Strange Penzance forecast.

[Graham Easterling]

Unbroken sunshine today, not a cloud in the sky (currently 12:05)

There was a dark cloud forecast for Penzance at noon. Current forecat

Reality - now 12:05 Marazion looking right across Mount's Bay towards Penzance /Newlyn.

Temperature only a bit above forecast levels, despite the unbroken sunshine, currently around 15.5C.  

Convergence of the easterly wind off Cape Cornwall has produced the typical line of cloud, you'd need to be very unlucky to be under it. I can only assume the model expected the convergence to be in a different postion.

Graham

Penzance

[Freddie]

There's some additional dynamic uplift making its way SSW that is forecast to join forces with the convergence.  I think the timing's a bit out as the forcing has only just (1300 BST) moved off the coast of south Wales.  So probably more cloudy later this afternoon than with typical convergence, and maybe some showers too.

[Graham Easterling]

Yes, certainly the onset of the north coast sea breeze initiated the line of cumuliform cloud. THe roll of cloud gradually moved south to reach the south coast by about 2pm. This southward movement is common, probably the greater heating of the NW facing north coast in the afternoon plays a part.

By 3pmish the north coast sea breeze limit was just south of Penzance.

The sea breeze front ust south of Newlyn Green (my photo, looking SSE) Still cloudless in the distance.

The temperature peaked at 16.7C in the sunshine as the wind dropped away, just the cloud was directly overhead There was then a light NNE breeze, so typical sequence as the sea breeze front past overhead. However, instead of being followed by deep blue sky there was a lot of thin semi transparent Ac, with a few thicker patches with embedded small Cu. So, as you say. there was more going on. Endlessly intersting the weather.

A rather more impressive sea breeze front marching south, taken from virtually the same location. This time accompanied by a brief sharp shower and followed by the more typical deep blue sky.

Graham

Penzance