IEM Daily Bulletin for Mar 17 2026

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 17 March 2026

News

No news is good news

IEM Code Pushes <repo,branch> on Github

Timestamp	Repository	Message	Link
Mar 16 11:43 AM	iem,main	📝 Sundry updates per log review	Link
Mar 16 2:44 PM	iem,main	⚡️ Add request size constraint on RWIS archive dl https://mesonet.agron.iastate.edu/cgi-bin/request/rwis.py?help	Link
Mar 17 6:52 AM	iemvtec,main	🐛 Increase WFO select options closes #48	Link
Mar 17 6:54 AM	iemvtec,main	⬆️ Update eslint	Link
Mar 17 6:57 AM	iemvtec,main	💚 Address pre-commit issue	Link

Daily Feature

'25-'26 Winter Storm #20
Date: 16 Mar 08:06 AM
Votes: Good: 15   Bad: 1 Abstain: 0

Nothing like a good ole fashioned plains blizzard to remind everyone that we are not done with winter yet. The featured map attempts to analyze available snowfall reports from the NWS and CoCoRaHS, but will need updated later this Monday after more reports are received. Most of this now fell sideways and over along duration, which makes for difficult measurement and reporting. For Iowa, the highest snowfall totals were isolated to far eastern and northern Iowa. The lesser totals over the rest of the state still had a significant impact as strong winds and frigid temperatures have iced up practically all the roads for the state. The current map does indicate some areas without measurable snowfall, but more reports received later today will likely fill those in with at least measurable totals. Much warmer weather will quickly return this week.

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

	Summary		By WFO					Watches
Type	US	IA	ARX	DVN	DMX	OAX	FSD	US
Tornado	53	0	0	0	0	0	0	7
Svr Tstorm	272	0	0	0	0	0	0	2
Flash Flood	3	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: 324 Verified: 180 [55.6%]
Polygon Size Versus County Size            [48.6%]
Average Perimeter Ratio                    [35.1%]
Percentage of Warned Area Verified (15km)  [24.6%]
Average Storm Based Warning Size           [2720 sq km]
Probability of Detection(higher is better) [0.80]
False Alarm Ratio (lower is better)        [0.44]
Critical Success Index (higher is better)  [0.49]

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