IEM Daily Bulletin for May 7 2026

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 07 May 2026

News

No news is good news

IEM Code Pushes <repo,branch> on Github

Timestamp	Repository	Message	Link
May 6 2:15 PM	iem,main	⚡️ Generalize caching logic	Link
May 6 2:21 PM	iem,main	💚 Address codereview to prevent KeyError	Link
May 6 3:00 PM	iem,main	🐛 Address cache key	Link
May 6 3:48 PM	iem,main	🔥 Drop unused caching logic	Link
May 6 9:48 PM	iem,main	🎨 Catch and instrument NUL bytes issue	Link

Daily Feature

May Sub-60°F High
Date: 06 May 05:30 AM
Votes: Good: 13   Bad: 1 Abstain: 1

For Des Moines, the high temperature on Tuesday was just 59°F. The rest of the state did not fare much better with most below 60°F for the day. The featured chart presents the day of May frequency of having a high temperature below 60°F for Des Moines. The overall frequency for a single May is about 3.5 days, so these events are not terribly rare. The chart does nicely show the near linear decline in frequency as the month progresses, but another repeat looks to be in store today before warmer weather returns starting Thursday.

The featured media can be generated on-demand here

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NWS Watch/Warning Summary for 12 AM 6 May 2026 - 12 AM 7 May 2026 CDT

	Summary		By WFO					Watches
Type	US	IA	ARX	DVN	DMX	OAX	FSD	US
Tornado	21	0	0	0	0	0	0	4
Svr Tstorm	61	0	0	0	0	0	0	1
Flash Flood	14	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:  80 Verified:  31 [38.8%]
Polygon Size Versus County Size            [30.8%]
Average Perimeter Ratio                    [34.1%]
Percentage of Warned Area Verified (15km)  [19.7%]
Average Storm Based Warning Size           [1665 sq km]
Probability of Detection(higher is better) [0.92]
False Alarm Ratio (lower is better)        [0.61]
Critical Success Index (higher is better)  [0.38]

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