IEM Daily Bulletin for Jun 10 2026

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 10 June 2026

News

No news is good news

IEM Code Pushes <repo,branch> on Github

Timestamp	Repository	Message	Link
Jun 9 10:53 PM	iem,main	🎨 Service cleanups and sundry fixes	Link
Jun 9 11:12 PM	iem,main	💚 Address codereview and fixup!	Link
Jun 9 1:48 PM	pyiem,main	🐛 Update now-defunct go.usa URL to NHC direct	Link

Daily Feature

Jump to first 100+°F
Date: 09 Jun 05:30 AM
Votes: Good: 14   Bad: 1 Abstain: 0

So far this warm season, Iowa has mostly avoided oppressive levels of humidity coincident with the numerous days of abnormally warm temperatures. The lack of humidity has been the subject of recent IEM features regarding low dew points during much of May. This lack of humidity has kept heat index values in check with the year to date maximum for Des Moines being about 90°F this past Saturday. The forecast for today has the first real muggy heat of the season arriving with heat index values expected to exceed 100°F for much of the state. This would represent a ten degree jump in year to date maximum heat index value and that jump is the subject of today's IEM feature info-graphic. Based on unofficial hourly archives, the table presents the largest jump in heat index for the first 100+°F heat index of the year. If the forecast for Tuesday works out, it would be the third largest jump on record since about the early 1930s.

Update: Based on the hourly reports, Des Moines topped out at a heat index of 96°F. So this featured jump did not materialize!

NWS Watch/Warning Summary for 12 AM 9 Jun 2026 - 12 AM 10 Jun 2026 CDT

	Summary		By WFO					Watches
Type	US	IA	ARX	DVN	DMX	OAX	FSD	US
Tornado	16	0	0	0	0	0	0	3
Svr Tstorm	180	0	0	0	0	5	5	3
Flash Flood	31	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: 187 Verified:  88 [47.1%]
Polygon Size Versus County Size            [31.7%]
Average Perimeter Ratio                    [31.2%]
Percentage of Warned Area Verified (15km)  [20.5%]
Average Storm Based Warning Size           [2431 sq km]
Probability of Detection(higher is better) [0.82]
False Alarm Ratio (lower is better)        [0.53]
Critical Success Index (higher is better)  [0.43]

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