Sunday was another mainly gloomy day but the thermometer did rise above average, just (+0.5C). However there was a shower at 15.00 that produced another 1.0mm of precipitation that took the monthly total to 75.7mm, which was 132% of the 39-year average.
The last night has been mild with the thermometer not dropping below 9.0C, which was 5.3C above average.
Monday dawned dull and gloomy again under a constant sheet of thick cloud. The wind has veered into a cooler direction and coming currently from the northwest.
April 2023 Review
After the very wet end to March, thankfully Storm Mathis moved away, and we had a drier interlude although the wind from a northerly quadrant meant cool days with below average maxima.
A ridge of high pressure, extending from Norway to Portugal, meant that we enjoyed three dry days from the 2nd to the 4th with many hours of glorious sunshine. However, clear nights brought cold nights with a frost that gave a minimum of -2.4C in the early hours of the 4th , the coldest night of the month.
All change again as gusty showers on the 6th produced 6.2mm of precipitation, including two hail showers at 12.55 and 16.40, the latter shower was heavy with hail up to 3mm in size that briefly completely covered the ground.
The changeable weather then brought another brief ridge of high pressure from the 7th to the 9th with wall-to-wall sunshine again and maxima above average.
The 11th and 12th were memorable for the arrival of a complex low pressure system. This was the first of the named storms in the 2022-2023 year and referred to as Storm Antoni initially by the UK but claimed by France, I know not why, as it was predominantly over the UK, but subsequently referred to as Storm Noa named by Météo France. Contained within the overall depression were six separate centres of low pressure. This disturbed period again produced much rain with 10.8mm on the 11th. These disturbed periods also brought strong, gusty winds with a peak of 36mph on the 11th.
A ridge of high pressure built from Scandinavia to Northern France on the 17th that brought a change in the weather from predominantly wet and cloudy to more settled conditions.
A significant change in our weather pattern occurred on the 24th. The depression that had brought modest rainfall on the previous three days had moved eastwards to centre over Denmark. As a result, the winds circulating anticlockwise, as they do around a low pressure, brought Arctic air streaming down across the country, originating from north of Greenland.
The 27th was notable for being the dullest day in April with minimal solar energy due to a gloomy morning and nine hours of rain starting at 13.00. With a couple of showers early on the 28th the daily rainfall amounted to 11.4mm, that made it the wettest day in April.
The warmer air eventually arrived late on the 27th after several warm fronts had crosses the country. It resulted in the warmest start to a morning at 08.00 in April. The warmer night also meant the soil temperature at a depth of 5cm read 11.3C, the warmest at 08.00 since 14th November.
The warmest day of the month was the 29th with a maximum of 18.3C. This peak was 4.2C above the 39-year average making it the warmest day since 29th October.
The mean temperature for April was 0.4C below the 39-year average and equally split between day and night extremes.
The monthly rainfall of 75.7mm was 134% of the 39-year average or +19mm. The extreme years were set in 1984 with 2mm and the very wet April of 2000 when 165.2mm was recorded.
There were just five days when an air frost occurred, the coldest morning occurred on the 4th with a low of -2.4C.
It was another rather gloomy month, not as bad as March, with 277 hours of global sunshine that was 15 hours below the average and the lowest since 2018.
What might the next few months bring?
The majority of April, and certainly March, were cool so we would all welcome some warmer weather soon. I wonder if an El Niño might assist with this wish. The evidence is that the UK could be warmer than the previous three years if the predictions are realised.
Reference has been made in the media recently about a phenomenon called El Niño. I decided to do some research and have a better understanding of this weather event.
The El Niño Southern Oscillation (ENSO) is a weather phenomenon, shortened to El Niño, that occurs in a region of the eastern Pacific Ocean near the equator. It usually happens once every two to seven years.
The name El Niño means ‘the boy’ in Spanish compared to ‘the girl’, or La Niña. But where La Niña brings colder surface temperatures, El Niño means things are heating up – a condition that affects the climate worldwide.
The phenomenon’s original name was El Niño de Navidad and was named by south American fishermen in the 1600s who noticed the unusually warm water in the Pacific that define an El Niño season. They named the warm waters after Jesus, literally the ‘the little boy of Christmas’ because El Niño typically peaks in December, around Christmas time. The nickname stuck around for 100s years but not really named until the 1980s according to NOAA (National Oceanic and Atmospheric Administration).
How might this impact our weather?
There are likely to be fewer hurricanes and other tropical cyclones in the North Atlantic besides a global warming of 0.2C, it is suggested.
On Thursday 15th, NOAA (National Oceanic and Atmospheric Administration) issued an “El Niño Watch” meaning chances of the formation of that weather pattern appear more likely than not. However, this year Scientists are warning of a potential “super El Niño’
How El Niño works.
Normally, strong currents of air called ‘trade winds’ blow from east to west over the Pacific. Matching ocean currents push the warmest water at the ocean’s surface from South America toward Australia and Southeast Asia During El Niño, though, the trade winds get much weaker, air pressure over the Pacific decreases, and warm water starts flowing east instead.
Why El Niño matters
The surface temperature of water in different regions of the Pacific causes dramatic changes in weather and other conditions. This can affect human activities, like fishing and farming, and can even threaten human lives. For example, the warm water near South America during El Niño means more moisture evaporates into the air, which means more cloud formation and more rain in Ecuador and northern Peru. This rain is often severe enough to cause flooding and erosion on the coastline.
Meanwhile, Indonesia and Australia, where that rain would normally fall, experience droughts. If the drought is severe enough, it can interfere with farms growing food in these areas.
At the same time, the warm surface water near the South American coast interferes with fishing, since fish thrive in the colder, nutrient-rich water that usually rises from the bottom there. An upwelling of warmer water reduces the phytoplankton that means less food for fish.
A press release on the 25th updated the current situation. A rapid, recent heating of the world’s oceans has alarmed scientists concerned that it will add to global warming. In April, the global sea surface hit a new record high temperature. “It has never warmed this much, this quickly,” they state.
Planet Earth continues to run a fever. Data released by the Copernicus Climate Change Service last week showed that March of 2023 was the planet’s second-warmest month in recorded history, registering average global temperatures 0.92 degrees Fahrenheit above normal high temperatures measured between 1991 and 2020. On Thursday, the National Oceanic and Atmospheric Administration (NOAA) confirmed the March findings, adding that “Polar sea ice saw its second-smallest March coverage on record. The warmest March on record occurred in 2016 when an El Niño weather pattern helped shatter heat records around the globe.
www.windrushweather.co.uk