The start-time of a warning area surely has to be the earliest time of onset of the hazard and later today (soon!) you will be having the same area of snow. Suppose it could be sleet on the coast. The Torquay area and places inland have had atrocious snow over the last few hours. The Minack theatre webcam is showing darker skies heading in from the east - good view.

Julian

Molesey, Surrey