A warm start to February

The thermometer rose well above average (+5.5C) on Tuesday to reach a maximum of 13.2C in the modest westerly flow of air. The UV level rose to 1.3, the highest since 5th November confirming that the sun is slowly getting stronger.

The thermometer did not sink below 7.1C overnight making it a very mild night, this low was 5.6C above the 38-year average

There was a very light shower in the early hours of Wednesday starting just before 05.00 amounting to 0.3mm.

Variable cloud greeted the start of Wednesday with glimpses of sunshine between the broken cloud. The barometric pressure remains high with a reading of 1024.5mb at 08.00.

January 2022 Review
The month began with unusually high temperatures as a maximum of 12.9C was set on the 1st, which was 5.9C above the 37-year average. This was not a record for a January, that was set on the 1st January 2015 when a peak of 14.1C was recorded. The warm air was brought on a south-westerly breeze that arrived from the Azores.

Just days later the thermometer dropped significantly as the wind swung into the north then northwest with a low of -5.4C that was recorded in the early hours of the 6th.

Snow was observed; light at first then became heavier, on the 7th at 14.50. The temperature rose overnight and all trace of the wet snow had disappeared by morning.

An anticyclone then eased in over the UK or very close by, and became more or less resident for several days from the twelfth. The days were noticeable for the very calm conditions with little wind movement, In fact, for several days there were many hours when no air movement activated either the high or low anemometers. There were days when the maximum movement of air was 4 or 5mph and down to a limp 2mph on the 14th.

The explosion of the volcano in Tonga on the 15th produced an atmospheric shock wave that went around the world twice. Sensitive barometric pressure gauges, such as those at the regional Metrological Office at Brize Norton, recorded a rapid increase of 1mb followed by a rapid decrease of almost twice that amount just before 19.00 hours. Subsequent waves were also evident for at least 12 hours afterwards. The initial shock wave travelled some 16,000 km from the volcano at the speed of sound – close to 310 m/s.

My barometer also recorded statistical and graphical data that showed just that effect. Weather satellite data calculated that the plume reached 35 miles above the earth’s surface.

The persistent high pressure meant and still conditions produced a thick fog on the 18th. Initially, the fog was seen to the northwest of Marlborough but by 08.30 it had drifted over the area and began to thicken, limiting visibility to 100m at 09.30

A replacement anticyclone began to assert itself on the 20th with pressure building again and producing a very sunny day with 5.4 hours of strong sunshine and the highest UV level for two months. However, we paid the price for overnight clear skies as the thermometer fell steadily to reach a minimum of -6.4C at 08.00 on the 21st. This was the coldest night since 1st January 2021 when -6.7C was recorded.

After two weeks of very quiet weather, little or no wind on many days, Storm Malik arrived to the north of the UK on the 29th that brought the strongest gust of wind since the 6th with a peak of 27mph. The Danish Metrological Institute named this storm as it’s greatest impact was on that area of the Continent. They are part of the northern group of European nations that name storms , which impact them the greatest. We experienced winds gusting to 36mph as a result of Storm Malik, which was quickly followed but Storm Corrie, named by the Metrological Office. They link with Metrological Eireann and the Netherlands Metrological Institute. The storms are named alphabetically.

January brought us extremes of temperature, from the warmest January day and night I have recorded on the 1st, 12.9C and 11.7C respectively. There were an increased number of air frosts, 18 in total when the average is 11 with a low of -6.4C in the early hours of the 22nd.

The mean temperature was 0.5C below the 37-year average.

It has been a very dry January with a total of just 28.3mm, which is just 31% of the 37-year average or a significant deficit of 62.3mm. It was the fourth driest I have recorded since the station opened in 1984 with 1997 the driest January that produced just 9.4mm.

Although we have just experienced a very dry January, new analysis of the latest climate science shows that future extreme rainfall could be more extreme than previously thought.

The impacts of extreme rainfall could be more frequent and severe than had previously been thought at the last UN climate conference, COP25, two years ago in Madrid. A new generation of climate models have provided a new light to look at the recent catastrophic floods seen across the world in the last year and what could be expected in the future.

Recent flood events show that there is a greater urgency than had previously been thought about reducing emissions and preparing societies to make them more resilient to extreme rainfall events. These new climate projections are helping organisations and people improve their resilience to flooding.

In addition to the increase in high intensity rainfall, the number of days when 80mm of rain falls in 24 hours could become 4.5 times more likely by 2070 under a high emissions scenario.

Flooding events over the past 12 months include devastating flooding in central Europe during summer 2021, flooding of the London underground in July 2021 and in Zhengzhou, China in the same month. In the central Europe event, some parts of Western Europe received up to two months worth of rainfall in two days. A recent climate attribution study has shown that climate change made the one day rainfall in this region more intense – increasing the rainfall by between 3 and 19%.

In addition to increases in hourly rainfall intensity, the latest generation of high-resolution climate models also show more, slower-moving storms, which can lead to high rainfall accumulations, with high rainfall rates sustained over several hours. This has serious consequences for changing flood risk as was seen in central Europe in the summer. A recent study by the Met Office and Newcastle University scientists showed that slow-moving storms with the potential for high rainfall accumulations are projected to be 14 times more frequent over land across Europe by 2100 under a high emissions scenario where global warming reaches 4.3°C.

Met Office climate scientist, Professor Lizzie Kendon, said: “Recent developments in high resolution climate projections are letting us examine changes in future extreme rainfall in unprecedented detail. We’re seeing that extreme rainfall events are being made both more frequent and more intense as a consequence of human induced climate change. Recent flooding events around the world show the devastation that intense rainfall can cause. By reducing our greenhouse gas emissions, the worst impacts can be avoided, but organisations and individuals need to be resilient to the changes in our weather that we’re already committed to”.

Because of the global warming that’s already taken place, rainfall extremes have already started to change. Science Fellow in Climate Attribution at the Met Office Hadley Centre, Professor Peter Stott, said: “Climate change is no longer just an issue about the future. With the atmosphere having already warmed by around 1°C it can hold roughly 7% more moisture than it would have in the pre-industrial period, leading to more extreme rainfall events. As well as the chances of more extreme rainfall in the future we’re seeing the influence of climate change on the weather we’re experiencing now.”

Extreme weather events are nothing new, but the frequency with which they are occurring is changing. For the UK, five of the 10 wettest years on record have happened since 2000, and the flooding in London in July 2021 is illustrative of the type of event we expect to increasingly see in future.