Friday 29th May
Thursday was the last day under heatwave conditions with a maximum of 28.8C at 15.33, being 11.5C above average. The heatwave lasted for five days with maximum temperatures equal to or above 27C for Wiltshire. The past night was also much cooler that saw the thermometer drop away to a low of 13.1C at 03.42 early Friday, being 6.1C above average.
The soil temperature at a depth of 5cm, read at 08.00 every morning, has seen the gradual decline in the heat with temperatures of 24.0C, 23.3C, 23.1C and 20.4C respectively, over the last four days.
The back track of the weather radar this morning showed a narrow band of thicker cloud passing over our area in the early hours that deposited just a few drops of rain around 05.30, not even a shower, observed on horizontal surfaces just after 06.00.
Friday arrived with quite a contrast in weather to recent days with no strong sunshine after sunrise but cloudy conditions, which is the result of cloud associated with a weather front crossing the area during the morning bringing cooler air behind it. There will be sone brightness, but no continuous strong sunshine, which will be quite a relief after the extreme temperatures brought by the heatwave over the last five days.
The recent dominant anticyclone has relinquished its grip, sliding away back to the Azores region, but leaving a modest ridge of higher pressure over the UK that will fend off the advance of depressions from the Atlantic for the next few days. However, A distinct change in our weather will be arrive from Sunday that will see the wind come from a westerly quarter for a few days heralding the arrival of Atlantic air that will be cooler and more moist, with possible light rain, quantities uncertain at the moment.
There have been a number of comments in the news recently about a major meteorological phenomenon, which will have a major impact over the Americas although is likely to influence our weather in the future. I attach recent news items with comments from the Met Office and other meteorologists.
Super El Nino: If you think it’s hot now, time to brace for what is coming next
After May’s soaring temperatures, experts warn this heatwave could be just the beginning. Scientists report why they fear one of the most powerful weather events ever seen could be soon heading our way
There’s definitely something coming. We’re very confident about that, and it looks like it will be a big event.”
Adam Scaife, head of long-range prediction at the UK Met Office, recently gave this somewhat ominous proclamation. He was talking about the potential approaching El Nino – possibly so strong it may be classified as a “Super El Nino” – and warned it could “even be of record strength”.
The El Nino effect is a natural, cyclical climate pattern in the Pacific Ocean, characterised by the warming of surface ocean temperatures in the central and eastern equatorial Pacific.
Under normal conditions, trade winds blow westward along the equator, pushing warm water from South America towards Asia; cold water rises from below to replace this warmer water in a process known as upwelling. But El Nino throws all that into disarray. Trade winds aren’t as strong, and so the warm waters head east towards the Americas instead, forcing the Pacific jet stream south of its neutral position.
Upwelling weakens or stops altogether; without the nutrients being transported from the depths to the shallows of the ocean, there are fewer phytoplankton off the coast, which in turn impacts fish that eat phytoplankton, which in turn impacts everything that eats fish.
Entire ecosystems are disrupted by the change.
In the UK specifically, the El Nino effect is usually weaker but can lead to more dramatic weather extremes: winter temperatures tend to be colder, especially later in the season, while in summer the mercury soars. This current heatwave might prove the tip of the iceberg.
“Summer temperatures could certainly be impacted, possibly this year, but more likely next, as the planet heats up,” says Professor Bill McGuire, emeritus professor of geophysical and climate hazards at University College London and author of the new book The Fate of the World: A History and Future of the Climate Crisis. “I wouldn’t be at all surprised to see 40C-plus heat.”
What tips an El Nino into “super” territory is all to do with water temperature. “If sea surface temperatures there are more than 0.5C above normal for the time of year, we say that those are El Nino conditions,” according to Mark Roulston, senior research fellow and director of operations for Lancaster University’s Climate Risk and Uncertainty Collective Intelligence Aggregation Laboratory (Crucial).
“A ‘Super El Nino’ is often defined as when these temperatures are more than 2C above normal for the time of year, so a more extreme version of the El Nino phenomenon.”