Windrush Weather

Category: Commentary

  • More sun and more thick fog in very still conditions.

    The sun eventually got to work on the fog on Thursday morning and gave us 4.3 hours of strong sunshine that pushed the thermometer, again, above the average with a maximum 13.5C (+3.5C).

    The high barometric pressure had reduced 5mb, as the centre of pressure drifted southwards, but still gave exceptionally still conditions with one maximum gust of just 6mph. I had to go back through the records to find a day with even less wind and that was on the 18th January 2017 when the strongest movement of air was 5mph.

    Last night was a repeat of the previous night as the clear skies and still conditions caused fog to form again with visibility even further reduced and down to 90m at dawn.

    The thermometer fell away as expected in clear skies overnight to a minimum 4.9C, recovering as the fog formed to 6.9C at 08.00.

  • Sunshine by day, clear skies by night, then fog. Also October summary

    Slowly the cloud thinned on wednesday and the sun came through with 3.80 hours of strong sunshine that boosted the temperature to a maximum of 14.4C, which was 4C above the early November average.

    The clear skies overnight meant that the thermometer dropped rapidly to a minimum of 0.7C, being 3C below the November average, at 02.40 this morning. Thereafter the temperature rose slowly to 2.2C at 08.00.

    Fog formed in the early hours and at dawn visibility was down to 100m.

    Summary for October 2017

    Another rainfall record has been broken, exactly twelve months after the last occurrence. This time the record is again for lack of rain.

    With just 31.3mm of precipitation, October has been the driest month since my records began in 1984, a period of 34 years. The previous low record was set in 2016 with 31.5mm when the average was 86.4. This means a short fall of 55.1mm as compared to the long-term average or just 36%.

    The heaviest twenty-four rainfall total was 10.2mm on the 19th, this midway between the wettest period of the 17th to 24th, being 73% of the monthly rainfall. We enjoyed 14 totally dry days.

    The wettest October occurred in 2004 with 159.3mm, which was almost twice the average.

    It has been the ninth driest January to October period I have recorded with a total of 572mm. The extremes for these ten months are 409.0mm in 1996 and 920.6mm in 2014.

    It is interesting to note that the equivalent moisture lost to the atmosphere from ground sources and plant life during the month was 27.9mm. Therefore most of the rain that fell in October has been offset by evaporation.

    Due to the Jet Stream providing a conveyor belt of frequent depressions the wind has been predominantly between south and west, bringing mild air, sometimes from as far south as the Azores.

    This mild, moist air has meant a relatively warm month with the mean temperature 1.4C above the 33-year average. There were 21 days with above average maxima. The peak temperature of 18.9C was recorded on the 16th, some 4.3C above the average.

    The stormy period around the 21st meant very strong winds gusting to 40mph. However, at the end of the month the opposite was true as a couple of very still days occurred with hardly a breath of wind such as a maximum of just 7mph on the 30th.

    We suffered one air frost, that on the night of the 30th, when the thermometer fell to -0.5C, cold enough to bring to an end the wonderful colour of bedding plants that we have enjoyed for so many months.

    During the month we have enjoyed 82.3 hours of strong sunshine, the sunniest being 5th with 7.9 hours followed by the 7.36 hours on the 25th. There were several dismal days of thick cloud, which were often low enough to drape the tops of the Downs in mist giving us eight sunless days.

    Fog was recorded on three days.

  • October was the driest since records began in 1984

    Tuesday was a sunless day although the wind, having backed into the southwest, meant a slightly warmer day with a maximum of 12.4C, being 2.2C below the 33-year average. The minimum overnight was 6.7C, some 3C above average.

    October Summary

    Another rainfall record has been broken, exactly twelve months after the last occurrence. This time the record is again for lack of rain.

    With just 31.3mm of precipitation, October has been the driest month since my records began in 1984, a period of 34 years. The previous low record was set in 2016 with 31.5mm when the average was 86.4. This means a short fall of 55.1mm as compared to the long-term average or just 36%.

    The heaviest twenty-four rainfall total was 10.2mm on the 19th, this midway between the wettest period of the 17th to 24th, being 73% of the monthly rainfall. We enjoyed 14 totally dry days.

    The wettest October occurred in 2004 with 159.3mm, which was almost twice the average.

    It has been the ninth driest January to October period I have recorded with a total of 572mm. The extremes for these ten months are 409.0mm in 1996 and 920.6mm in 2014.

    It is interesting to note that the equivalent moisture lost to the atmosphere from ground sources and plant life during the month was 27.9mm. Therefore most of the rain that fell in October has been offset by evaporation.

    Due to the Jet Stream providing a conveyor belt of frequent depressions the wind has been predominantly between south and west, bringing mild air, sometimes from as far south as the Azores.

    This mild, moist air has meant a relatively warm month with the mean temperature 1.4C above the 33-year average. There were 21 days with above average maxima. The peak temperature of 18.9C was recorded on the 16th, some 4.3C above the average.

    The stormy period around the 21st meant very strong winds gusting to 40mph. However, at the end of the month the opposite was true as a couple of very still days occurred with hardly a breath of wind such as a maximum of just 7mph on the 30th.

    We suffered one air frost, that on the night of the 30th, when the thermometer fell to -0.5C, cold enough to bring to an end the wonderful colour of bedding plants that we have enjoyed for so many months.

    During the month we have enjoyed 82.3 hours of strong sunshine, the sunniest being 5th with 7.9 hours followed by the 7.36 hours on the 25th. There were several dismal days of thick cloud, which were often low enough to drape the tops of the Downs in mist giving us eight sunless days.

    Fog was recorded on three days.

  • Coldest day for six months & still on course for record dry month

    With the anticyclone centred almost overhead yesterday it was not surprising that there was little wind. For long periods the anemometer did not stir with the maximum gust during daytime hours of 6 mph and just after 2am this morning a gust of 7 mph.

    The air, coming from the northwest, meant a cool day, in fact it was the coolest day since 27th April. The thermometer reached a peak of 11.0C, being 3.6C below the average and fell away to 2.8C just before 9pm last night when with increasing cloud it reversed and picked up 0.5C. Just after midnight, the much thicker cloud that had arrived meant an increase of 4C by dawn so that the thermometer at 08.00 read 8.3C.

    This morning is overcast with high cloud and no sunshine.

    The total rainfall for October is 55mm below the 33-year average with just 31.3mm of precipitation this month and with evaporation from ground sources and plant life of 27mm, it is no wonder that our local rivers are running so low.

  • First air frost of season but still driest October since 1984 – just.

    The brisk northerly winds on Sunday, gusting to 23mph, pegged back the temperature even though we had 3 hours of strong sunshine. The thermometer slowly crept up to a maximum of 13.4C at 13.03, being 1.2C below the average, but then began to fall to around 10C for the rest of the afternoon before, in clearing skies, falling steadily to a minimum of -0.5C at 07.10.

    Hazy sunshine greeted us at dawn this morning with the sun slowly strengthening after 8am

    Sunday was another dry day so the total precipitation for October is still 31.3mm when the record low was set in 2016 with 31.5mm. That was the driest October since this station commenced recordings in 1984.

    The barometric pressure this morning at 08.00 reads 1031.7mb and is still rising.