Tornadoes and 'marble-sized hail' an outside chance in stormy weekend weather forecast
Forecasters are expecting an “interesting” weekend of weather as troughs and fronts gather over the UK. Two yellow warning for thunderstorms have been issued for Wales already and the Met Office said hail is a possibility too.
One online forecaster has gone further, saying conditions could be right for “isolated tornadoes” to develop. On X ( Twitter ), Skies Of The UK said funnel clouds are more likely but heavy falls of hail may happen and these could be “1-2cm long and wide”. Funnel clouds are spinning columns of cloud that, unlike tornadoes, don’t reach the ground.
The Met Office today issued two yellow alerts for thunderstorms. The first is from 12pm-8pm on Friday, September 20, and covers southern England and South Wales up as far as Montgomery, Powys. The second is on Saturday, September 21, from 1am to midnight - this one covers the whole of Wales.
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Met Office chief meteorologist Neil Armstrong, said: “Thundery downpours are expected to develop in places across the south on Friday afternoon bringing frequent lightning, gusty winds, hail, and spells of heavy rain. The risk of thunderstorms persists into Saturday with potentially longer spells of heavy rain for some along with a continued risk of hail and lightning accompanying the most intense storms, particularly in parts of the Midlands, southern England and east Wales during Saturday afternoon and evening.
“The warnings cover the areas of the country most at risk of seeing thunderstorms. But not everyone within a warning area will experience a thunderstorm. For many much of the time it will remain dry.”
While not all places will see thunderstorms, where they do occur 20mm-40 mm of rain could fall in less than an hour. In a few isolated spots, there’s a small chance of 50mm-70mm falling over hours, said the Met Office. Sign up now for the latest news on the North Wales Live Whatsapp community
Prompting the stormy weather is a block of low-pressure system building into the high pressure that’s hung over the UK in recent days. This is set to spark two or three days of convection, creating instability in the atmosphere. In certain conditions it can lead to tornados but in the UK these are relatively rare: on average there are around 30 each year.
Some weather models suggest more storms over North Wales on Sunday evening and the Met Office has not ruled out further alerts. Mr Armstrong said: “We are expecting showers to merge into longer spells of heavy rain on Sunday and Monday across some southern and central parts. Once the full details become clearer, we may well issue further severe weather warnings.
“This change to more unsettled weather will also see a downturn in temperatures, particularly as we go into next week. We are expecting a window of drier conditions for most places on Tuesday before wet and windy, ‘autumnal’, weather once again moves across the UK from the North Atlantic.” Sign up for the North Wales Live newsletter sent twice daily to your inbox
For its local weekend forecast for Valley, Anglesey, the Met Office reached for the songbook to take a more relaxed approach to the coming storms. Earlier today it wrote on X (Twitter)....
“You are my sunshine, my Valley sunshine. Make me happy, for some more days.
You may not know now, that showers are coming. But the weekend’s a long way away.”
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