Royston (Iceni) Weather Station
Daily Weather Observations - November 2001
November 2001 Weather Review
The November weather in Royston was a little milder, drier, and sunnier than normal, and in consequence November was a quite reasonable Autumn month, with no notable extremes.
Commenting first on the November sunshine, it was a very sunny first half of the month, and by 15th a sunshine total of 55.3 hours had been accumulated. However, a period of ‘anticyclonic gloom’ then set in and the next 4 days were completely sunless, albeit mostly dry.
The remainder of the month did not fare much better and a sunshine total of only 22.0 hours was registered for the period 16th/30th. Even so, the total sunshine for the month of 77.3 hours still managed to exceed the average by 16%.
The sunniest day of the month was 1st with sunshine of 8.0 hours, with the next highest daily total being 7.9 hours on 3rd. The number of days in the month on which no sunshine at all was recorded was 7.
Although it was a milder than average month it was the mildest November since 1999 only. Of much greater significance is the fact that this was the 7th November in the last 10 years with above average temperatures.
The highest temperature recorded in November was 14.5°C on 2nd, but this was the lowest November monthly maximum temperature since 1987. The lowest temperature in the month was –0.9°C, which was recorded on each of 10th, 14th and 23rd. The lowest grass minimum temperature during the month of –3.8°C occurred on 15th. Totals of 4 air frosts and 7 ground frosts were recorded in November.
The mean daily maximum and minimum temperatures in November were 10.3°C (0.8°C above average) and 5.0°C (0.4°C above average) respectively. The mean earth temperature at 30 cms depth as measured at 0900 GMT daily was 8.4°C. The highest earth temperature value in the month was 10.9°C on 1st, and the lowest 6.6°C on 16th.
After the very wet October in Royston, the November rainfall in contrast totalled less than 1/3 of the October value, and was also only 1/3 of the November rainfall recorded last year. Although the November rainfall total of 42.3 millimetres was below normal at 81% of the 30 Year (1971/2000) average it was, in fact, the driest November since 1999 only.
The number of "rain days" (0.2 millimetres or more) in November was 15, whilst the number of days with 1.0 millimetre or above was 10. The wettest day of the month was 7th, with a somewhat modest total of 7.9 millimetres, whilst 29th recorded 7.8 millimetres.
A light early season snowfall occurred in the early morning of 9th, but did not last long on the ground after sunrise. A few flakes of snow were observed to fall the previous day, on 8th.
Rainfall duration over the month was 51.8 hours.
Much of the 3rd week of November was very calm, and, unusually, daily (00/00 GMT) mean wind speeds of 0.0 mph occurred on 16th, 17th and 19th. In reality, a few low speed wind gusts were measured on these days, but were not enough to raise the mean wind speed to 0.1 mph (to nearest decimal point).
The highest wind gust speed in the month was 39 mph on 21st and 27th. The highest daily (00/00 GMT) mean wind speed was 11.7 mph on 21st.
Daily wind directions showed a heavy bias to winds from the west and south-west. The analysis of daily wind directions as observed at 0900 GMT was NORTH 2 days, NE 0, E 0, SE 0, S 1, SW 9, W 10, NW 3 and CALM 5.
November was a fairly anticyclonic month and the mean MSL air pressure of 1023.9 mB was some 8 mB above average. The highest pressure value recorded in the month was 1042 mB on 16th, and the lowest value recorded was 995 mB on 8th.
The mean relative humidity in November was 88.8%. The highest daily (00/00 GMT) mean relative humidity value in November was 97.5% on 29th, whilst the lowest daily mean value was 80.5% on 5th. The absolute lowest relative humidity reading in the month was 59% at 1335 GMT on 4th.
As regards the Autumn season (September/November) as a whole, the mean daily maximum temperature was 14.9°C (0.8°C above average), whilst the mean daily minimum temperature was 1.3°C above average at 8.8°C. Total Autumn rainfall was 249.1 millimetres (150% of average) and sunshine 320.7 hours (101% of average).
Richard Barker
Richard Barker
Met. Observer, Royston (Iceni) Weather Station
5th December 2001
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