"Gale force" (often misspelled as "gail force") primarily refers to sustained surface winds between (39–54 mph). In meteorology, these conditions correspond to forces 7 through 10 on the Beaufort Wind Scale . Understanding Gale Force Classifications
28–33 knots. Sea heaps up and white foam from breaking waves begins to be blown in streaks. gail force
41–47 knots. High waves; dense streaks of foam along the direction of the wind; sea begins to roll. "Gale force" (often misspelled as "gail force") primarily
34–40 knots. Moderately high waves of greater length; edges of crests break into spindrift. Sea heaps up and white foam from breaking
Winds are categorized based on their intensity and the observed conditions they cause:
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
48–55 knots. Very high waves with long overhanging crests; the sea surface takes on a white appearance. Safety and Preparation Guide