Morning gloom returns

The fog and low cloud was very reluctant to disperse on Tuesday with the sun slowly gaining an upper-hand just after 13.30 that resulted in 2.8 hours of sunshine. As a result the maximum temperature of 7.9C was late in the afternoon at 15.34 and was 2.5C below the 37-year average. The UV level of 1.7 was the lowest for over a week.

The thermometer slowly fell during the evening to a minimum of 1.6C just after midnight but then recovered to a reading of 3.1C at 08.00 on Wednesday.

Wednesday at first light revealed the gloom of low cloud producing fog had returned with visibility initially down to 200m. However, a slight breeze picked up from the east for a short while when the visibility increased to over 1000m before falling back to around 500m.

The air is very still on Wednesday morning but the indication is that it has veered from the north into the east and east-southeast.

The rain radar showed a minor rain band approaching the area just after dawn, from the south, but by the time it reached this area it has fizzled out.

February 2021 Review
The month began with very mild weather that produced a maximum of 12.1C on the 2nd being 4.4C above the 37-year average. However, over the next three days the warmth slowly evaporated with cooler days and nights.

A wintry blast arrived from the 6th as the wind backed into the north then northeast. There followed eight successive nights with sub-zero temperatures, the coldest of which saw a minimum of -4.6C in the early hours of the 11th. The 9th was notable in that the thermometer did not rise above freezing all day with a maximum of -0.2C, which was 7.7C below the 37-year average. It was the coldest day since 20th January 2013 (-0.6C).

Wind chill was a factor during many days with it often feeling like -7C rather than +1 or +2C. The soil thermometer at a depth of 5cm indicated how the cold had penetrated the ground with five mornings when it showed a negative value at 08.00 the lowest of which was -2.7C on the 13th.

Earlier in the month there were reports in the press that a meteorological phenomenon called Sudden Stratospheric Warming might affect our weather. This refers to a rapid warming of up to about 50C in just a couple of days, between 10 and 50 kilometers above the earth’s surface. A Polar Vortex is present all year round rotating anti-clockwise, this girdle of winds keeps the frigid air corralled at the North Pole. It sits about 48km above the earth’s surface, around 32km above the jet stream, a meandering river of strong westerly winds around the Northern Hemisphere. When uneven warm air disrupts it from below, referred to as Sudden Stratospheric Warming, it causes the jet stream to weaken and buckle, eddies of cold air are pushed down, sending warmer air close to the poles.

While these events happen about six times per decade, according to the National Oceanic and Atmospheric Administration, many scientists claim that climate change has increased the frequency with which the polar vortex weakens and allows the cold air to run amok.

Although we had a brief, very cold spell accompanied by snow at the beginning of the month, this event did not happen over the UK this year as did occur in 2018 and referred to then as the Beast from the East. The sudden atmospheric warming brought exceptionally cold weather to Texas in mid-February when temperatures by day are normally around 15C, however they dipped as low as -18C accompanied by deep snow and freezing rain that saw many millions without power. Over 4,000 turtles were cold-stunned and rescued. At the same time Athens experienced unusually cold weather with so much snow they were able to build snowmen on the nearby beach.

During the evening of the 13th the thermometer stopped falling and began to climb again after 19.00. This was the first sign of a major change in our weather as the high pressure that had been centered over Scandinavia for several days, which brought the biting cold, began to fill and an Atlantic depression to ease in from the west.

There followed several days with exceptionally mild, moist weather brought on a brisk southerly air stream. Several days saw maxima above 11C, which were 3.8C above average followed by mild nights. The warmest occurred on the 17th/18th when the thermometer did not fall below 7.8C being 6.3C above average.

The third week in the month brought wind coming from the south on eight successive days with very warm weather on the 23rd and 24th. This was due to sub-tropical air coming all the way from North Africa crossing Iberia in its travels. As a result the thermometer rose to 14.8C on the 24th, which was 7.1C above the 37-year average. The nights were also mild with minima several degrees above the average, 9.4C on the 21st was 7.9C above the average.

The end of the month saw an anticyclone settle close to and then over the UK with very high barometric pressure. As a result we enjoyed several quiet days with little wind and many hours of welcome sunshine. The penalty with clear skies at overnight was the return of air frosts with a minimum of -2.5C during the early hours of the 26th and 27th. A pressure reading of 1042.3mb on the 27th was the highest barometric pressure since 4th January 2019.

The month overall was 0.37C above the 37-year average. It is interesting to see the variation over the years as in 1986, a cold month, the mean temperature was 2.02C below the average and in 1990 we enjoyed a very warm month with the mean temperature 7.04C above the long-term average.

