IEM Daily Bulletin for Jun 5 2026

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 05 June 2026

News

No news is good news

IEM Code Pushes <repo,branch> on Github

Timestamp	Repository	Message	Link
Jun 4 10:56 AM	iem,main	🎨 Polish app and permit overlap specification	Link
Jun 4 11:04 AM	iem,main	🎨 Cleanup doc and remove legacy iemapps_tags usage	Link
Jun 4 1:33 PM	iem,main	🐛 Address date edge case and check WS/json decode	Link
Jun 4 9:55 PM	iem,main	✨ Add first/last side panels to ISU SM Plot https://mesonet.agron.iastate.edu/agclimate/smts.php?opt=sm	Link
Jun 4 10:07 PM	iem,main	🐛 Fix SQL for time period over 1 year	Link
Jun 4 10:07 PM	iem,main	⬆️ Update ruff precommit	Link
Jun 4 9:35 AM	iem-database,main	⬆️ Update precommits	Link
Jun 4 9:41 AM	iem-database,main	✨ Build out iemapps metadata storage Adds category,subcategory,tags,importances and updates to text types. Also merge legacy iemapps_tags storage	Link

Daily Feature

High Watch Percentage
Date: 04 Jun 05:30 AM
Votes: Good: 11   Bad: 0 Abstain: 3

It has been a somewhat strange year for severe weather to date for the United States. April was very busy for severe weather in and around Iowa, but it continued to be mostly quiet over the southeastern US. May was about the exact opposite of April with much quieter weather, but also for much of the rest of the country as well. The featured chart looks into an aspect of this by totaling up the number of Severe Thunderstorm and Tornado watches issued by the Storm Prediction Center for the year to date period. The top panel shows the total number of watches with the second panel totaling the number of watch outline polygons (note they are no longer the official watch area, but a close approximation) that touched Iowa. The bottom panel plots the percentage touching Iowa. Interestingly, 2026 comes in with the highest percentage since 2004!

The featured media can be generated on-demand here

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NWS Watch/Warning Summary for 12 AM 4 Jun 2026 - 12 AM 5 Jun 2026 CDT

	Summary		By WFO					Watches
Type	US	IA	ARX	DVN	DMX	OAX	FSD	US
Tornado	8	1	0	0	0	1	0	0
Svr Tstorm	67	0	0	0	0	0	8	2
Flash Flood	18	1	0	0	0	1	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:  73 Verified:  31 [42.5%]
Polygon Size Versus County Size            [15.4%]
Average Perimeter Ratio                    [23.3%]
Percentage of Warned Area Verified (15km)  [19.6%]
Average Storm Based Warning Size           [1235 sq km]
Probability of Detection(higher is better) [0.71]
False Alarm Ratio (lower is better)        [0.58]
Critical Success Index (higher is better)  [0.36]

IEMBot Social Media Posts

IEMBot can be configured to post messages to a number of social media services. More details: IEMBot Homepage.

Posts yesterday per supported service:

• ATMosphere (bluesky only attm): 1,910
• Mastodon / Fediverse: 12
• Slack: 74
• Twitter/X: 7,899
• HTTP Webhooks: 165
• Weather.IM Jabber Chatrooms: 10,488