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Alex95

Sea Breeze Thunderstorms In The Uk?

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Does anyone know of any instances in the UK where sea breeze initiated storms have occurred? They occur almost daily during the wet season in Florida where the two sea breezes from the Atlantic and the Gulf of Mexico converge in the middle of the state bringing spectacular thunderstorms. Polk County gets around 25 storms a month in June, July and August. Further convergence areas are then set up by thunderstorm outflows, allowing the storms to rumble on into the night even after the sea breeze dies out. A similar effect occurs in Cuba where the sea breeze from the north meets the sea breeze from the south, although it is less pronounced than in Florida. I also believe it can occur in Italy from time to time. As the UK is also quite narrow I wonder if its possible for a westerly sea breeze to meet an easterly sea breeze to bring thunderstorms? In Florida it usually only occurs from May to September as the sea surface temperatures are in the low 30s, and the temperatures over land need to be higher than this for a sea breeze to set up, but the seas around the UK are far cooler, so sea breezes can more easily affect the UK. If anyone knows of an example of a sea breeze thunderstorm outbreak in the UK I'd very grateful if they could let me know when it happened!

I have attached a diagram I found which outlines the phenomenon quite well:

post-9381-0-96184200-1329055301_thumb.jp

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I can't think of a specific example but in Cornwall you get what is known as the A30 convergence zone where roughly the sea beeze from the north coast meets the sea breeze from the south coast. You can get quite strong convective activity along this line but very hot weather is not that common in Cornwall. Whether this convection is strong enough to generate thunderstorms I'm not sure but it's a possibility.

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I can't think of a specific example but in Cornwall you get what is known as the A30 convergence zone where roughly the sea beeze from the north coast meets the sea breeze from the south coast. You can get quite strong convective activity along this line but very hot weather is not that common in Cornwall. Whether this convection is strong enough to generate thunderstorms I'm not sure but it's a possibility.

Ah, is this what caused the Boscastle flood in 2004? I notice on Wikipedia they say it's known locally as the 'brown willy effect', named after the highest point in Cornwall. I find this phenomenon fascinating as the storms produced can bring exceptionally intense rain and lightning, but they rarely turn into supercells.

http://en.wikipedia.org/wiki/Brown_Willy_effect

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Ah, is this what caused the Boscastle flood in 2004? I notice on Wikipedia they say it's known locally as the 'brown willy effect', named after the highest point in Cornwall. I find this phenomenon fascinating as the storms produced can bring exceptionally intense rain and lightning, but they rarely turn into supercells.

http://en.wikipedia....wn_Willy_effect

No that was quite different. I would treat the Wiki account with some caution. If you are really interested in the Boscastle event the RMetS did a special issue on it in August 2005, vol 60, No.8.

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Cornwall is much narrower than Florida; northern England is a bit closer in dimensions and does occasionally get convergence thunderstorms though the hilly topography also has an influence whereas Florida is flat.

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No that was quite different. I would treat the Wiki account with some caution. If you are really interested in the Boscastle event the RMetS did a special issue on it in August 2005, vol 60, No.8.

OK I'll have a look. I know Wiki can be a bit dodgy!

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OK I'll have a look. I know Wiki can be a bit dodgy!

I've put the links to the Boscastle event in the relevant thread in the history section.

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In the SW it isn't too unusual to get a line of convective showers running SW-NE up the middle of the peninsula, whether these are from two sea breezes meeting or in a general SW'erly flow due to the shape of the peninsula, though there may often be some backing of the winds over the land, I have a funny feeling this can contribute to events like Boscastle as well with a more SSW warmer wind of the land reaching a SW or WSW wind near the coast, though I may well be wrong there.

Sometimes the showers can produce thunder/lightning which technically makes them thunderstorms, so I suppose this is one case in the UK.

Last April on the 23rd cumulus clouds were bubbling around much of the morning with temps of 24C inland, and there was a sea breeze here with it being clear overhead and to the south. Eventually as the clearer skies pushed inland a little the cumulus closest to the clear sky towered into towering cumulus then CB cells that started giving off distant rumbles of thunder, the thunder was relatively frequent for a time with localized downpours north of here.

I don't think these were two sea breezes meeting, just the convergence from one sea breeze pushing inland, thought the wind did turn westerly/NW'erly here later in the afternoon/evening so it could have been.

I would guess most areas near the coast can have this with convection forming on the sea breeze boundary, and probably with two sea breezes meeting in places, but of course not to the extent that Florida does.

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