IEM Daily Feature
Wednesday, 28 March 2018

Tornado Warning Polygons

Posted: 28 Mar 2018 05:33 AM

This is Severe Weather Awareness Week in Iowa and Wednesday's topic is tornadoes. Tornadoes have been recorded in Iowa during each month of the year and about every hour of the day. The NWS issues Tornado Warning "Storm Based Warnings" in the form of geographic polygons. While the featured map may look like your grandmother's quilt, it is actually a map showing the last year a location in the state was under a Tornado Warning. The archive for these polygons goes back to 2002, but they were not the operational warning until late 2007. There are a number of interesting artifacts on the map including some slivers of the state that have not seen a polygon Tornado Warning since at least 2002. You can generate maps like these on this website for other states along with many other options too!

Good = 15
Bad = 1

Tags:   swaw   nws   tornado