IEM Daily Feature
Wednesday, 19 August 2020

Derecho Profile

Posted: 19 Aug 2020 05:37 AM

The featured chart is a preliminary plot of height profile horizontal wind speed from the ISU "Talltower" facility in Story County (north of Ames). This tower is outfitted with many sensors at various heights and records wind speeds at one second refresh intervals. The chart uses this one second data along with six sensors at various heights to construct a two dimensional analysis of horizontal wind speed during the passage of the most gusty portion of the derecho at that location. Please note that sampling winds at this time resolution more represents gusts than sustained winds. You can see lots of crazy things happen including an initial gust front that rocketed near surface winds to near 90 MPH (11:23 - 11:24 AM) to only subside for a brief moment before the most intense winds arrived. This plot indicates 90+ MPH gusts got very close to the surface with 120+ MPH gusts briefly recorded some 375 feet above ground level.

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Tags:   2020derecho   talltowers