A screen temp of -3 becomes moderate with wind of only 2 knots, severe with
9 knots and very severe with wind greater than 14 knots. Terms such as
'penetrating' etc can be used if forecaster deems it appropriate.
Source FRB 1993
Incidentally in Calm conditions 3.5 is moderate, 6.5 is severe and 11.5
very severe.
Terminology may have changed over the years...
Cheers
John
(ps moon still visible here but getting ever hazier)
--
York,
North Yorkshire.
(Norman Virus Protected)