW 3 W 2 NW 6 Calm 0 Ground Temperatures: Lowest Grass Minimum: -7.1C on 9th Mean Grass Minimum: 1.2C Lowest Concrete Minimum: -3.2C on 9th Mean Concrete Minimum: 4.0C Lowest Bare Earth Minimum: -1.2C on 9th Mean Bare Earth Minimum: 4.9C Soil/Earth Temperatures: Surface mean: 9.6 C 5cm mean: 8.8 C 10cm mean: 8.9 C 20cm mean: 9.3 C 30cm mean: 9.6 C 40cm mean: 9.5 C 50cm mean: 9.8 C 100cm mean: 8.6 C Days with: Thunder: 1 Hail less than 0.5mm: 1 Hail greater than/equal to 0.5mm: 0 Snow or snow & rain: 1 Fog 2 Air Frost: 2 Duration of Air Frost: 14.0hrs Ground Frost: 9 Gales: 0 Total Evaporation (tank) 53.93 mm