Hail occurrence and severity

HailTrace provides live and archived event-specific meteorologist-created hail maps showing affected areas and hail size/intensity. Its method combines radar analysis with verified ground reports and photos, including maximum-hail-size verification; maps update in real time and the archive extends to 2010.

Open event-detail and location files identify NWS-documented Hail events by event/episode id, begin/end time, and linked locations. MAGNITUDE records maximum reported hail size in inches; reporting source, modification/certification timestamps, and dated release pin the answer. This is reported/certified evidence, not a radar-estimated swath.

The credentialed Xweather Weather API returns U.S. NWS storm reports since 1950 with identity, coordinates, time, type/category, reporter, and hail size. Its separate latest-only NEXRAD storm-cell module supplies observation time, radar/cell identities, position, and maximum hail size. Reported and radar-derived modes and the latest-only limit must remain distinct.

GET /hail accepts an arbitrary address or coordinate, date range, and 0.1–200 mile radius and returns the matched location plus each hail date and daily maximum hail size. This is point-and-radius occurrence evidence, not continuous footprint geometry.

For a buyer-selected U.S. address or coordinate and search period, HailFACTS lists dated hail rows and maximum estimated hail size at the selected location and within one, three, and ten miles. This is point-and-radius model-derived evidence, not continuous geometry or measured ground truth.

For a UTC-pinned U.S. grid and interval, MRMS Version 12.2 publishes Maximum Estimated Size of Hail in mm and 30-/60-minute MESH hail-swath grids on a documented two-minute cycle. This is Strong radar/multi-sensor estimated location and severity evidence, not reported ground truth.

OneSite attributes a selected site by coordinates and reports dated hail activity, stated nearby scope, maximum hail size, storm timing and movement, intensity scale, report/version/verification pins, and radar/source context. It is radar-derived event evidence, not a measured continuous swath.

For a date/time-identified event, SPC hail rows provide reported occurrence coordinates, time, and hail diameter, with archive release pinning record vintage. They support reported locations rather than a continuous swath, affected boundary, or building-impact match.

For an arbitrary selected location and search period, the Basic hail report supplies report date, matched address/coordinates, dated local-time hail rows, and maximum hail size at the location and stated radii, with ground-report and/or radar-algorithm basis. It is not continuous geometry.

With event reports enabled, a buyer can query a U.S. location/date range for hail reports. Returned events identify time, coordinates, distance from the requested location, and reported hailstone size where available, directly supporting where, when, and at what reported severity hail occurred.

NOAA NCEI archived Level-III Hail Index products locate radar-observed storms and classify hail potential as probable or positive; files are selected by radar site and volume-scan/file time. This is useful radar-derived occurrence and categorical-threshold evidence, not a ground report or measured hail size.