NOAA storm reports vs. hail pad networks for mapping a hail swath

A hail event rolls through at 4 p.m., and by the next morning your queue has three hundred new claims from four different counties. Somebody on the team pulls up the NOAA storm reports to see how big the hail was. Somebody else mentions a hail pad network that caught a 2-inch stone twelve miles away. Neither one tells you which of the three hundred addresses needs an adjuster today.

What a NOAA storm report records

The Storm Prediction Center's reports come from spotters, broadcast mets, county EMAs, and the public, phoned or texted in during or right after the event. That's a strength for building the historical record and a weakness for triage. Hail size in a report is usually rounded to a common reference, penny, quarter, golf ball, because that's what the caller had on hand to compare it to, not because a 1.5-inch stone and a 1.75-inch stone look the same on a shingle. Location is often tied to the nearest named town or a highway mile marker, not a street address, because the person calling it in doesn't know they're also marking a claims boundary for an insurer three states away.

That's fine for confirming an event happened and roughly where. It's not built to tell you whether the hail that hit Main Street also hit the subdivision two miles northeast, or stopped short of it entirely.

Hail pad data accuracy and the coverage problem

A hail pad gives you something a phoned-in report can't: a physical measurement at a fixed point, styrofoam or soft aluminum that records size and count of every stone that hit it. Where a pad exists, the reading is solid. The problem is where pads exist. Mesonet and university networks place pads based on research funding and station maintenance, not on where next Tuesday's supercell is going to track. A dense network might have stations every few miles in one county and none at all forty miles west. A swath boundary built from pad data follows the gaps between those instruments, straight lines connecting points that happened to have a pad, and misses whatever shape the cell traced across the rooflines in between.

Both sources are doing their job. Neither one was built to tell a catastrophe team which addresses to dispatch first.

Neither source maps a roof

Here's the gap that matters for claims: a storm report says hail fell near a town. A pad says hail of a certain size hit a specific point. Neither says whether the ridge caps on 1420 Elm Street got displaced, or whether the hail bruised the mat on a ten-year-old roof versus just dinging the gutters. That distinction, between confirmed damage and confirmed weather, is the whole difference between a queue sorted by guesswork and a queue sorted by what's actually sitting on each roof.

That's the gap a flyover of the full event swath is built to close, address by address, the morning after, before the first truck leaves the lot.

If your queue is still being sorted off a storm report radius and a hope, it's worth seeing what a numbered memo of the swath looks like instead.