IEM Daily Bulletin for Feb 26 2026

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 26 February 2026

News

No news is good news

IEM Code Pushes <repo,branch> on Github

Timestamp	Repository	Message	Link
Feb 25 2:33 PM	iem,main	🐛 Fix Cold Weather Advisory plotting https://mesonet.agron.iastate.edu/plotting/auto/?q=232	Link
Feb 25 2:33 PM	iem,main	📝 Sundry updates per log review	Link
Feb 25 2:42 PM	iem,main	💚 Fix typo	Link
Feb 25 11:49 PM	iem,main	🚧 Add NWS CLI Audit Trail on Daily high/low https://mesonet.agron.iastate.edu/nws/cli-audit/	Link
Feb 25 11:51 PM	iem,main	💚 Address deepsource concerns	Link
Feb 25 8:13 AM	iem-web-services,main	⬆️ Update ruff	Link

Daily Feature

Stripe of Cooler Temps
Date: 25 Feb 05:30 AM
Votes: Good: 18   Bad: 0 Abstain: 0

The presence of snow cover makes a major difference to the surface energy budget with the most noticeable impact for humans being the air temperature experienced. The weather yesterday was a great illustration as shown by the featured map plotting Terra MODIS satellite imagery from Sunday (chosen due to fewer clouds than Monday or Tuesday) and airport high temperatures on Tuesday. The most recent snow storm produced a stripe of snow bisecting Iowa and nicely shown by the satellite imagery. The impact on Tuesday high temperatures is readily apparent with far SE and NW Iowa enjoying highs in the 50s with the snow covered regions struggling in the 30s and lower 40s.

NWS Watch/Warning Summary for 12 AM 25 Feb 2026 - 12 AM 26 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	2	0	0	0	0	0	0	0
Flash Flood	0	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:   2 Verified:   1 [50.0%]
Polygon Size Versus County Size            [39.2%]
Average Perimeter Ratio                    [22.8%]
Percentage of Warned Area Verified (15km)  [10.2%]
Average Storm Based Warning Size           [6277 sq km]
Probability of Detection(higher is better) [0.50]
False Alarm Ratio (lower is better)        [0.50]
Critical Success Index (higher is better)  [0.33]

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): 1,400
• Mastodon / Fediverse: 3,230
• Slack: 116
• Twitter/X: 8,969
• HTTP Webhooks: 10
• Weather.IM Jabber Chatrooms: 9,127