IEM Daily Bulletin for Jun 21 2026

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 21 June 2026

News

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Daily Feature

107 MPH Gust
Date: 20 Jun 05:30 AM
Votes: Good: 5   Bad: 0 Abstain: 0

There continues to be no shortage of interesting things to denote from the storms of last Wednesday (17 June 2026) including low June surface pressure and a rapid change in dew point. Today's featured chart looks into the wind reports from the Marshalltown Airport. A gust of 107 MPH is shown at 5:48 AM with a sustained peak wind speed of 68 MPH just a few minutes prior. NWS Des Moines has an excellent event summary page with more details on this damaging wind event.

The featured media can be generated on-demand here

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NWS Watch/Warning Summary for 12 AM 20 Jun 2026 - 12 AM 21 Jun 2026 CDT

	Summary		By WFO					Watches
Type	US	IA	ARX	DVN	DMX	OAX	FSD	US
Tornado	8	0	0	0	0	0	0	1
Svr Tstorm	162	0	0	0	0	2	0	5
Flash Flood	39	0	0	0	0	0	0	---

ARX = LaCrosse, WI DVN = Davenport, IA DMX = Des Moines, IA OAX = Omaha, NE FSD = Sioux Falls, SD

IEM Cow Report

SVR+TOR Warnings Issued: 161 Verified:  83 [51.6%]
Polygon Size Versus County Size            [26.0%]
Average Perimeter Ratio                    [28.7%]
Percentage of Warned Area Verified (15km)  [17.0%]
Average Storm Based Warning Size           [2776 sq km]
Probability of Detection(higher is better) [0.81]
False Alarm Ratio (lower is better)        [0.48]
Critical Success Index (higher is better)  [0.46]

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