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Enhanced Product National Implementation of the use of 1 inch Diameter Hail Criteria
Data Mining Tool
Outreach / Education
The Severe Thunderstorm Warning (SVR) is an alphanumeric product providing short-fused warning information on hazardous conditions associated with thunderstorms which are expected to pose a threat to life and/or real property. This product is prepared by each National Weather Service (NWS) Weather Forecast Office (WFO) for their County Warning Area (CWA) of responsibility. A Severe Thunderstorm Warning (SVR) is issued based on expectation of winds gusting to 58 mph or greater and/or hail of one (1) inch diameter (U.S. quarter-size) or greater. Prior to January 5, 2010, the hail criterion for a severe thunderstorm was three-quarters of an inch diameter (U.S. penny-size) or greater. The change in the minimum hail criterion for the Severe Thunderstorm Warning from three-quarter inch (U.S. penny-size) to one inch (U.S. quarter-size) was based on research indicating significant damage does not occur until hail size reaches 1 inch in diameter and in response to requests by core partners in emergency management and the media. No change was made to the wind criterion of 58 mph.
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Comment Start Date:
0000-00-00 Comment End Date: 0000-00-00
David Caldwell OCWWS Dir
Approved for Operational Implementation
Last edit date to this meta-data: 2019-07-01