Trained spotter
Definition
- Related pages
- 5
- Last revised
- 23 August 2026
A trained spotter is a volunteer who has attended the National Weather Service's spotter training, usually a short class given each spring by the local forecast office, and who reports severe weather to that office by the methods the class teaches: how to measure a hailstone and what to compare it with, how to tell a wall cloud from scud, when a gust counts as severe and how to estimate one from what it damaged. The office knows who its spotters are and where they are, which is why a report attributed to a trained spotter is given more weight in review than one from the public.
The attribution is recorded with the report. The national storm database names the source of each entry in a fixed vocabulary, of which trained spotter is one value beside law enforcement, emergency manager, broadcast media, cooperative observer, the public and several others, and the storm report logs carry the same attribution where the office included it. A reader checking a report can therefore see not just what was reported but by what kind of observer.
Training is not instrumentation. A trained spotter's hail size is a comparison or a ruler reading made under pressure; a trained spotter's wind figure, unless read from an instrument, is an estimate from damage. The record files both as ground observations, measured, because a person at the place recorded them, and the product keeps them on that side of the line while saying plainly what kind of measurement each is.
In the report
How the document prints it
The report does not label individual rows by observer type; a trained spotter's hail appears in the record table as a ground observation with its date, measurement, distance, bearing and source, marked as measured, and the citation for that source under Sources and method describes the kind of observer the source draws on. A reader who needs the attribution of one report follows the citation to the federal record, where it is held against the entry.
Related
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
Spotter report
An eyewitness report of hail, wind or a tornado made by a person at the scene and passed to a forecast office, with the place and time attached.
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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
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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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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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
- The archive holds nothing this page could show yet, so no example is printed. One appears, computed rather than written, as soon as the record holds a relevant day.
- 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.