NEXRAD logged 22 hail signatures up to 2.75"; the estimated-size surface reached 1.75" aloft. At 2.75" — baseball — this is a severe hail signal associated with roof damage. Open it on the live map to see the swath over the streets.
A tornado was also reported to the National Weather Service during this storm. The ground reports below show where it was filed.
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Convective day · Apr 27, 2026 · noon–noon UTC
Severity
Overview's storm severity score weighs hailstone size, homes in the footprint, and ground-truth reports.
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
Each storm gets two readings: the radar signatures NEXRAD recorded as the cells passed overhead, and a modeled estimate of hail size in the air. They are independent surfaces, so a mismatch between them is expected — and worth reading.
Radar signature field The point detections NEXRAD recorded overhead. Each signature marks where the radar saw hail aloft — it is a detection, not a stone measured on the ground.
Estimated size field Radar-estimated hail size over the swath. The model reports the biggest stone the storm could sustain in the air; what actually fell may have been smaller.
The storm in context
This was Alton's 2nd recorded hail day, arriving 43 days after the Mar 15, 2026 storm. By severity it ranks 1st of the 5 storms we have logged here. Radar put the day's largest stone over Alton at 2.75" — the largest NEXRAD radar signature.
The Apr 27, 2026 convective day was bigger than Alton: the same system put hail over 1,188 other tracked cities, 336 of them in Illinois. Nearest: Bethalto (5 miles east, up to 2.5"); Hartford (7 miles south, up to 1.75"); Godfrey (9 miles northwest, up to 1.75").
These maps are stills. In the app this date is one of 5 Alton 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
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.
“A video from Alton showed the vortex of a waterspout tornado dissipating as it approached the Lincoln Shields Recreation Area. A NWS damage survey was unable to find an (LSX)”
— NOAA / SPC storm report
“(LSX)”
— NOAA / SPC storm report
“(LSX)”
— NOAA / SPC storm report
“Report from mPING: Golf Ball (1.75 in.). (LSX)”
— NOAA / SPC storm report
“(LSX)”
— NOAA / SPC storm report
“(LSX)”
— NOAA / SPC storm report
“Hail from the sizes of dimes to quarters. (LSX)”
— NOAA / SPC storm report
“Report from mPING: Ping Pong Ball (1.50 in.). (LSX)”
— NOAA / SPC storm report
“(LSX)”
— NOAA / SPC storm report
“Report from mPING: Quarter (1.00 in.). (LSX)”
— NOAA / SPC storm report
“(LSX)”
— NOAA / SPC storm report
Storm forensics
Read from the arrival times and locations of the NOAA ground reports, not a radar-measured storm track.
Hail was reported over 21 minutes, from to .
Reports came from Bethalto, Wood River, Godfrey, and West Alton — beyond Alton itself.
Severe hail signal
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
Potential roof exposure
$111M
Potential roof exposure — 9,247 homes × the ~$12,000 industry-average hail roof claim. Exposure, not confirmed damage.
Close just 0.5% of the 9,247 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 $1,942 on top of the $150 plan.
Estimated-size surface 
Estimated-size surface 
Estimated-size surface 
Estimated-size surface Set your territory and alerts today. When hail hits, use Overview to choose your streets and get moving.
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Web trial: 7 days free. Card required. $150/month after the trial unless cancelled.