Answer:
It varies somewhat depending on the type of storm. They look at a variety of conditions such as temperature, dew point, and upper-level winds. Storms form best when the air is warm and moist. They also look for possible triggers, such as an area of low pressure or a front (a boundary between warm and cold or moist and dry air masses). If a storm or storm system has already developed, then meteorologists will monitor wind currents that are along its track it in order to tell what areas it might hit. Beyond those basics, the factors analyzed will vary with the type of storm.