IEM Daily Bulletin for Jun 26 2026

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 26 June 2026

News

No news is good news

IEM Code Pushes <repo,branch> on Github

Timestamp	Repository	Message	Link
Jun 25 4:15 PM	iem,main	✨ Add phenomena,signficance filter to VTEC by UGC https://mesonet.agron.iastate.edu/json/vtec_events_byugc.py?help	Link
Jun 25 4:16 PM	iem,main	⬆️ Update ruff precommit	Link

Daily Feature

Story of 2026 So Far
Date: 25 Jun 05:30 AM
Votes: Good: 9   Bad: 0 Abstain: 1

With less than a week to go in June, it is a good time to check in how the growing season is going at about near the half way point. The featured chart presents accumulated growing degree days, precipitation, and stress degree days for the ISU Soil Moisture station just west of Ames for this year and last. Each both presents the accumulated climatology based on longer term NWS COOP data. The chart nicely tells the story for 2026 that has been mostly common for the entire state. We are in good shape with growing degree day accumulations, but have recently been loosing a bit of ground with the cooler overnight temperatures. Precipitation remains a bit below average, but nothing too dry. And stress degree days remain well below average, which helps to mitigate impacts from below average precipitation. The story of 2026 does look to change next week with much warmer temperatures and increased humidity.

The featured media can be generated on-demand here

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NWS Watch/Warning Summary for 12 AM 25 Jun 2026 - 12 AM 26 Jun 2026 CDT

	Summary		By WFO					Watches
Type	US	IA	ARX	DVN	DMX	OAX	FSD	US
Tornado	14	0	0	0	0	0	0	1
Svr Tstorm	183	0	0	0	0	0	0	5
Flash Flood	55	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: 196 Verified:  67 [34.2%]
Polygon Size Versus County Size            [19.3%]
Average Perimeter Ratio                    [24.2%]
Percentage of Warned Area Verified (15km)  [11.9%]
Average Storm Based Warning Size           [1908 sq km]
Probability of Detection(higher is better) [0.76]
False Alarm Ratio (lower is better)        [0.66]
Critical Success Index (higher is better)  [0.31]

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