Hail-claim verification

Goal: produce a defensible corroborated / partially corroborated / not corroborated verdict for a hail claim at a specific location and date, with the evidence and its distance/time from the claimed loss.

Reminder: SHEARLINE data is informational and preliminary (NWS/spotter reports), not a legal adjudication or the final NCEI Storm Events record. State that in the output.

Inputs you need

• Location — a street address or place. Geocode it to lat, lon (decimal degrees,

CONUS only; longitude is negative in the US).

• Date of the alleged hail — a single UTC calendar day, YYYY-MM-DD. If the

claimant gives a local date/time near midnight, check the adjacent UTC day too.

• Claimed hail size (optional, inches) — to compare against reports.

Procedure

1. Pull ground-truth reports for that day.

get_historical_storm_reports(lat, lon, date, radius_km=40)

• Read data.counts.hail and the data.reports entries with category: "hail".
• For each hail report note magnitude (inches), time_utc, and distance_km /

direction from the claim location.

1. If the event was within the last ~24 hours, add radar-derived hail.

get_mrms_severe(lat, lon, radius_km=40)

• data.hail_mesh.max_mesh_in is the radar Maximum Estimated Size of Hail in the

last hour, with the distance/bearing of the maximum. (MRMS only retains ~24–48 h, so this step applies to recent claims only; for older dates rely on step 1.)

1. Widen if nothing close. If no hail report is within ~15 km, re-run step 1 with

radius_km=80 to see whether a hail swath passed nearby (hail is highly localized; a report 30 km away is weak support).

1. Form the verdict.

• Corroborated — a hail report (or MESH ≥ 1") within ~15 km and within a few

hours of the claimed time, of comparable or larger size.

• Partially corroborated — hail reported in the broader area (15–40 km) or of

smaller size than claimed.

• Not corroborated — no hail reports within 40 km on that UTC day (note that

pre-2005 dates aren't covered, and an empty old-date result is not proof of a quiet day).

Output template

Hail-claim verification — <address> (<lat>, <lon>), <date> UTC
Verdict: <corroborated | partially corroborated | not corroborated>
Evidence:
  - <n> hail report(s) within 40 km; largest <size>" at <time_utc>, <dist> km <dir>
  - [if recent] MRMS MESH max <x>" (<dist> km <dir>) in the last hour
Nearest report to the loss: <size>" at <time_utc>, <dist> km <dir>
Caveats: preliminary NWS/spotter + radar data; not the final NCEI record;
         hail is localized so distance matters.