IEM Daily Bulletin for Jun 12 2026

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 12 June 2026

News

No news is good news

IEM Code Pushes <repo,branch> on Github

Timestamp	Repository	Message	Link
Jun 11 11:18 PM	iemlsr,main	✨ Add draw rectangle and get counts tool	Link
Jun 11 11:19 PM	iemlsr,main	⬆️ Update eslint precommit	Link
Jun 11 11:27 PM	iemlsr,main	💚 Address codereview	Link

Daily Feature

Busy June Day
Date: 11 Jun 05:20 AM
Votes: Good: 17   Bad: 0 Abstain: 0

Multiple rounds of severe weather impacted Iowa and beyond on Wednesday with more severe weather expected today. The featured chart presents the number active Severe Thunderstorm, Tornado, and Flash Flood Warnings issued by the National Weather Service by minute between 5 AM yesterday morning till this morning. The data is presented as a stacked bar chart. The chart shows a typical severe weather life cycle with warnings first dominated by Severe Thunderstorm Warnings with a few Tornado warnings coming a bit later and then a transition to mostly Flash Flood Warnings as the accumulated effect of heavy rainfall associated with the storms produces flash flooding. Two rounds of rough weather are expected for Iowa today with the first already ongoing over southeastern Nebraska and southwestern Iowa, which will lift northeast. A second round is expected to fire early afternoon along a front that will sweep the state.

The featured media can be generated on-demand here

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NWS Watch/Warning Summary for 12 AM 11 Jun 2026 - 12 AM 12 Jun 2026 CDT

	Summary		By WFO					Watches
Type	US	IA	ARX	DVN	DMX	OAX	FSD	US
Tornado	78	15	0	8	6	6	0	3
Svr Tstorm	352	47	2	12	17	17	0	8
Flash Flood	39	10	0	4	1	4	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: 418 Verified: 214 [51.2%]
Polygon Size Versus County Size            [40.2%]
Average Perimeter Ratio                    [37.7%]
Percentage of Warned Area Verified (15km)  [28.6%]
Average Storm Based Warning Size           [2094 sq km]
Probability of Detection(higher is better) [0.92]
False Alarm Ratio (lower is better)        [0.49]
Critical Success Index (higher is better)  [0.49]

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