Exact dates 'tropical' heatwave hits North Wales with more hot weather to come

Wales Online

4 days ago

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Met Office weather maps show a heatwave is likely be declared in Wales over the coming days. The influence of a tropical storm is set to push temperatures close to 30C at the start of next week.
Already, a yellow heat health has been issued in England from Monday, August 11. According to the UK Health Security Agency, temperatures in the country are widely expected to rise above 30C, while the Met Office said there is a 'a 10% chance' the mercury could hit 34C in southern areas.
In Wales, the national forecaster expects Tuesday to be the warmest of the week, with northeastern areas set for highs of 27C-28C. Some models suggest temperatures here may even reach 32C, though this is unlikely. In northwest Wales, temperatures of 25C are expected widely, perhaps falling to 23C in north Anglesey.
There's a little uncertainty over the duration of the hot spell. However the Met Office is currently forecasting temperatures from Monday to Wednesday that would reach or exceed the three-day 25C benchmark for declaring a heatwave in Wales.
The expected arrival of the remnants of Tropical Storm Dexter has complicated forecasts - a few days ago they were predicting heat later in the week.
Regardless, the presence of high pressure, ridging from the Atlantic to Scandinavia, is set to maintain warm and pleasant conditions for the rest of the week. Sign up now for the latest news on the North Wales Live Whatsapp community
Some weather models even indicate a repeat the following week, with another three-day heatwave from Wednesday to Friday, August 20-22, giving peak temperatures of 29C in northeast Wales. However not all models are in agreement, with some suggesting a brief heat incursion only in southeast England.
(Image: Met Office)
(Image: Met Office)
(Image: Met Office)
Tropical storm uncertainty
According to the Met Office, Tropical Storm Dexter is expected to bring wet and windy conditions to northwest Britain. This is unlikely to be as severe as Storm Floris, which caused widespread travel disruption and power outages.
Further south, the storm will draw warm air up across the UK on Sunday (August 10) and into Monday. However there is still some uncertainty over its line of approach.
The Met Office said: 'Regardless of the exact track, many models suggest a warm plume of air will move in from the Atlantic, helping to boost temperatures from Sunday through to Wednesday. Box and whisker plots show increasing spread in temperature forecasts, indicating growing uncertainty but also a clear signal of rising heat.
'On Tuesday, the probability of reaching 30C increases, with some areas potentially climbing even higher. Wednesday may also bring similar conditions, though the longevity of any warmth is as yet very uncertain.'
Towards the end of the hot spell there is a chance of scattered thundery downpours developing in places. However these are expected to be few and far between.
The Met Office definition of a heatwave is three consecutive days of temperatures exceeding the 'heatwave threshold' for that part of the country. For most of the UK, this is 25C, with slightly higher numbers for the South and East, and rising to 28C in London.
Met Office deputy chief meteorologist, Steven Keates, said there was a chance the heat could linger in southeast England. He said: 'We're confident that temperatures will increase markedly by the start of next week, reaching the low 30s Celsius in parts of England on Monday and perhaps the mid 30s in a few places on Tuesday.
'However, the length of this warm spell is still uncertain, and it is possible that high temperatures could persist further into next week, particularly in the south.'
'Ex-Dexter sets the wheels in motion for an uptick in temperatures, but the weather patterns then maintaining any hot weather are rather more uncertain.' Sign up for the North Wales Live newsletter sent twice daily to your inbox
(Image: WXCharts)
Staying warm?
Current expectations are that fresher conditions could return late next weekend – though another hot spell could materialise later the following week.
It means there's not much rain in the medium-term forecast for southern Britain: the Met Office expects "a lot of dry weather to be had in the south under the influence of high pressure". Northwest UK may remain more unsettled with a "more changeable and breezier theme".
Longer term, the largely settled picture is predicted to remain in southern Britain for the rest of August. In its forecast for Saturday, August 23, to Saturday, September 6, the Met Office said: 'High pressure, and therefore largely settled conditions overall, appears more likely at first.
'Although dry weather is likely to dominate, periods of rain or showers and thunderstorms may develop at times. Above average temperatures overall seem most likely, with the potential for further hot spells to develop, especially in the east and south.
'By the turn of the month, there are signals for high pressure to become less dominant with perhaps a greater chance of some rain, though there is some uncertainty in this aspect of the forecast.'
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