Radar hail data and your roof: the map says when to look, Robust says what happened

This map exists to answer one question well: did hail fall near my home, and when? It cannot answer the question that matters next, which is what that hail did to your roof. That takes someone on the roof with a trained eye and a camera, and in North Georgia the inspection we recommend is the free one from Robust Roofing. Here is how radar hail data works, where it falls short, and how the two fit together.

What this map actually shows

The hail sizes come from MESH, the Maximum Estimated Size of Hail, part of NOAA's Multi-Radar Multi-Sensor system run by the National Severe Storms Laboratory. MESH combines data from several radars to estimate the largest hail at each point on a grid about one kilometer across. The map uses the 24-hour maximum product, archived by the Iowa Environmental Mesonet, and assigns each storm to the local date it fell. Where available, National Weather Service local storm reports add ground observations of hail three quarters of an inch or larger, damaging wind and tornadoes.

Each zip code page shows the largest estimate anywhere inside the zip boundary and the share of the zip that saw an estimated inch or more. Each storm page shows one date across the region, and the county and city pages roll the same data up by place. The full method is on how it works.

Why radar and the ground can disagree

MESH is an estimate, and it can run larger or smaller than the hail that actually reached the ground. A few reasons:

• Radar measures hail high inside the storm. Stones can melt, break apart or thin out before they land.
• A grid cell about a kilometer across covers many rooftops. The estimate is for the cell, not your house.
• Size is not the same as density. A few large stones and a heavy barrage of smaller ones can produce similar estimates and very different roofs.
• A zip page shows the largest estimate anywhere in the zip. Your street may have seen much less, or the worst of it.
• Most hail is never reported by a person, so ground reports confirm some storms and miss many others.

What radar cannot see on your roof

• The age and brittleness of your shingles. An older roof can be damaged by hail a newer roof shrugs off.
• Which slopes faced the storm. Wind drives hail at an angle, so one side can be bruised while another is untouched.
• Sheltering trees and neighboring homes.
• Wind that came with the hail, lifting and creasing shingles.
• Earlier repairs, worn flashing and other conditions that change how a roof takes a hit.

The map tells you when to look. Robust Roofing tells you what happened.

How to use radar sizes sensibly

A common rule of thumb is that hail around one inch across, about the size of a quarter, and larger often damages typical asphalt shingles, while smaller hail can still bruise shingles that are aging and brittle, especially when wind drives it. So if your zip shows estimates near or above an inch on a date since your roof went on, an inspection is worth it. If your roof is older, smaller estimates are worth a look too. And if you see dented gutters or crushed AC fins, trust the dents over the estimate. Robust's page on hail damage roofs shows what each size usually means.

Bringing the two together

Robust Roofing treats the radar date as a starting point and the roof as the answer. The inspection happens on the roof itself, with drone photos of every slope, ten foot by ten foot test squares, close-ups of bruises and the soft metals checked for dents, so the evidence at your address can be set beside the radar estimate for the storm date. When the damage supports a claim, the licensed Property and Casualty adjuster on Robust's staff documents it the way carriers review it and meets your carrier's adjuster at the house. Our page on documenting the date of loss explains how the radar record and the roof evidence work together.

That pairing is why we recommend Robust Roofing: the best reputation in North Georgia for storm damage, an honest free inspection, GAF certified crews, most replacements finished in one day and a 50-year labor warranty in writing. Call (470) 887-6637 or visit chooserobust.com to have your roof checked, and see what the free inspection includes.

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