How Likely Is a Tornado in Harrison County, IA?
Harrison County's tornado history, by the numbers
Harrison County has recorded 33 tornado touches in NOAA's 76-year database, a rate of roughly one every 2.3 years - our Elevated band. Put another way: Harrison County sees more tornado activity than 72% of US counties. Among 99 Iowa counties in this dataset, Harrison County ranks 52 for how often a tornado touches down.
Beyond the frequency band: violent history
20 weak and 12 significant tornadoes make up Harrison County's 33-track record - none violent. NOAA has never logged an EF4 or EF5 crossing this county.
The dollar figure Harrison County's rating leads to
Cost nationally: $2,890-$13,280, about $7,645 typical. Iowa has no state rebate program confirmed here; FEMA's underlying 75% cost-share exists nationwide, but applying through a state program is what usually makes it real, and none was found for Iowa this pass.
What a direct hit isn't required for
A direct hit is not required for Harrison County to lose power - outbreak-wide outages across Iowa regularly reach homes and businesses well outside the actual tracks. A battery bank covers that gap without a generator's fuel and venting needs.
What this number is, and is not
One caveat before relying on Harrison County's number: it is county-wide, and it covers about 697 square miles, so a single touch counts the same as one in a county a fraction of that size. Weaker pre-1990s tornadoes are also documented as undercounted in NOAA's own record. Harrison County has about 14,626 residents.