Gail Force Online

34–40 knots. Moderately high waves of greater length; edges of crests break into spindrift.

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

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 34–40 knots