Meteorology · Thunderstorms — Gust Front
The leading edge of cold downdraft air spreading out ahead of a thunderstorm is called the gust front. Mariners should expect:
- ARising temperature and clearing
- BA long period of calm before the storm
- CSteady backing winds over several hours
- DA sudden wind shift and strong squally gusts, often with a sharp temperature drop, just before the heaviest rain✓ Correct
Explanation
The cold downdraft outflow forms a gust front (sometimes marked by a roll/shelf cloud) that arrives ahead of the rain, bringing an abrupt wind shift, strong gusts, and a temperature drop — a hazard for small craft and for vessels carrying sail.
Authority: Bowditch (Pub. No. 9), thunderstorms and squalls; WMO
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