With a maximum of 10.4C and a minimum of 5.2C January arrived with a continuation of the mild weather. These extremes were 3.4C and 3.9C above the 38-year average respectively. The last twenty-four hours also broght more rain with a daily total of 4.2mm
Monday arrived with brighter and drier weather as a transitory ridge of high pressure gives us a fine, dry day with several hours of welcome sunshine after the previous wet, murky days.
December 2022 Review
It was a shock to the system that December arrived with winds from the northeast, a cool direction, that depressed temperatures that followed November, when most days and nights had above average temperatures. Meteorological Winter starting on the 1st lived up to its name.
The 1st produced a minimum of -1.0C and an air frost, subsequent maxima and minima were well below average. An intense high-pressure system over Russia meant that north-easterly winds persisted until the 6th, when the anticyclone waned and was replaced by a low-pressure system over Scandinavia.
Not only was the first week cold but thick, low cloud meant very dull, gloomy days with fog on the 1st and 2nd that limited visibility to 200m. Sunday the 4th was the worst of those days when for the first time in a year no evaporation was recorded due to the high humidity and brief light drizzle around midday.
The brisk winds from the northeast produced a windchill that on several days meant that outside it felt two or three degrees colder than indicated on a thermometer.
The Arctic Maritime airmass arrived with a vengeance on the 7th as the wind backed into the north. The daytime high of 2.8C on the 8th was 5.3C below average following a minimum of -6.1C in the early hours. However, the cold then intensified with a minimum of -7.4C in the early hours of the 9th making it the coldest night since February 2019. During this period we were in between the low pressure system to the east circulating anticlockwise and high to the west circulating clockwise, hence the northerly wind direction.
From the 8th until the 16th the country was in wind drought. Throughout this period the UK and western Europe were calm, with barely a breeze. During many days the anemometer was becalmed and when it was encouraged into life by the slightest breeze a maximum movement of 6mph was recorded on two days.
The cold became intense around the middle of the month with two days when the thermometer did not rise above freezing with maxima of -0.2C and -0.4C on the 14th and 15th respectively. These two cold days were followed by two intense overnight frosts with minima of -9.4C and -9.1C in the early hours of the 16th and 17th.
Another indication of the prolonged and intense cold was the series of readings taken at a soil depth of 5cm using my meteorological, right-angled soil thermometer. There were ten mornings when the temperature at a depth of 5cm at 08.00 was below freezing with a sequence of readings from the 13th to the 17th, being -0.6C, -1.3C, -3.1C, -3.8C and -2.8C.
A battle between the cold Arctic Maritime air from the previous week and mild Tropical Maritime Atlantic air from near Madeira took place during the 18th when a rapid transition took place. The thermometer saw a rise from -1.5C to 12.1C during the twenty-four-hour period banishing the very cold and dry weather that came from the north or northeast. However, the change in our weather was accompanied by almost continuous rain from the Sunday well into Monday. It started with sleet, that as the temperature rose produced icy conditions on flat surfaces, before heavier rain and warmer air brought a thaw. This period produced 28.1mm of precipitation, the wettest day since October.
The balmy 12.1C on the 19th at 08.00 was the warmest start to a day at that time since 7th November. However, we endured another day with almost continuous rain for twenty-four hours with a daily total of 29.8mm. The thermometer slowly rose as the day progressed to reach a maximum of 12.9C, the warmest day since 14th November.
On the 22nd an array of weather fronts could be seen on the Atlantic synoptic charts indicating more rain and cloud. In fact at 08.00 the humidity was 100%, not recorded for a long time, which was due to the cooling overnight and thick drizzle and low cloud.
The latter end of the month was notable for the chain of weather fronts arriving from the Atlantic bringing wet and windy weather but very mild.
The mean temperature for December was 0.9C above the 38-year average. The warmest day occurred on the 19th when the thermometer rose to 12.9C being 4.8C above the average. There were several very cold nights but around dawn on the 16th the thermometer dropped to a bone chilling minimum of -9.4C.
It was an unusual month for rainfall. There were almost 17 consecutive dry days from the 1st until the 17th with the exception of just 0.2mm on the 11th. From that date onwards precipitation was recorded on every day until the 31st. The two exceptionally wet days were on the 18th and 19th with 28.1mm and 29.8mm respectively but considerable totals were also recorded on the 27th and 31st with 16.5mm and 15.4mm respectively. The monthly rainfall amounted to 131.1mm, which was 39.4mm above the 38-year average and the wettest December since the record was set in 2013 with 157mm.
Analysing the diurnal range of temperatures, the difference between the day and night extremes, I found a rising trend of variation. In the 1990s the average variation was 11C but in recent years that has steadily risen to 14C.
2022 Annual Review
It was the warmest year that I have recorded since the station was set up in 1984 being 1.1C above the 38-year average and just beat the previous high of +1.0C in 2020.
Memory will remind us that the earlier months in 2022 were very dry but some adjustment came in the wet months of October to December. The annual precipitation was 712mm being 148mm below the long-term average and the driest year since 2011. The record years were in 1996 with just 594mm and 2002 with 1146mm.
General Interest
During the past year wind has produced 28% of the UK electricity but in mid-December this dropped to only 3.4% of the country’s demand. During this slack pressure period there were anxieties that there might be insufficient electricity produced to balance the considerable demand during the cold and dark days.
The scientists calculate that after 2050 winds will weaken significantly in the northern hemisphere. This is called global stilling and caused by the rapid warming of the Arctic, which is narrowing the temperature difference with the tropics, a gap that drives the wind.
Nasa has just launched a satellite that’s expected to transform our view of water on earth.
The mission will map the precise height of rivers, reservoirs and lake, track ocean surfaces at unprecedented scales.
It should improve flood and drought forecasts, and help researchers better understand how the climate is changing. British scientists have been asked to help set up the spacecraft using the Bristol Channel as a benchmark, which has one of the highest tidal ranges in the world.
The UK researchers are putting a suite of sensors in the Bristol Channel to ‘ground truth’ the observations made by the satellite as it flies overhead at an altitude of 890km.
The exercise should be able to resolve all rivers at least 100m wide and see all lakes larger than 15 acres. It will be surveying millions of lakes rather than the previous 10s of 1,000s. It will see the bulges and depressions in the water surface associated with currents and eddies that pull heat and carbon dioxide out of the atmosphere, tempering the impact of global warming.
Outlook
The UK Metrological Office have recently forecast that 2023 will be warmer than 2022. Predictions suggest that it will be the 10th year in a row that the global temperature is at least 1C above average. The Met Office explained that a cooling effect known as La Nina will likely end after being in place, unusually, for three years – part of a natural weather cycle. La Nina is a weather pattern when cooler-than-average sea temperatures in the Pacific, along the tropical west coast of South America, lower the average global temperature.