This storm has been strengthening significantly over the last hour.

…SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN MARSHALL…NORTHERN TAMA…SOUTHEASTERN HARDIN…SOUTHERN GRUNDY AND SOUTHWESTERN BLACK HAWK COUNTIES UNTIL 1030 PM CDT…

AT 1003 PM CDT…NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR GRUNDY CENTER…OR 28 MILES SOUTHWEST OF WATERLOO…MOVING EAST AT 35 MPH.

PENNY SIZE HAIL…AND WINDS IN EXCESS OF 45 MPH ARE EXPECTED WITH THIS STORM.