Sunshine and showers – again!

At least the morning was dry on Monday that allowed the thermometer to rise to a peak of 13.9C at 12.25, early in the day before the cloud built up, however, this was 0.2C below my 40-year average for April. The rain set in during the afternoon, heavy at times, producing 9.9mm of precipitation. The cloud again meant a mild night with a low of 6.3C, being 2.6C above the long-term average.

There were very brief glimpses of sunshine after sunrise on Tuesday that were soon obliterated by thick cloud.

There are five centres of low pressure surrounding the UK so another unsettled day is in store and probably for the next few days as the jet stream continues to feed these depressions across the UK on a rainy southwesterly air stream.

March 2024 Review

The new month got off to a chilly start. Although the wind on the 1st came from the south, the very cool air originated from a region just below the Arctic and travelled south off the west coast of Ireland before changing direction by 180 degrees, thanks to a depression over the south of England. The slow-moving area of low pressure deposited 16.2mm of precipitation including a brief, sharp squall that contained small hail.

The second week saw temperatures rise thanks to an anticyclone over the Continent rotating clockwise, and a depression in the Atlantic rotating anticlockwise, that between them channelled very warm, moist air over the UK on a most south-westerly breeze. Almost every day produced a modest rainfall total, 8.3mm on the 11th was the wettest day of this period.

The warmest day was recorded on the 14th with a maximum of 14.6C being 4.0C above my 40-year average and the warmest day since 18th November. The nights were very mild thanks to the warm air that did not escape due to a thick blanket of cloud that minimised warmth dissipating into the atmosphere.

The UV level peaked at 3.6 on the 14th, which took it into the ‘Moderate’ level for the first time since 25th September.

The third week of March saw temperatures rise significantly as an airstream from the southwest brought very warm days, often 4C to 5C above my 40-year average. A peak of 15.9C was logged on the 17th, which was the warmest day of the month and the warmest day since 20th October.

By the 22nd there was a dramatic change as the wind swung into the northwest bringing Arctic air that saw maxima drop for two days. During the afternoon of the 23rd small hail, less than 5mm in diameter, was observed on two occasions whilst the air temperature dropped 5C and the wind in the squall gusted to 28mph.

Storm Nelson, named by the Spanish Metrological Service as they suffered the greatest impact, arrived at the end of the month. This brought very wet days and very strong winds with a peak of 32mph on the 27th. From 08.00 on the 27th to the same time on the 28th a total precipitation of 21.7mm was recorded that contained soft hail, called graupel, being observed at 09.35. This was the wettest twenty-four hours since 17th February (27.1mm). For the subsequent 25 minutes the thermometer dropped from 8.4C to 3.0C.

The intense depression gave us a minimum pressure of 971.8mb early on the 28th, the lowest barometric pressure since 9th February (974.5mb).

The presence of several low-pressure systems in the eastern Atlantic meant an unsettled finish to March.

The month was memorable for being unsettled throughout with no extended dry or warm spells. There were only 10 dry days compared to my 40-year average of 16 during March. The rain relented on two occasions when three consecutive days were dry, once in the first week and again in the third week.

The monthly rainfall of 122mm was 199% of my 40-year average or +60.6mm. It was the third wettest since my records began in 1984, just two were wetter, both in recent years, with 130.9mm in 2018 and the exceptionally wet March last year with 163.3mm.

The period of January to March has over forty years produced an average of 220mm of precipitation compared to the first three months of this year when 368mm was recorded.

Due to the flow of moist, warm air, often from the Atlantic, the maximum average temperature was 1.0C above my 40-year average and the night-time minimum average was a significant 1.8C above the long-term average. The unsettled weather also meant very few frosts occurred, just four at the beginning of the month when the average over forty years is eight.

The warmest day occurred on the 17th with a maximum of 15.9C compared to the average of 10.6C. The coldest night was logged in the early hours of the 3rd when a low of -2.5C was observed against the average of 2.52C.

The graphs on the website, that are below the statistical data for each month, season and year, clearly show the upward trend in temperatures. I wonder if the recent occurrence of the wetter months of March will continue.