IEM Daily Bulletin for Feb 27 2026

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 27 February 2026

News

No news is good news

IEM Code Pushes <repo,branch> on Github

Timestamp	Repository	Message	Link
Feb 26 8:02 AM	iem,main	🩹 Prevent NaN	Link
Feb 26 10:49 AM	iem,main	⬆️ Update precommits	Link
Feb 26 10:50 AM	iem,main	📝 Sundry updates per log review	Link
Feb 26 11:01 AM	iem,main	🚧 Iterate on CLI Audit	Link
Feb 26 2:58 PM	iem,main	📝 Sundry rollups per review	Link
Feb 26 9:55 AM	iem-database,main	🎨 Apply sqlfluff	Link
Feb 26 9:57 AM	iem-database,main	🐛 Address gdd handling of low over ceiling This is rare, but makes things consistent with pyiem. refs akrherz/pyIEM#1156	Link

Daily Feature

'25-'26 Winter Storm #17
Date: 26 Feb 08:29 AM
Votes: Good: 12   Bad: 2 Abstain: 1

A quick moving system brought a stripe of light snow over Iowa on Wednesday afternoon into the evening. The system produced the arbitrary two inch snowfall minimum report to trigger the IEM winter storm accounting, so here we are with a map! This isolated two inch report as near Marshalltown (NE of Des Moines). There was some freezing rain associated with this system as well. State winter road conditions check normal this morning as this nuance snow event was cleared away.

NWS Watch/Warning Summary for 12 AM 26 Feb 2026 - 12 AM 27 Feb 2026 CST

	Summary		By WFO					Watches
Type	US	IA	ARX	DVN	DMX	OAX	FSD	US
Tornado	0	0	0	0	0	0	0	0
Svr Tstorm	48	0	0	0	0	0	0	0
Flash Flood	1	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:  48 Verified:  25 [52.1%]
Polygon Size Versus County Size            [25.7%]
Average Perimeter Ratio                    [29.1%]
Percentage of Warned Area Verified (15km)  [31.5%]
Average Storm Based Warning Size           [955 sq km]
Probability of Detection(higher is better) [0.87]
False Alarm Ratio (lower is better)        [0.48]
Critical Success Index (higher is better)  [0.48]

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): 1,377
• Mastodon / Fediverse: 3,668
• Slack: 103
• Twitter/X: 10,619
• HTTP Webhooks: 226
• Weather.IM Jabber Chatrooms: 11,288