It’s not surprising that the high cloud has spread south so rapidly in the last few hours as there was a 150 knot northerly jet at midnight down across the country.
I don’t know the exact technical term for this ‘shield’ of cloud is, other than calling it jet stream cirrus but I know its a harbinger of rapid development. I quite like shield of cloud that I’ve coined, who knows perhaps it’ll catch on.
Another daft idea that may well come to nothing.
In the shape of an upper cold pool off the Brest peninsula maybe.
Can these observation from Cairnwell be believed?
November 10 visible satellite image
The jetstream in action