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Reconstructing what happened in the sky above a specific address, on a specific date, months or years after the fact is the work of forensic meteorology. It is a specialized application of atmospheric science that draws on the same data the National Weather Service uses operationally, but applies it retrospectively to answer a narrower and more precise question than a forecast ever needs to.
The core data sources are consistent across most analyses. NEXRAD radar archives provide reflectivity and dual-polarization data that can be used to estimate hail presence and probable size along a storm’s track. Surface station observations from airports and automated weather stations record wind gusts, precipitation, and barometric pressure at fixed points. Satellite imagery adds a broader view of storm structure and movement, while storm reports submitted to the National Weather Service by trained spotters, emergency management, and the public provide ground-level corroboration. A forensic meteorologist typically layers these sources to build a timeline showing when a storm cell passed over a given set of coordinates and what conditions likely existed at that moment. Archived climate records covering temperature, precipitation totals, and prior conditions can also help place a single storm event within a broader seasonal pattern when that context is relevant to a given question.
Radar-derived hail estimates, often produced through algorithms such as Maximum Estimated Size of Hail, are probabilistic rather than a direct measurement of stones on the ground. Reflectivity and polarization signatures correlate with hail presence and rough size ranges, but the algorithm output requires interpretation and calibration against ground truth reports where they exist. Wind analysis carries similar caveats, since a station reading several miles from a property does not guarantee identical conditions at the site itself. A qualified analysis accounts for these gaps explicitly rather than presenting modeled output as certainty, stating a range or confidence level rather than a single definitive figure wherever the underlying data supports nothing more precise.
When a forensic meteorologist’s work moves into litigation or a formal appraisal proceeding, the underlying methodology often gets examined as closely as the conclusion itself. That can include the specific radar products relied on, the version of any hail-size algorithm used, how gaps in station coverage were handled, and whether the analyst’s conclusions are stated with appropriate qualification given the known limits of the data. An analysis that clearly documents its sources, assumptions, and margins of uncertainty tends to hold up better under that kind of scrutiny than one that presents a single number without explaining how it was derived, regardless of which party retained the analyst.
These reconstructions are used across property claims, litigation, and appraisal in various ways, most often to establish whether a storm capable of producing the claimed damage passed near a property on the date in question. That is useful, technical information. It is not, by itself, a determination of what damage exists on a given roof or wall, nor does it resolve questions of coverage, which remain matters for the policy language and the parties to work through separately from the meteorological record.
This article is general education about how the appraisal process commonly works. It is not legal advice, and specific procedures can vary by state and policy.
Russ Lis is a working property insurance appraiser and umpire based in Minnesota, serving clients nationwide. Contact Appraisal Resolution.