Vince_Condella's Blog

I know the title of this blog must seem obvious, but many people are amazed that severe thunderstorm warnings are not issued more often.  The storms this morning (Monday, July 7) were a good example.  They were loud, the skies were dark, the winds were gusting, but only a small part of southeast Wisconsin was put under a severe thunderstorm warning.

A severe thunderstorm is defined as one that (1) has wind gusts 58 mph or higher and/or (2) produces hail 3/4" diameter (penny size) or greater.  Lightning can be fierce in a thunderstorm, and it can be deadly.  But lightning alone does not prompt a severe thunderstorm warning.  Winds can be gusty and knock over lawn furniture and even knock small branches off of trees, but if the wind gusts are below 58 mph it is not a severe thunderstorm.

Some meteorologists are lobbying to get the hail limit raised to 1" diameter (quarter size) or greater so fewer severe thunderstorm warnings will be issued.  The National Weather Service issues a warning based on what they observe from their Doppler radar and/or from storm spotter reports on the ground.  If a storm is showing a strengthening trend on radar and it appears as if the hail size in the core of the storm is growing, a severe thunderstorm warning will be issued.

This morning the storms were obnoxious and loud and they did some minor damage.  But only in a few areas did they exceed the severe weather limit.  Don't expect warnings for every storm, even those that may look really nasty.  But do be prepared for the dangers of gusty wind, lightning, and locally heavy rainfall with any thunderstorm.