What Is a Hail Swath?
A hail swath is the path along the ground covered by hail as a storm moves through — typically a long, narrow corridor that can stretch for miles but be only a fraction of a mile wide. Swaths explain why one street gets pounded while a home a mile away sees nothing.
Why hail falls in a path
Hail forms in the strong updraft of a thunderstorm. As the storm moves, the zone capable of producing and dropping large hail sweeps across the ground, laying down a track. Because the storm is moving and the hail core is relatively narrow, the result is a corridor — the swath — rather than an even blanket.
Why your neighbor's experience can differ from yours
Hail size and intensity can change dramatically over short distances. The center of a swath may see baseball-size hail while the edge a few blocks away sees only pea-size. This is exactly why address-level data matters: a city-wide or ZIP-code average hides the reality that hail exposure varies block by block.
HailScore maps individual hail events near your specific address and weights them by distance, so a swath that clipped your street shows up even if the rest of town was spared.
How swaths are mapped
Radar products like MRMS MESH render swaths as color-ramped polygons keyed to the maximum estimated hail size, and the NEXRAD archive captures the historical tracks. HailScore's professional view combines live MRMS swaths with more than a decade of NEXRAD radar history.
Frequently asked questions
How long can a hail swath be?
Swaths commonly run for tens of miles as a storm travels, while staying only a fraction of a mile to a few miles wide. Long-track supercells can produce swaths well over a hundred miles long.
Why does HailScore use address-level data instead of ZIP codes?
Because hail swaths are narrow, two homes in the same ZIP code can have completely different hail exposure. Address-level analysis captures that difference; a ZIP average does not.
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