IEM Daily Bulletin for Aug 18 2025

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 18 August 2025

News

No news is good news

IEM Code Pushes <repo,branch> on Github

Timestamp	Repository	Message	Link
Aug 17 9:27 PM	iem,main	⬆️ Update ruff	Link
Aug 17 9:28 PM	iem,main	✨ Default to current UTC date	Link

Daily Feature

No feature posted

NWS Watch/Warning Summary for 12 AM 17 Aug 2025 - 12 AM 18 Aug 2025 CDT

	Summary		By WFO					Watches
Type	US	IA	ARX	DVN	DMX	OAX	FSD	US
Tornado	7	4	0	0	3	0	0	0
Svr Tstorm	98	2	0	2	0	0	3	1
Flash Flood	30	0	1	1	0	0	4	---

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

IEM Cow Report

SVR+TOR Warnings Issued: 102 Verified:  31 [30.4%]
Polygon Size Versus County Size            [22.7%]
Average Perimeter Ratio                    [27.8%]
Percentage of Warned Area Verified (15km)  [12.7%]
Average Storm Based Warning Size           [1503 sq km]
Probability of Detection(higher is better) [0.59]
False Alarm Ratio (lower is better)        [0.70]
Critical Success Index (higher is better)  [0.25]