Penzance - Torrential

[Graham Easterling]

Wow, for 7 or 8 minutes that was the heaviest rain for a long time. Short lived but absolutely torrential under line convection. Very sharp, sudden clearance to blue sky.  

. . and very sharp drop in wind strength.

Graham

Penzance

.

[Freddie]

Quite a marked cold front in terms of precipitation and wind behaviour.  Not so much, I guess, in terms of temperature and dewpoint change.

[Graham Easterling]

Yes, the temperature bare changed.

At Lands End - Wind direction

and strength

Graham

Penzance

[Len]

So how much rain did you get in that 7 or 8 mins Graham?

When the line went through here in Wembury we got 2 mm. 

Certainly very heavy rain but I am not sure I would call it torrential.

Len

[Graham Easterling]

I can't be exact Len.

I was actually driving back home through Penzance as it hit, and virtually all the cars, including me, briefly stopped as it was almost impossible to see. The last time I had to do that was a few years back in a good thunderstorm at Camborne.

I got home just as it was ending and checked the gauge which had 7.8mm. Prior to the cloudburst we'd only had fairly light & patchy rain since 09:00, I would guess 1-2mm. So I think 6 to 6.5mm in <10 minutes would be a reasonable estimate. Looking at the rainfall radar a very narrow E-W band formed west of Scilly and intensify significantly as it approached Penzance & then weakened again after. Trengwainton got less, but the narrow band seemed to wobble over Penzance. There was a torrential burst, then it eased slightly with blue sky clearly visible to the north, then another equally heavy burst.

All short lived but quite exciting at the time. I don't think I'll ever repeat the 90.2mm I recorded in 2 hours at Wootton Bassett many years ago. That was incredible, washed away garden walls etc. as the water got trapped behind. Most scary incident was being right under a thunderstorm on Striding Edge, Helvellyn back in 1965, I was a mere lad.

Graham

Penzance