February was a relatively dry month that produced 10 totally dry days and the monthly rainfall of 55.2mm, which was 12mm below the 37-year average. The river levels have been falling, not only because of below February rainfall, but that 21.1mm of equivalent rainfall was lost to evaporation from the ground, water sources and plant life. The contrasting years were an exceptionally dry February in 1986 with only 9.9mm and 2014 with 151.6mm. The long-term average is 67.2mm.

There were nine mornings when an air frost occurred, three mornings when we woke to see fog in evidence with visibility down to 200mm on two days and light snow on three days.

Winter 2020/2021
Brief statistics show that the past winter, which consists of the complete months of December to February for the ease of handling the data, was cool with the mean temperature 0.13C below the 37-year average. Rainfall for the three months totalled 266mm, which was 15mm above the 37-year average of 251mm. The contrasting years were the very dry winter of 1991/1992 when only 94mm fell and the exceptionally wet winter of 2013/2014 when 528mm was recorded.

Northeasterly wind brings back wind chill!

Monday at first light revealed that the east-northeast then north east breeze had brought low cloud off the North Sea that limited visibility to 1000m initially but as the morning progressed the fog thinned and by 11.30 the sun began to break through. The afternoon brought us 4.4 hours of welcome sunshine that saw the thermometer rise to a peak of 10.6C at 15.07, which was just above the early March average. However, the brisk breeze from this direction, gusting to 15mpg, meant that a modest wind chill was in effect making it feel a little cooler. During the evening and overnight the thermometer steadily fell reaching a minimum 0.8C at 06.24 on Tuesday however the wind chill meant it felt more like -0.5C.

Tuesday at daybreak once again revealed that low cloud, that initially limited visibility to 1000m, had by 08.00 thickened reducing visibility to 450m. The northeasterly breeze was still evident as the barometric pressure eases downwards with a current reading at 08.00 of 1030.5mb. A modest depression centred over the Bay of Biscay will continue to feed the cool moist air off the North Sea.

February 2021 Review
The month began with very mild weather that produced a maximum of 12.1C on the 2nd being 4.4C above the 37-year average. However, over the next three days the warmth slowly evaporated with cooler days and nights.

A wintry blast arrived from the 6th as the wind backed into the north then northeast. There followed eight successive nights with sub-zero temperatures, the coldest of which saw a minimum of -4.6C in the early hours of the 11th. The 9th was notable in that the thermometer did not rise above freezing all day with a maximum of -0.2C, which was 7.7C below the 37-year average. It was the coldest day since 20th January 2013 (-0.6C).

Wind chill was a factor during many days with it often feeling like -7C rather than +1 or +2C. The soil thermometer at a depth of 5cm indicated how the cold had penetrated the ground with five mornings when it showed a negative value at 08.00 the lowest of which was -2.7C on the 13th.

Earlier in the month there were reports in the press that a meteorological phenomenon called Sudden Stratospheric Warming might affect our weather. This refers to a rapid warming of up to about 50C in just a couple of days, between 10 and 50 kilometers above the earth’s surface. A Polar Vortex is present all year round rotating anti-clockwise, this girdle of winds keeps the frigid air corralled at the North Pole. It sits about 48km above the earth’s surface, around 32km above the jet stream, a meandering river of strong westerly winds around the Northern Hemisphere. When uneven warm air disrupts it from below, referred to as Sudden Stratospheric Warming, it causes the jet stream to weaken and buckle, eddies of cold air are pushed down, sending warmer air close to the poles.

While these events happen about six times per decade, according to the National Oceanic and Atmospheric Administration, many scientists claim that climate change has increased the frequency with which the polar vortex weakens and allows the cold air to run amok.

Although we had a brief, very cold spell accompanied by snow at the beginning of the month, this event did not happen over the UK this year as did occur in 2018 and referred to then as the Beast from the East. The sudden atmospheric warming brought exceptionally cold weather to Texas in mid-February when temperatures by day are normally around 15C, however they dipped as low as -18C accompanied by deep snow and freezing rain that saw many millions without power. Over 4,000 turtles were cold-stunned and rescued. At the same time Athens experienced unusually cold weather with so much snow they were able to build snowmen on the nearby beach.

During the evening of the 13th the thermometer stopped falling and began to climb again after 19.00. This was the first sign of a major change in our weather as the high pressure that had been centered over Scandinavia for several days, which brought the biting cold, began to fill and an Atlantic depression to ease in from the west.

