– The horizontal distance an observer can see and identify a prominent object.

A measure of the amount of “spin” (rotation) and “shear” in the atmosphere.

– Warm Air Advection

– An isolated lowering of a cloud that is attached to the rain-free base of a thunderstorm, generally to the rear of the visible precipitation area. Wall clouds indicate the updraft of or the inflow to a thunderstorm.

– A boundary between a warm airmass that is replacing a cooler airmass.

– is issued when severe or hazardous weather has already developed and has been reported by spotters or indicated by radar. Warnings are statements of imminent danger and are issued for relatively small areas near and downstream from the severe storm or flood. For example, Tornado Warning, Severe Thunderstorm Warning, Flash Flood Warning, Winter Storm Warning.

– identifies a relatively large area in which hazardous or severe weather might occur. The watch is only an indication of where and when the severe weather probabilities are the highest, and should not be confused with a warning. Examples include Tornado Watch, Severe Thunderstorm Watch, Flash Flood Watch, Winter Storm Watch.