IEM Daily Bulletin for Apr 30 2026

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 30 April 2026

News

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Daily Feature

Interesting April Combo
Date: 29 Apr 05:30 AM
Votes: Good: 7   Bad: 0 Abstain: 1

The weather this April has certainly been interesting with plenty of warmth and precipitation. The featured chart compares April growing degree day departures with precipitation departures for April over a statewide areal average computed by the IEM. The departures are expressed in units of standard deviation to allow a normalized comparison between the two variables. The 2026 combination stands out for being both anomalously warm and wet, while also being counter trend which favors reduced precipitation with increasing temperature. The last two days of April will be on the cooler and drier side of average, so the 2026 will value will be pulled marginally back to the middle if you generate this plot once April completes!

The featured media can be generated on-demand here

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NWS Watch/Warning Summary for 12 AM 29 Apr 2026 - 12 AM 30 Apr 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	101	0	0	0	0	0	0	3
Flash Flood	3	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: 103 Verified:  53 [51.5%]
Polygon Size Versus County Size            [30.1%]
Average Perimeter Ratio                    [27.5%]
Percentage of Warned Area Verified (15km)  [19.5%]
Average Storm Based Warning Size           [1903 sq km]
Probability of Detection(higher is better) [0.88]
False Alarm Ratio (lower is better)        [0.49]
Critical Success Index (higher is better)  [0.48]

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