Gail Force -

41–47 knots. High waves; dense streaks of foam along the direction of the wind; sea begins to roll.

Gale force winds can cause structural damage to roofing and siding and create life-threatening conditions for mariners. Weather Spotter's Field Guide - Non-supercell Tornadoes gail force

48–55 knots. Very high waves with long overhanging crests; the sea surface takes on a white appearance. Safety and Preparation Guide 41–47 knots