Windrush Weather

Author: Eric Gilbert

  • Wind speeds

    I recently decided to analyse my records of wind speeds, the most accurate go back to the year 2000 when my anemometer was moved to a very high position, well above roof height. The initial results gave me concern as recent years have shown a decline in wind speed-readings. I had wondered if the repeated attack on the instrument by a rogue rook, two years ago, had damaged the unit.

    My equipment captures data every five seconds and from these records I find that there has been a downward trend in average annual wind speeds since 2007 – the fall being most notable for the last two / three years.

    2001

    2002

    2003

    2004

    2005

    2006

    2007

    2008

    2009

    2010

    4.3

    4.6

    4.3

    4.3

    4.4

    4.3

    4.1

    3.9

    3.3

    3.1

    Looking specifically at readings in the winter (meteorological) period, December 1st to February 28th, I discovered a reduction in gusts of 20mph +, by an average of four per year. The statistics for gusts of 30mph + produced a reduction of three per year.

  • Monthly Summary January 2011

    In January 2011 we enjoyed mild if overcast days when the maximum was four to five degrees above the average (12th and 16th) or in contrast as on the 29th when the maximum was only 0°C. Some nights were warm with a minimum of 10.4° and 9.5°C (14th and 13th respectively) when the average is 1.3°. A total of 16 nights of air frost was above the average of 11 over the last 27 years with the early morning of the 31st being extremely cold when I recorded a minimum of -8.5°C. The record stands at -13.3°C in January 2009. The mean temperature was 0.4°C below the long-term average. The frost that occurred in early January gave a coating of ice to everything but the air frost on the 27th went almost unnoticed due to the dry air prevailing and some air movement (82% humidity as opposed to 98% earlier in the month). There were 12 days without rainfall but on four occasions the daily total was in double figures (18.1mm, 17.4mm, 17.1mm and 14.9mm) with a monthly total of 107.8mm, which is 123% of the long-term average.

  • Monthly summary December 2010

    December 2010 was the coldest December that I have recorded and broke many other records. The mean temperature was 5.2°C below the long-term average. There was a record of 25 days with air frost in the month totaling a substantial 424 hours of sub-zero temperatures. There were ten days when the thermometer did not struggle into a positive figure. The extreme low of -11.7°C in the early hours of the 24th was the coldest December night since 1999 and the second coldest on record. It was the driest December since 2001 giving a total of 29.3mm, which was only 32% of the long-term average. Snow fell on a total of eight days and we endured ten days of fog.

    The year 2010 was the coldest year since 1987 being 1.1°C below the long-term average and produced a record 32 days of snowfall. The total rainfall of 672mm was just 79% (175mm below) of the long-term average. It was the third driest year after 1997 (671mm) and 1996 (594mm).

  • Monthly summary November 2010

    November 2010 proved to be a most interesting month, weather-wise. The first ten days were wet, windy and warm with a maximum of 16.6°C on the 4th and the warmest night on the 5th when the thermometer did not drop below 13.4°C although the mean minimum for this month is 3.6°C. The wettest day of the month occurred on the 7th with 10.5mm although 80% of the total rainfall fell by the 12th. The contrast began on the 18th as the winds backed into an easterly then northerly direction for the remainder of the month. The maximum on the 28th was -1.1°C followed by the coldest night when the thermometer fell to -5.8°C in the early hours of the 29th. The mean temperature was 1.7°C below the long-term average and the rainfall was 71% of the long-term average.

    A number of records were broken this month, since my records began in 1984, with the warmest November day (16.6°C) and the coldest November day (-1.1°C). It was the coldest November since 1993 and the third coldest I have recorded. There were 65 continuous hours of below zero temperatures.

    The Autumn of 2010 was the coldest since 1991 being 0.9°C below the long-term average. The total rainfall of 188mm was 77% of the long-term average.

  • Monthly summary October 2010

    October 2010 was notable for the increased number and severity of air frosts compared to recent years. There were seven air frosts, the highest frequency since 2003, and only one less than the record of eight in 1997. The lowest temperature was -3.9°C in the early hours of the 21st, this being the coldest October night since 2003, the record being -5.1°C in 1992. The beginning of the month was quite warm with mist and fog early in the day but also considerable rainfall, the maximum for the month was 16.6mm on the 1st.

    The mean temperature was exactly 1°C below the long-term average. The mean maximum was 0.4°C below the long-term mean and the mean minimum 1.6°C below the long-term average. The total rainfall of 60.3mm was only 68% of the long-term average.