The blocking high-pressure over the near continent has exerted its influence over the UK for many, many days with stagnant air and on some days thick fog. Just after 10am yesterday the barometer indicated the beginning of the decline in barometric pressure that has continued since with the lowest pressure this morning for more than two weeks.The consequence is that the persistent fog of yesterday, with visibility down to 150m that did not begin to lift until midday, has left us.
Overnight the wind has begun to pick up after so many calm days.The thermometer has hovered around zero most of the night, minimum of -0.3C, but the strengthening wind has meant significant wind chill making it feel more like -3C. The strongest gust before readings were taken at 0800 was 20mph just after 7am with the thermometer reading 0.1C.
This morning is overcast with low cloud and much lower humidity as the strengthening wind has brought the drier and cooler air from the continent.
Author: Eric Gilbert
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At last, blocking anticyclone begins to decline
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Highest UV level since November
Yesterday brought 1.80 hours of strong sunshine, which pushed the maximum temperature to 8.2C, the highest for a week and the UV level at 0.9 was the strongest since 15th November. Another day without rain and still under the influence of the blocking high pressure over the near continent that meant virtually no movement of the stagnant air, the highest reading on the anemometer was 8mph.
Fog returned in the evening and at dawn visibility was down to 150m and took until midday today before it started to lift very slowly.
After five days with the ground frozen at a depth of 5cm, the reading today was 0.2C. -
Number of air frosts above average for January
The often hazy sky yesterday obscured the full strength of the sun for much of the day with only 0.58 hours of strong sunshine, although the thermometer did rise to its highest for a week with a maximum of 6.2C, still below average for January. It was another day with virtually no movement of the air for long periods with three occasions when the anemometer registered a maximum of just 6mph.
Overnight the thermometer dropped to -3.6c at 05.20 but thin cloud since that time has meant the temperature has risen to -1.7C at 08.00. There was no fog at the time when readings were taken.
The average number of air frosts for January, over the past 32 years, is 11 with the total for 2017 being 14 to date. The record for air frosts occurring in January was set in 1985 and 2010 when there were 22 days when we awoke to below freezing mornings. -
130 hours of sub-zero temperatures this month, so far!
The thermometer climbed a little higher yesterday, to a maximum of 6.0C at 14.26. It was another day of very light winds, maximum of 10mph and hours without any movement of the air. The sun was a little hazy at times but sill logged 5.26 hours of strong sunshine. Not surprisingly, with a clear sky, the thermometer then began a steady decline until a minimum of -3.8C was reached at 00.30 this morning when there was an about turn and the temperature gradually recovered to a low of -0.7C at 08.00
There have been 130 hours of sub-zero temperatures this month with the last two days recording 18 and 16 hours respectively below freezing. Freezing fog developed late evening with visibility down to around 200m. By dawn this freezing fog had developed into moving banks that varied in visibility from 200m to 1000m. -
2.7C, that was the warmest yesterday – Brrrr!
The thermometer struggled to reach a maximum of 2.7C yesterday, just after 2pm. It then drifted downwards again and started to freeze very early just before 5pm. After an initial halt to the lowering temperature in early evening it reached a mimimim of -4.3C at sunrise this morning.
The very cold days and nights have meant that the frost has permeated deep into the ground and my soil thermometer, at a depth of 5cm, is reading -3.2C at 08.00 this morning. The sun today is rising into a blue sky after 6 hours of strong sunshine yesterday (100 W/sq.m.).