IEM Daily Bulletin for Apr 21 2026

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 21 April 2026

News

No news is good news

IEM Code Pushes <repo,branch> on Github

Timestamp	Repository	Message	Link
Apr 20 8:52 AM	pyiem,main	🎨 Account for PTS edge case of reversed poly	Link
Apr 20 8:52 AM	pyiem,main	⚡️ Guard non-func codepath	Link
Apr 20 10:30 PM	pyiem,main	🎨 Prevent GIGO on some autoplot date fields	Link

Daily Feature

Last Week's Precipitation
Date: 20 Apr 05:30 AM
Votes: Good: 13   Bad: 0 Abstain: 2

With the numerous rounds of showers and thunderstorms last week, it is a good time to see how the precipitation totals fared. The featured map presents NOAA MRMS estimates for the inclusive period between 12 and 18 April 2026. The heaviest totals are shown over east central Iowa with isolated areas indicated over five inches. Much of the western half of the state missed out though with a few pockets of no-measurable precipitation shown. The stormy weather of last week gave way to a chilly weekend with Monday starting off below freezing over much of the state. Temperatures will warm as this week progresses with rain chances again returning by Thursday, but the heaviest totals again look to miss the same areas that missed out last week.

The featured media can be generated on-demand here

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NWS Watch/Warning Summary for 12 AM 20 Apr 2026 - 12 AM 21 Apr 2026 CDT

	Summary		By WFO					Watches
Type	US	IA	ARX	DVN	DMX	OAX	FSD	US
Tornado	0	0	0	0	0	0	0	0
Svr Tstorm	1	0	0	0	0	0	0	0
Flash Flood	2	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:   1 Verified:   0 [0.0%]
Polygon Size Versus County Size            [4.5%]
Average Perimeter Ratio                    [0.0%]
Percentage of Warned Area Verified (15km)  [0.0%]
Average Storm Based Warning Size           [319 sq km]
Probability of Detection(higher is better) [0.00]
False Alarm Ratio (lower is better)        [1.00]
Critical Success Index (higher is better)  [0.00]

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