IEM Daily Bulletin for May 17 2026

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 17 May 2026

News

No news is good news

IEM Code Pushes <repo,branch> on Github

Timestamp	Repository	Message	Link
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Daily Feature

No feature posted

NWS Watch/Warning Summary for 12 AM 16 May 2026 - 12 AM 17 May 2026 CDT

	Summary		By WFO					Watches
Type	US	IA	ARX	DVN	DMX	OAX	FSD	US
Tornado	19	2	0	0	2	3	0	1
Svr Tstorm	241	25	0	2	15	35	1	4
Flash Flood	9	1	0	0	0	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: 250 Verified: 120 [48.0%]
Polygon Size Versus County Size            [26.2%]
Average Perimeter Ratio                    [33.1%]
Percentage of Warned Area Verified (15km)  [32.0%]
Average Storm Based Warning Size           [1049 sq km]
Probability of Detection(higher is better) [0.85]
False Alarm Ratio (lower is better)        [0.52]
Critical Success Index (higher is better)  [0.44]

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): 1,765
• Mastodon / Fediverse: 42
• Slack: 119
• Twitter/X: 9,484
• HTTP Webhooks: 221
• Weather.IM Jabber Chatrooms: 14,352