PITSFORD HALL WEATHER STATION NORTHAMPTON, UNITED KINGDOM MONTHLY WEATHER REPORT - DECEMBER 2005 Headline: Generally mild and unsettled at first. A brief cold snap mid-month heralded snow showers in the days after Christmas. The month opened with low pressure dominating the weather across a large part of the UK. Across the county it was generally mild with temperatures close to normal for the time of year and bands of frontal rain swept eastwards bringing 8.7mm on the 1st and 7.8mm on the 2nd (in the 24 hour period measured from 0900hrs). Winds were generally from the south and fresh at times, gusting to around 30mph on the 1st and 2nd. Apart from the 4th, it was quite dull with little extended sunshine. The low began to fill on the 5th and by the 7th a weak ridge of high pressure developed. However, this ridge didn’t stop a band of rain working in from the west delivering 3.6mm in just over 4 hours. Nevertheless, this ridge did introduce some very light winds indeed calm conditions by 0900hrs on the 9th resulting in fairly extensive fog. Visibility at Pitsford was reduced to 200m. Temperatures by day remained generally mild for the time of year, although they fell below or close to freezing overnight. As high pressure developed further over the next few days some good spells of sunshine were recorded. High pressure established to the south from the 11th introduced a generally west or north-westerly wind across the county. There was some fog around on the 11th, but unlike many other places it lifted to allow temperatures to climb to around 8.9C in over 4 hours of bright sunshine. By contrast parts of Oxfordshire only reached 2.5C. A cold front then worked southwards resulting in slightly depressed maxima over the next couple of days before temperatures once again recovered with a westerly flow prevailing to a high of 10.4C on the 15th. Temperatures fell sharply after the 16th as a cold front introduced a colder northerly flow. Many areas outside the county reported showers, even as hail or snow in areas further east, although it remained dry at Pitsford. Temperatures on the 17th climbed to only 3.7C compared to 9.4C the day before. The cold snap was short-lived, however, as a warm front worked in from the west to be felt across the county on the 18th. A small amount of rain accompanied the front. Some warm and sunny conditions followed the front although with high pressure in charge to the south a fairly penetrating frost followed. Temperatures on the morning of the 18th fell to -4.5C (-9.9C over grass) and again to -3.3C on the 19th. From the 21st onwards the weather became rather dull but mild. Daytime temperatures typically reached 9 or 10C and it was equally mild overnight. By Christmas Day high pressure had built up across the UK. Frontal systems caught up in this high introduced some patchy rain and showers for some areas, but it was essentially dry across the county albeit rather dull. As the wind took on a more north-easterly direction on the 27th some snow showers were fed in across the county. 2cm lay on the ground on the 27th and continued flurries through the day added a further 3cm by the 28th. Daytime temperatures consequently on the 28th reached just 0.5C at Pitsford and remained below freezing all day at Desborough on 29th (-2.2C maximum). The month ended as much milder conditions worked in from the west on the 30th. This brought a fair amount of rain, but not the snow on its leading edge as had been forecast. New Year’s Eve saw a high by day of 8.5C with temperatures held above freezing overnight at 3.5C.   Air Temperatures     The Highest Maximum:   10.6C on 5th The Lowest Maximum:   0.5C on 28th The Highest Minimum:   6.9C on 16th The Lowest Minimum:   -4.5C on 18th The Mean Maximum:   7.2C   The Mean Minimum:   1.2C   The Overall Mean:    4.2C   Difference from the Monthly Mean:  -1.3C        Relative Humidity:     Highest Relative Humidity (at obs):  100.0% on 25th & 29th Lowest Relative Humidity (at obs):  66.8% on 7th Mean Relative Humidity (at obs):  92.7%        Dew Point:     The Highest Dew Point (at obs):  7.1C on 16th The Lowest Dew Point (at obs):  -4.6C on 18th The Mean Dew Point (at obs):   2.9C        Rainfall:     Total:     34.6mm   Difference from the Monthly Mean:  55.0%   Duration:     32.3hrs   Highest 24 hour fall (obs to obs):  8.7mm on 1st Rain Days (>/=0.2mm):   13    Wet Days (>/=1.0mm):   7         Sunshine:     Total Duration of Bright Sunshine:  49.3hrs   Sunniest day:    4.1hrs on 11th Days without sunshine:   7 Cloud cover (mean at obs):   5.8oktas (72.5%)       Pressure (reduced to sea level):     The Highest Pressure:   1041.2mb on 13th The Lowest Pressure:   980.5mb on 2nd Mean Pressure (recorded at obs):  1017.9mb        Winds     Run of wind (mean over 24 hrs):  120.2miles   Mean daily wind speed:   6.5mph  Highest mean daily wind speed:  13.7mph on 15th  Run of wind (to date):   3725.3miles   Highest Maximum Gust:   48mph on 16th Highest wind strength (at obs):  26.5mph on 16th Mean wind strength (at obs):   8.1mph        Winds from the Following Directions:       N 4 NE 2 E 0 SE 1 S 5 SW 6 W 3 NW 8 Calm 2         Ground Temperatures:      Lowest Grass Minimum:   -9.9C on 18th Mean Grass Minimum:   -2.9C   Lowest Concrete Minimum:   -5.2C on 18th Mean Concrete Minimum:   0.5C   Lowest Bare Earth Minimum:   -3.5C on 18th Mean Bare Earth Minimum:   0.7C        Soil/Earth Temperatures:      Surface mean:    3.6C   5cm mean:    3.6C   10cm mean:    3.9C   20cm mean:    4.5C   30cm mean:    4.8C   40cm mean:    4.8C   50cm mean:    5.4C   100cm mean:    6.5C             Days with:     Thunder:     0    Hail less than 0.5mm:   0    Hail greater than/equal to 0.5mm:  0    Snow or snow & rain:   2 Snow lying:    4 Fog:     4 Air Frost:     10 Duration of Air Frost:   52.0hrs Ground Frost:    26                Total Evaporation (tank)   10.95mm