Jon O'Rourke wrote:

The gradient was expected to increase this evening over northern England
aiding wave generation and I'd image this is the primary cause for what
you've experienced again, Ken. SIGMETs have been running all day for severe
mountain waves for the Scottish Flight Information Region (FIR) and may now
be required for the north of the London FIR.

Thanks for that, Jon. Our local forecast this evening was going for
gusty winds.
Back to 23007KT at 2350Z after 27033G41KT an hour ago!
Looks like we're in for a roller coaster night.

Ken
Copley
http://copley.mysite.orange.co.uk