IEM Daily Bulletin for Jun 19 2026

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 19 June 2026

News

No news is good news

IEM Code Pushes <repo,branch> on Github

Timestamp	Repository	Message	Link
Jun 18 9:17 AM	pyiem,main	✨ Introduce pyiem.web for common web handlers - centralizes iemweb error_log here - centralizes iemwebfarm error404 here	Link
Jun 18 12:20 PM	pyiem,main	📝 Tweak generated error_log messages	Link
Jun 18 7:26 AM	pywwa,main	⬆️ Update precommits	Link
Jun 18 7:27 AM	pywwa,main	📝 Add CJJ3	Link
Jun 18 7:28 AM	pywwa,main	🚀 Denote 1.7.2 Release	Link

Daily Feature

Minimum June Pressure
Date: 18 Jun 05:30 AM
Votes: Good: 9   Bad: 1 Abstain: 0

It was an energetic day of weather across Iowa and beyond on Wednesday. The day started with a strong complex of storms diving south during the early morning hours and producing damaging winds along with significant rainfall. This complex greatly altered the placement of the afternoon round of severe storms with the most damaging staying south of Iowa. A few storms were able to develop over far northeastern Iowa during the afternoon hours and even likely produced a significant tornado. The storm complex was associated with a low pressure system that was more typical of April than mid June for Iowa. The pressure was very low for June as shown by the featured chart of top 10 lowest pressure altimeter values for Mason City (NC Iowa). Yesterday comes in as the fifth lowest date since 1940 during June!

The featured media can be generated on-demand here

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NWS Watch/Warning Summary for 12 AM 18 Jun 2026 - 12 AM 19 Jun 2026 CDT

	Summary		By WFO					Watches
Type	US	IA	ARX	DVN	DMX	OAX	FSD	US
Tornado	88	0	0	0	0	0	0	5
Svr Tstorm	251	0	0	0	0	0	0	1
Flash Flood	86	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: 336 Verified: 153 [45.5%]
Polygon Size Versus County Size            [34.2%]
Average Perimeter Ratio                    [25.7%]
Percentage of Warned Area Verified (15km)  [26.3%]
Average Storm Based Warning Size           [2052 sq km]
Probability of Detection(higher is better) [0.79]
False Alarm Ratio (lower is better)        [0.54]
Critical Success Index (higher is better)  [0.41]

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