WECA - Weather GlossaryNational Weather Service Upton, NY November 1, 1995 Terminologies: Winter & Fall Blizzard Warning - Issued for winter storm with sustained or frequent winds of 35 mph or higher with considerable falling and/or blowing snow that frequently reduces visibility to 1/4 of a mile or less. Blowing Snow Advisory - Issued when wind driven snow reduces surface visibility, possibly, hampering traveling. Drifting Snow - An uneven distribution of snowfall or existing snow caused by strong surface wind. Freeze - A condition occurring over a large area when the surface air temperature remains below 32 degrees Fahrenheit for an extended period of time possibly leading to the damage of certain crops. Freeze Warning - Issued during the growing season when surface temperatures are expected to drop below freezing over a large area for an extended period of time, regardless if frost develops or not. Frost - A covering of ice on exposed surfaces when the air temperature falls below the frost point.