A storm has movement that is often referenced in the direction it is moving and the speed it is moving. For example, a severe thunderstorm near city A is moving toward the northeast at 25 miles per hour. When looking at radar, this information can be used to see which cities are in the potential path of the storm. The display will show an expanding cone shape away from the storm in the direction the storm is moving since uncertainty increases the further away from the storm a location is. Cities and locations in the immediate vicinity of the path will be warned when a severe thunderstorm is moving toward the cities. A storm must be thought of as a process and not an object that moves from point A to point B. The processes involved with a storm include vertical expansion through updrafts, downdrafts originating from the storm, newer storms potentially forming near the storm and interacting with it, multiple updrafts in the storm interacting with each other, the storm developing/maturing/then dissipating, moving into an environment more conducive or less conducive to development, turbulence within the storm, etc. Thus, the storm characteristics at Point A can change as it moves to Point B, for better or worse. Each severe storm requires close monitoring. The development of new storms must be closely monitored also since a storm can go from just developing to severe in a matter of minutes. A severe storm can also washout and dissipate quickly if it moves into an environment less conducive to storm updrafts or when the downdrafts dominate over the updrafts of the storm. A particular storm will sometimes be referenced to having a certain history, such as “this storm has a history of producing large hail”. If this is a storm that can maintain its characteristics over time (supercell character, staying in environment conducive to strong storms), then it can be expected the storm will produce the same type of severe weather as it moves and develops. Common histories of a storm to watch out for are high convective wind gusts, damaging hail, flashing flooding rain, and tornadoes. A storm may have all these characteristics or just select ones. A meteorologist forecasts the potential characteristics storms will have in order to prepare the public for the potential risk. When the event hits, frequent updates will be given on the severe weather threat from the storms that have developed. |