IEM Daily Bulletin for Jul 5 2026

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 05 July 2026

News

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Timestamp	Repository	Message	Link
Jul 5 5:05 AM	iem-web-services,main	⬆️ Update ruff precommit	Link

Daily Feature

Northern Polk/Southern Story Deluge
Date: 04 Jul 12:01 AM
Votes: Good: 21   Bad: 0 Abstain: 0

The abundant heat and humidity this week continues to fuel daily thunderstorm complexes that are prolific heavy rainfall producers. One such complex produced incredible rainfall totals over northern Polk (northern Des Moines suburbs) and southern Story counties. The featured map combines NOAA MRMS 24 hour rainfall total estimates derived mostly from RADAR with observed values from CoCoRaHS, NWS COOP, and NWS Local Storm Reports. There is some timing ambiguity between these datasets with the MRMS totals ending at 10 AM 3 July and some of the morning CoCoRaHS/COOP reports not including a bit of additional rainfall after around approximately 7 AM. Additionally, more precipitation fell during the Friday afternoon hours and into Saturday morning, so it is not easy to produce an isolated storm total from these CoCoRaHS reports. NWS Des Moines got a public report of 12.60" near Elkhart (NE of Ankeny/Des Moines), which is not much lower than the official Iowa 24 hour precipitation record of 13.18" back on 13-14 Jun 1998 at Atlantic. This featured deluge is also only a few days removed from a historic rainfall back on 30 Jun 2018 that occurred over approximately the same area.

NWS Watch/Warning Summary for 12 AM 4 Jul 2026 - 12 AM 5 Jul 2026 CDT

	Summary		By WFO					Watches
Type	US	IA	ARX	DVN	DMX	OAX	FSD	US
Tornado	4	0	0	0	0	0	0	0
Svr Tstorm	494	8	0	2	6	1	0	10
Flash Flood	48	4	0	1	4	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: 493 Verified: 298 [60.4%]
Polygon Size Versus County Size            [28.8%]
Average Perimeter Ratio                    [28.8%]
Percentage of Warned Area Verified (15km)  [31.6%]
Average Storm Based Warning Size           [1610 sq km]
Probability of Detection(higher is better) [0.86]
False Alarm Ratio (lower is better)        [0.40]
Critical Success Index (higher is better)  [0.55]

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