34–40 knots. Moderately high waves of greater length; edges of crests break into spindrift.
48–55 knots. Very high waves with long overhanging crests; the sea surface takes on a white appearance. Safety and Preparation Guide gail force
28–33 knots. Sea heaps up and white foam from breaking waves begins to be blown in streaks. 34–40 knots
"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 Very high waves with long overhanging crests; the
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