IEM Daily Bulletin for Jul 4 2026

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 04 July 2026

News

No news is good news

IEM Code Pushes <repo,branch> on Github

Timestamp	Repository	Message	Link
Jul 4 5:46 AM	pyiem,main	✨ Add alpha as kwarg to pcolormesh	Link
Jul 4 5:46 AM	pyiem,main	⬆️ Update precommits	Link

Daily Feature

Cedar Rapids July Dew Points
Date: 03 Jul 05:30 AM
Votes: Good: 9   Bad: 0 Abstain: 0

Slow moving storms and associated clouds on Thursday helped to isolate the most extreme heat index values to southeastern Iowa with places like Cedar Rapids briefly reaching the triple digits. The featured chart looks into the dew point climatology by air temperature during the month of July for Cedar Rapids. The chart nicely shows a fortunate feature of Iowa's summer time dew point temperatures with decreasing values found with the most extreme air temperatures. The reason why has to do with surface energy budgets and the requirement of more input energy to heat a higher water content air. It is also a sort of self fulfilling prophesy that drier air is able to more quickly heat and mix down warmer air aloft, so air temperatures can reach higher temperatures. The climatology plotted shows a bit of an inflection point near 95°F as the average dew point values start to decrease.

The featured media can be generated on-demand here

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NWS Watch/Warning Summary for 12 AM 3 Jul 2026 - 12 AM 4 Jul 2026 CDT

	Summary		By WFO					Watches
Type	US	IA	ARX	DVN	DMX	OAX	FSD	US
Tornado	12	0	0	2	0	0	0	0
Svr Tstorm	378	7	0	11	1	14	0	8
Flash Flood	36	4	0	1	2	3	2	---

ARX = LaCrosse, WI DVN = Davenport, IA DMX = Des Moines, IA OAX = Omaha, NE FSD = Sioux Falls, SD

IEM Cow Report

SVR+TOR Warnings Issued: 387 Verified: 227 [58.7%]
Polygon Size Versus County Size            [26.1%]
Average Perimeter Ratio                    [33.9%]
Percentage of Warned Area Verified (15km)  [32.2%]
Average Storm Based Warning Size           [1311 sq km]
Probability of Detection(higher is better) [0.86]
False Alarm Ratio (lower is better)        [0.41]
Critical Success Index (higher is better)  [0.53]

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