The horizontal distance an observer can see and identify a prominent object. A boundary between a warm airmass that is replacing a cooler airmass. The level of a river or stream which may cause minor flooding, and at which concerned interests should take action. Take a look at a sample warning issued by the National Weather Service. Take a look at a sample watch issued by the National Weather Service.
Issuance is normally site specific.
However, winds of this magnitude occurring over an area that frequently experiences such winds would not require the issuance of this advisory. The change of wind speed or direction with distance, usually vertical. An instrument that determines the direction from which a wind is blowing. Wind Chill Chart View an informative QuickTime animation on the wind chill factor . A heavy snow event.