IEM Daily Bulletin for Aug 4 2026

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 04 August 2026

News

No news is good news

IEM Code Pushes <repo,branch> on Github

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Daily Feature

Before and After 1 August
Date: 03 Aug 05:30 AM
Votes: Good: 10   Bad: 7 Abstain: 1

With the calendar now turned into August, we have fully reached the last half of the warmest part of the year. Average high temperatures have been slightly above average for the June through July period. The featured chart looks into if this portends what may happen during the August through September period. The chart presents the yearly combination of average high temperature for Ames for the sixty days prior to and after 1 August. Of note for this plot are the quadrant frequencies, which indicate a persistence to having both periods either below average or above average each year.

The featured media can be generated on-demand here

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

	Summary		By WFO					Watches
Type	US	IA	ARX	DVN	DMX	OAX	FSD	US
Tornado	2	0	0	0	0	0	0	0
Svr Tstorm	48	0	0	0	0	0	0	1
Flash Flood	29	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:  48 Verified:  12 [25.0%]
Polygon Size Versus County Size            [8.1%]
Average Perimeter Ratio                    [18.2%]
Percentage of Warned Area Verified (15km)  [12.7%]
Average Storm Based Warning Size           [1275 sq km]
Probability of Detection(higher is better) [0.57]
False Alarm Ratio (lower is better)        [0.75]
Critical Success Index (higher is better)  [0.21]

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