IEM Daily Bulletin for Jul 4 2025

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 04 July 2025

News

No news is good news

IEM Code Pushes <repo,branch> on Github

Timestamp	Repository	Message	Link
Jul 3 9:41 AM	iem,main	🐛 Revert jsani change	Link
Jul 3 7:50 AM	pywwa,main	⬆️ Update ruff	Link
Jul 3 7:50 AM	pywwa,main	📝 More pireps	Link

Daily Feature

Hourly Wind Speed Climo
Date: 03 Jul 05:30 AM
Votes: Good: 7   Bad: 0 Abstain: 0

The featured chart presents a simple hourly wind speed climatology for Ames by month. The summer months of July and August generally have the slowest wind speeds with April and March having the strongest. Near surface wind speeds are driven by horizontal pressure gradients, which are the weakest during the aforementioned months. The chart also nicely shows the diurnal cycle with solar heating of the ground and then the air causing the lower atmosphere to vertically mix, which transports momentum aloft to the surface.

The featured media can be generated on-demand here

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NWS Watch/Warning Summary for 12 AM 3 Jul 2025 - 12 AM 4 Jul 2025 CDT

	Summary		By WFO					Watches
Type	US	IA	ARX	DVN	DMX	OAX	FSD	US
Tornado	1	0	0	0	0	0	0	0
Svr Tstorm	142	3	5	2	1	0	1	3
Flash Flood	38	2	2	1	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: 141 Verified:  69 [48.9%]
Polygon Size Versus County Size            [12.6%]
Average Perimeter Ratio                    [19.1%]
Percentage of Warned Area Verified (15km)  [27.7%]
Average Storm Based Warning Size           [1279 sq km]
Probability of Detection(higher is better) [0.81]
False Alarm Ratio (lower is better)        [0.51]
Critical Success Index (higher is better)  [0.44]