Severe weather struck the US north-east last Thursday, with thunderstorms and tornadoes causing damage and disruption. A tornado hit Dover, Delaware, and another was reported near Atlantic Beach on Long Island, New York.
The Long Island tornado was rated EF-1 by the National Weather Service, with peak winds of 97mph (156kph). It was the first tornado reported in Nassau County since November 2021. Buildings and beach cabanas were damaged, and heavy rainfall led to flash flooding and power cuts.
UK weather turns cooler with thundery rain
In the UK, after a summer of high temperatures and little meaningful rainfall, conditions have turned cooler in recent days with heavy showers and thunderstorms. High pressure brought a mainly dry and settled weekend, but more unsettled weather is expected from Tuesday. Showers, thunderstorms and longer spells of thundery rain are forecast to spread northwards, with temperatures increasing as warmer southerly winds develop.
Powerful El Niño developing in the Pacific
According to the UK Met Office, a powerful El Niño is developing in the Pacific Ocean and could be the strongest in living memory. El Niño is a naturally occurring climate pattern that occurs every two to seven years. It can trigger major shifts in global weather, leading to drought, flooding and wildfires, but no two events are the same and impacts can differ. Effects are greatest in the tropics. India has already seen weaker than average monsoon rainfall, while Atlantic hurricane activity has been suppressed.
Trade winds that usually move east to west across the Pacific can weaken or reverse, allowing warm water to push eastwards. Sea surface temperatures in the region are forecast to climb by more than 3C above average later this year, which would make it the strongest El Niño since records began in 1950. Some forecasts suggest it could reach an unprecedented 4C above average. Global temperatures rise due to heat transfer from ocean to atmosphere, and this year’s El Niño means 2027 is likely to be the warmest year ever recorded globally.
Potential impacts for the UK
For the UK, El Niño increases the risk of a wet and stormy autumn and can increase the risk of colder weather later in winter across north-west Europe. Some longer-range forecast models already show signs that this autumn and early winter could be wetter than normal. In a warming world, El Niño impacts are likely to be more severe, but there is currently no strong evidence that climate change is making these events more likely.
