– A violently rotating column of air usually forming a pendant from a cumulus/cumulonimbus cloud, occurring over a body of water, and having circulation reaching the water.

– water substance in a gaseous state that comprises one of the most important of all the constituents of the atmosphere.

– Weather Forecast Office. Designation of NWS operational offices after modernization.

– air in motion relative to the surface of the earth.

– Sustained winds 25 to 39 mph and/or gusts to 57 mph. Issuance is normally site specific. However, winds of this magnitude occurring over an area that frequently experiences such winds (e.g., the normal strong summertime winds near the San Francisco Bay, would not require the issuance of this product).

– The apparent temperature that describes the cooling effect on exposed skin by the combination of temperature and wind, expressed as a loss of body heat. An increase in wind speed or decrease in temperature will accelerate the effect. A wind chill factor of 30 degrees or lower on exposed skin will result in frostbite in a short period of time.

-The change of wind speed or direction with distance or height.