Hail size 1"
Grinnell Poweshiek County
“Time and location estimated from radar. (DMX)”
— NOAA / SPC storm report
/ Storm field report · Jasper
Hail in Grinnell · Apr 17, 2026
NEXRAD logged 24 hail signatures up to 2.5"; the estimated-size surface reached 1.5" aloft. At 2.5" — baseball — this is a severe hail signal associated with roof damage. Open it on the live map to see the swath over the streets.
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Peak hail signal 2.5" ≈ baseball · the largest NEXRAD radar signature
Homes in the hail footprint 732
Ground reports 2 2 hail
Radar surfaces 2 NEXRAD + estimated size
Convective day · Apr 17, 2026 · noon–noon UTC
Severity
The most severe storm Grinnell has seen in the last 12 months
Composite score · 5.7 / 10
Storm severity score
Overview's storm severity score weighs hailstone size, homes in the footprint, and ground-truth reports.
5.7 /10
- Peak hail signal
- 63 /100
- Homes exposed
- 57 /100
- Ground truth
- 33 /100
Largest radar-indicated size — a signal of damage potential, not confirmation.
How many homes sit inside the storm's footprint.
Independent storm reports filed with the NWS.
Evidence / storm surfaces
How Grinnell saw the hail — from two instruments
Apr 17, 2026 · Grinnell, IA
The maps here read the same storm from two angles — point detections from NEXRAD, and modeled hail size aloft. Where the two disagree is informative: it marks where estimated size outran the signatures, or trailed them.
NEXRAD radar signatures Surface resolved
Radar signature field Where NEXRAD flagged hail as the storm passed — point signatures from the radar, which indicate hail overhead rather than confirm what landed.
Max size
2.5"
Detections
24
Radar-estimated hail size Surface resolved
Estimated size field The modeled maximum hail size across the swath, derived from radar aloft — the largest stone the storm could have supported, which is not necessarily what reached the ground.
Max size
1.5"
The storm in context
Where Apr 17, 2026 sits in Grinnell's hail record.
This was Grinnell's 4th recorded hail day, arriving 2 days after the Apr 15, 2026 storm. By severity it ranks 1st of the 9 storms we have logged here. Radar put the day's largest stone over Grinnell at 2.5" — the largest NEXRAD radar signature.
The Apr 17, 2026 convective day was bigger than Grinnell: the same system put hail over 1,016 other tracked cities, 201 of them in Iowa. Nearest: Kellogg (5 miles west, up to 2.5"); Lynnville (7 miles south, up to 1.5"); Sully (9 miles southwest, up to 1.75").
These maps are stills. In the app this date is one of 9 Grinnell storm dates on a live map — both surfaces, the reports, and a replay — and the same map is where you draw the swath. This page rebuilds nightly.
Ground reports
What people on the ground reported
2 reports filed with the NWS
These are storm reports filed with the National Weather Service and released through the NOAA Storm Prediction Center — public-domain observations from spotters, the public, and NWS surveys. We quote each one exactly as filed.
Hail reports
2 reports Hail size 1"
3 NE Oakland Acres Jasper County
“Delayed report - time estimated from radar. (DMX)”
— NOAA / SPC storm report
Storm forensics
How the storm moved
Timing and place names from NOAA ground reports
Read from the arrival times and locations of the NOAA ground reports, not a radar-measured storm track.
Hail was reported over 15 minutes, from to .
Reports came from Oakland Acres — beyond Grinnell itself.
Severe hail signal
What 2.5" hail means for Grinnell roofs.
Two-inch-plus hail is capable of puncturing shingles, breaking skylights or windows, and heavily denting soft materials. The strongest radar bands warrant prompt inspection, but neither the signal nor the footprint confirms damage at a specific address.
Radar reading · not confirmed damage
Roofing exposure
What this storm is worth to a roofer.
732 homes × $12,000 avg. claim
Potential roof exposure
$8.8M
Potential roof exposure — 732 homes × the ~$12,000 industry-average hail roof claim. Exposure, not confirmed damage.
- Illustrative jobs
- 4 jobs
- Illustrative work
- ~$60K
Close just 0.5% of the 732 homes in this footprint at the average $15,000 roof job. Illustrative math, not a projection — your results depend on your outreach and how the market responds.
Claim window
April 2028
Claims from this storm can typically be filed until around April 2028 — the window to reach these homeowners while it's still open. Deadlines vary by policy and state.
Names and phones for every home in the footprint: at most $154 on top of the $150 plan.
Grinnell hail history
Other storms in Grinnell.
9 recorded storm days in Grinnell, IA
Estimated-size surface Storm date Grinnell / IA
Aug 10, 2026
0.75" Estimated 0.75"
No ground reports filed Open report →
Estimated-size surface Storm date Grinnell / IA
Jul 20, 2026
0.5" Estimated 0.5"
No ground reports filed Open report →
Estimated-size surface Storm date Grinnell / IA
Jul 3, 2026
1" Signatures 1" Estimated 0.5"
No ground reports filed Open report →
Estimated-size surface Storm date Grinnell / IA
Jun 16, 2026
0.5" Estimated 0.5"
No ground reports filed Open report →
Estimated-size surface Storm date Grinnell / IA
May 15, 2026
1" Signatures 1" Estimated 0.5"
No ground reports filed Open report →
Estimated-size surface Storm date Grinnell / IA
Apr 15, 2026
0.5" Estimated 0.5"
No ground reports filed Open report →
Estimated-size surface Storm date Grinnell / IA
Apr 14, 2026
0.75" Estimated 0.75"
1 ground report Open report →
Estimated-size surface Storm date Grinnell / IA
Mar 30, 2026
No ground reports filed Open report →
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Set your territory and alerts today. When hail hits, use Overview to choose your streets and get moving.
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A storm day here is a convective day — it runs from noon to noon
UTC, so late-night hail is grouped with the afternoon storm that
spawned it rather than split across two calendar dates. Ground
reports are public-domain observations from the NOAA Storm
Prediction Center. Radar tells you where to look. Only an inspection confirms damage at an address. Last updated Aug 11, 2026.