There followed several days with exceptionally mild, moist weather brought on a brisk southerly air stream. Several days saw maxima above 11C, which were 3.8C above average followed by mild nights. The warmest occurred on the 17th/18th when the thermometer did not fall below 7.8C being 6.3C above average.

The third week in the month brought wind coming from the south on eight successive days with very warm weather on the 23rd and 24th. This was due to sub-tropical air coming all the way from North Africa crossing Iberia in its travels. As a result the thermometer rose to 14.8C on the 24th, which was 7.1C above the 37-year average. The nights were also mild with minima several degrees above the average, 9.4C on the 21st was 7.9C above the average.

The end of the month saw an anticyclone settle close to and then over the UK with very high barometric pressure. As a result we enjoyed several quiet days with little wind and many hours of welcome sunshine. The penalty with clear skies at overnight was the return of air frosts with a minimum of -2.5C during the early hours of the 26th and 27th. A pressure reading of 1042.3mb on the 27th was the highest barometric pressure since 4th January 2019.

The month overall was 0.37C above the 37-year average. It is interesting to see the variation over the years as in 1986, a cold month, the mean temperature was 2.02C below the average and in 1990 we enjoyed a very warm month with the mean temperature 7.04C above the long-term average.

February was a relatively dry month that produced 10 totally dry days and the monthly rainfall of 55.2mm, which was 12mm below the 37-year average. The river levels have been falling, not only because of below February rainfall, but that 21.1mm of equivalent rainfall was lost to evaporation from the ground, water sources and plant life. The contrasting years were an exceptionally dry February in 1986 with only 9.9mm and 2014 with 151.6mm. The long-term average is 67.2mm.

There were nine mornings when an air frost occurred, three mornings when we woke to see fog in evidence with visibility down to 200mm on two days and light snow on three days.

Winter 2020/2021
Brief statistics show that the past winter, which consists of the complete months of December to February for the ease of handling the data, was cool with the mean temperature 0.13C below the 37-year average. Rainfall for the three months totalled 266mm, which was 15mm above the 37-year average of 251mm. The contrasting years were the very dry winter of 1991/1992 when only 94mm fell and the exceptionally wet winter of 2013/2014 when 528mm was recorded.

Sunday was the last of the sunny days for a while

Sunday brought 7.8 hours of warm sunshine that saw the thermometer rise to 12.2C, which was 4.5C above the 37-year average. However, the wind having veered further into the east and picked up speed with a maximum gust of 18mph, meant it felt a little chilly out of the sun.

Cloud drifted in from the North Sea overnight that meant a frost free night with a minimum of 2.3C. However, the low cloud meant a foggy start to Monday with visibility initially restricted to 1,000m.

The high-pressure has been easing away and lost 10mb of pressure with a current reading at 08.00 of 1032mb so the weather is on the change.

Calm, sunny days under high-pressure

The intense anticyclone still over the UK produced another calm day on Saturday with very little breeze that on just one occasion peaked at 9mph. This was the second consecutive day with a maximum gust of 9mph, the lowest the lowest since 9th January (7mph). The sunshine on Saturday was slightly down on the Friday total with 7.1 hours. The breeze, such as it was, had veered into the east-northeast. The thermometer showed a maximum of 11.8C again being 4.1C above the average.

The past night was slightly less cold than the two previous nights with a minimum of -1.0 that occurred briefly an hour before dawn, which was 2.5C below the 37-year average. By 08.00 on Sunday, under the influence of continuous sunshine, the thermometer read 0.6C.

The centre of the anticyclone has edged eastwards to be over The Wash with a pressure of 1038.5mb at 08.00.

Centre of anticyclone almost overhead!

With the intense high pressure overhead on Friday it was not surprising that we had a day of sunshine, 7.4 hours, and light winds, a maximum gust of just 9mph. The minimal wind movement was from the west or northwest that meant a slightly cooler day than of late with a maximum of 11.8C. However, this was still 3.1C above the 37-year average.

Thursday into Friday gave us four hours of sub-zero temperatures but the past night produced just over nine hours of sub-zero temperatures as the thermometer dropped below freezing at 22.47 Friday evening.

Saturday dawned with strong sunshine again as the anticyclone is still firmly positioned overhead with the centre now just of the South Wales coast. The barometric pressure at 08.00 read 10.42.3mb, which is the highest pressure since 21st January 2020 and should provide another sunny and calm day. At 08.00 the temperature had risen to -0.8 and by 08.15 was above freezing. The ground temperature at a depth of 5cm continues to fall with a reading this morning of 1.2C, the lowest since 14th February.