Spotter report
Definition
- Related pages
- 5
- Last revised
- 23 August 2026
A spotter report is what a person saw or measured, sent to the forecast office that covers the place: hail held against a coin or a ruler, a gust read off a home instrument or judged from what it brought down, a funnel or a tornado and where it was. The office relays it as a local storm report, and from there it is reviewed and carried into the national storm database. Most of the ground record of hail begins this way, because no instrument network measures hail on the ground at a density that reaches most roofs; for most of the country a spotter is the instrument.
What a spotter report attests is narrow and strong. It attests that at a place, at a time, a person observed the thing reported, and where a size is given, that the person measured or compared it. It does not attest the size at any other place, the stone that fell in the next street, or the duration of the fall. A stone picked up after a pause has melted; a size named from memory has grown. The honest reading of a spotter report is a point: this, here, then.
What fails in a spotter report is the stone, not the witness: picked up after the fall, compared against a coin while it melts, or sized from memory. The record keeps the size as filed and does not correct it. Several people reporting one storm through different channels are that many independent sources; one report relayed by three feeds is still one.
In the report
How the document prints it
In the report a spotter report is a row in the record table with its date, its measurement, its distance and bearing from the address and the source that carried it, marked as measured. In the findings it counts as one kind of evidence, a ground observation, however many rows of it there are; confidence is graded on how many independent kinds agree, so a spotter's hail beside a radar detection and an official warning reads as strongly corroborated and three spotters alone read as a single kind. The report records what the spotter filed and does not adjust it.
From the record
14 Mar 2025
The day with the most reports on record
- Reports on the day
- 4,810
- Hail reports
- 1,111
- Largest measured on the ground
- 2.75″
- Independent sources
- 3
14 March 2025 carries 4,810 reports, more than any other day on record, 1,111 of them hail, filed under 27 states and carried by 3 independent sources. Each is a point with a place, a date and a time, and the largest measured size is one a person or an instrument recorded.
Measured Detected, not measured
The page these figures come fromRelated
The terms this page uses and the guides that go further. Each is shown against its own example from the record.
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Term
Trained spotter
A volunteer who has completed National Weather Service spotter training and reports severe weather to a forecast office by an agreed method.
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Term
Local storm report
A report of severe weather at a place and a time, relayed by a National Weather Service office as it comes in and before it is reviewed.
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Term
Hail size
The diameter of the largest hailstone at a place, reported in inches or by the named object on the spotter chart it was compared with.
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Term
Cooperative observer
A volunteer who takes daily weather measurements at a fixed site with issued instruments and files them with the National Weather Service.
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Guide
Measured and detected: radar hail sizes against spotter reports
The record keeps a stone measured on the ground apart from a size computed from radar, because a court will ask which is which. This guide names the kinds of evidence as the report names them, states what a radar-derived size can and cannot say, explains why a measurement is drawn as a filled mark and a detection as a hollow one, and shows how to read the two on the same day.
Sources
The primary references. Each opens on the agency's own site.
The glossary defines the word. The report is what uses it.
Everything above is definition: what the word means in the document, and what it does not. None of it says what reached one roof.
Run the address and the archive is searched at the property: the storm, the date, the measured size, the distance and bearing from the roof, and the federal record each figure came from, in a document that states its own method. About a minute.
How this page is made
- The text
- Written by the editors and last revised 23 August 2026. It explains the record and how the report reads it; it contains no figure of its own.
- The example
- Drawn from the archive when the page was compiled, 24 August 2026, and rebuilt daily as the record deepens. Every figure in the panel marked From the record is computed, not written, and links to the page it came from.
- Measured and detected
- A report from a person or an instrument is measured. A radar-derived size is detected, not measured, and is marked as such, here and in every document we issue. The two are never added together.
- What this is not
- A definition of a word the report uses. It is not a report on any property, and it states no opinion about one. The coverage page states what the record holds, by kind and by year.
About this record
Everything here is reproduced from public federal and volunteer weather records, as the agencies and observer networks that publish them released it. Titan Weather compiles the record; it does not observe the weather, and it is not affiliated with any source it cites.
No archive holds everything. Storms cross places where nobody is standing, instruments and spotters cover some areas better than others, sources revise their records, and recent reports can take weeks to arrive and settle. Where this page shows nothing, nothing was found in the sources searched, within the period and area it states. That is not a finding that no weather occurred.
These pages describe the public record near a place or on a date. They do not establish what reached any particular property, and nothing here is insurance, legal or engineering advice.