There's been a heat low over south Wales over the past couple of afternoons and evenings. In fact, it has been occurring quite often in the past month. It's tricky to pick out as there aren't any official observations inland between Cardiff on the coast and Sennybridge and Shobdon/Hereford to the north. If you look at other sources (WOW, Wunderground) you can easily make out the relatively lower pressure. Also, observation of wind direction at my location is very revealing - with some quite marked reversals during the day. You can also pick out low level convergence by studying animations of visible satellite imagery,

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Freddie
Ystrad
Rhondda
148m AMSL
http://www.hosiene.co.uk/weather/
https://twitter.com/YstradRhonddaWx for hourly reports (no wind measurement currently)

The large number of AWS make it easier to prove local circulations always previously suspected.

There's a very distinct daily sea breeze pattern here, particularly under a strong 'Azores' ridge over SW England. The recent ridging has been rather too far north for the pattern to be clear - to much of a gradient E-NE wind..

The strong morning heating of the south coast quickly starts a sea breeze into Mount's Bay, always particularly strong at Marazion where there are no hills behind to impede the flow. It often results in an offshore SE between Lands End & Sennen, flowing up the valley behind Porthcurno and down Vallendreath at Sennen.

During the early afternoon the strong heating of the generally NW facing 'north' coast results quite a strong sea breeze in St Ives Bay which funnels through Hayle Saltings to Marazion marsh. At Marazion it can cause a complete reversal of the wind direction mid afternoon. The progress often marked by the normal sea breeze limit line of cloud.

The net result of all this is a circular wind flow around the Lands end peninsula. Something I always suspected, but now with my own station, the AWS at Gwennap Head (John's Lands End site), Lands End airport (near St Just) Bosullow (centre of the peninsula) & St Ives as well as Camborne, the evidence is there.

Patchy thin Sc this morning, and only 19C @ 09:00. Much more pleasant.

Graham
Penzance