IEM Daily Bulletin for May 23 2026

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 23 May 2026

News

No news is good news

IEM Code Pushes <repo,branch> on Github

Timestamp	Repository	Message	Link
May 22 4:37 PM	pywwa,main	⬆️ Bump ruff, add CGR3	Link
May 22 11:46 AM	iem-web-services,main	⚡️ Update sharing locations, dedicated /nws/bufkit	Link
May 22 11:47 AM	iem-web-services,main	⬆️ Update ruff	Link
May 22 12:15 PM	iem-web-services,main	✏️ Fix location typo	Link

Daily Feature

Plenty of Red
Date: 22 May 05:30 AM
Votes: Good: 14   Bad: 0 Abstain: 0

The featured map presents May to date precipitation departures courtesy of PRISM. There is plenty of red (below average departures) to be found on the map. Outside of the rainfall events of last weekend, there has not been much to speak of for rain during May. Much of Iowa is surviving from the very wet April and the periods of reduced water demand like what was found this week with the cool and cloudy conditions. The precipitation forecast for the rest of May is not that bullish and temperatures will be increasing, which will start to materialize impacts over the driest parts of the state this May. For this time of year, it roughly takes about an inch of rain per week just to keep up with climatology, so departures can rapidly build when we get dry periods during the wettest portion of the year!

The featured media can be generated on-demand here

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NWS Watch/Warning Summary for 12 AM 22 May 2026 - 12 AM 23 May 2026 CDT

	Summary		By WFO					Watches
Type	US	IA	ARX	DVN	DMX	OAX	FSD	US
Tornado	16	2	0	0	0	1	1	0
Svr Tstorm	126	0	0	0	0	0	0	1
Flash Flood	24	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: 139 Verified:  30 [21.6%]
Polygon Size Versus County Size            [28.0%]
Average Perimeter Ratio                    [24.9%]
Percentage of Warned Area Verified (15km)  [9.2%]
Average Storm Based Warning Size           [1518 sq km]
Probability of Detection(higher is better) [0.72]
False Alarm Ratio (lower is better)        [0.78]
Critical Success Index (higher is better)  [0.20]

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