The National Weather Service issues Special Weather Statements (abbreviated SPS) to typically cover storms that are slightly below severe thresholds (wind gusts below 57 MPH, hail below 1 inch diameter). Like thunderstorm warnings, these alerts can include a polygon region to delineate a sub-county area most under the specific threat. The featured chart presents an IEM accounting of the number of such SPS alerts containing a polygon (read: typically these are for convective storms) that intersects with Iowa. The values shown before 2009 were experiments and/or test usage of such polygons. Of note is the total of just 6 such alerts for May 2025. This correlates well with the daily feature last week denoting just 1 Tornado Warning for the month. The IEM offers a download portal for these polygons and also the raw issued product text.

Voting:
Good = 9
Bad = 0