IEM Daily Feature
Monday, 17 August 2020

90 MPH SVR Warning

Posted: 17 Aug 2020 05:46 AM

When the National Weather Service issues Severe Thunderstorm (SVR) Warnings, they include tags that denote the forecast max hail size and wind gust. These tags are useful to understand the threat posed by a storm and some communities trigger their outdoor sirens for SVR's with wind tags at or above 70 MPH. The featured chart presents the warning count frequency of the combination of hail and wind gust tags for SVR warnings issued by NWS Des Moines. Each warning contains both a wind gust and hail tag, so they can be compared in this manner and only the tag values at issuance are included in this chart. For the Derecho last Monday (wow, has it been a week already?!?!), NWS Des Moines issued one such warning with a 90 MPH wind gust tag. The first such usage since these tags came into operations.

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Tags:   2020derecho