Blowing spray
From Glossary of Meteorology
blowing spray
Water droplets displaced by the wind from a body of water, generally from the crests of waves, and carried up into the air in such quantities that they reduce the horizontal visibility to less than 11 km (about 7 statute miles).
It is encoded as BY as an obstruction to vision in surface aviation weather observation and as BLPY as an obstruction to vision in a METAR or SPECI observation.