IEM Daily Bulletin for Nov 20 2025

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 20 November 2025

News

No news is good news

IEM Code Pushes <repo,branch> on Github

Timestamp	Repository	Message	Link
Nov 19 10:09 PM	iem,main	🎨 Clarify ceiling calculation to include BRK https://mesonet.agron.iastate.edu/plotting/auto/?q=162	Link

Daily Feature

Fall Season Avg Temp
Date: 19 Nov 05:30 AM
Votes: Good: 10   Bad: 0 Abstain: 0

If you consider the fall season to include the months of September, October, and November (SON), then we just have under two weeks to go to complete the season. The featured chart presents the fall season average temperature for Ames since 1893. The 2025 value currently comes in as the warmest on record, but the remaining days of November will certainly pull this average down. The yearly values are fit with a simple linear regression, which does not show much of any correlation. It is interesting to note that last year and this year will at least be top 5 warmest.

The featured media can be generated on-demand here

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NWS Watch/Warning Summary for 12 AM 19 Nov 2025 - 12 AM 20 Nov 2025 CST

	Summary		By WFO					Watches
Type	US	IA	ARX	DVN	DMX	OAX	FSD	US
Tornado	0	0	0	0	0	0	0	0
Svr Tstorm	35	0	0	0	0	0	0	0
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:  32 Verified:   9 [28.1%]
Polygon Size Versus County Size            [11.5%]
Average Perimeter Ratio                    [17.1%]
Percentage of Warned Area Verified (15km)  [18.3%]
Average Storm Based Warning Size           [849 sq km]
Probability of Detection(higher is better) [0.83]
False Alarm Ratio (lower is better)        [0.72]
Critical Success Index (higher is better)  [0.27]