IEM Daily Bulletin for Mar 14 2026

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 14 March 2026

News

No news is good news

IEM Code Pushes <repo,branch> on Github

Timestamp	Repository	Message	Link
Mar 13 11:08 AM	iem,main	📝 Remove invalid link	Link
Mar 12 7:43 PM	iem,main	🥅 Prevent a wind speed GIGO in MADIS ingest	Link
Mar 13 12:57 PM	iem,main	✏️ Fix link	Link
Mar 13 4:48 PM	iem,main	🎨 Mess with AFOS METAR life choices https://mesonet.agron.iastate.edu/cgi-bin/afos/retrieve.py?help Ask for 1, get the latest non MADISHF. Ask for more than 1, get anything available.	Link
Mar 13 4:50 PM	iem,main	⬆️ Update ruff	Link
Mar 13 4:05 PM	iem-database,main	⬆️ Update ruff precommit	Link
Mar 13 4:07 PM	iem-database,main	✨ Add attrs to iembot_slack_teams	Link

Daily Feature

180 Day Aridity Index
Date: 13 Mar 05:30 AM
Votes: Good: 9   Bad: 0 Abstain: 0

There are many different aridity indices attempting to express how anomalous precipitation and temperatures are. One such index formulation is the subject of today's IEM daily feature. This index is computed by taking the standardized departure of average high temperature and subtracting the standardized precipitation departure over trailing 180 day windows of time. The standardization is done by dividing the actual departure by the standard deviation value, which creates a unit-less value that be used to lump the temperature and precipitation values together. Of course, no index is perfect, but some are useful. Anyway, values that are more positive are indicative of periods of water availability stress (warmer air temperatures and low precipitation totals). The trick is to realize that the precipitation departure is being subtracted in the equation, so negative precipitation departures increase the index value. What is interesting about the plot showing data for Ames since 2012 is that current values are some of the most positive shown and starting to be comparable to those during the drought of 2012. The drought situation is not urgent yet as the growing season has yet to start, but increases in precipitation would certainly help to improve drought indices like the one shown here.

The featured media can be generated on-demand here

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NWS Watch/Warning Summary for 12 AM 13 Mar 2026 - 12 AM 14 Mar 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	5	0	0	0	0	0	0	0
Flash Flood	4	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:   5 Verified:   4 [80.0%]
Polygon Size Versus County Size            [56.7%]
Average Perimeter Ratio                    [57.4%]
Percentage of Warned Area Verified (15km)  [20.3%]
Average Storm Based Warning Size           [4722 sq km]
Probability of Detection(higher is better) [1.00]
False Alarm Ratio (lower is better)        [0.20]
Critical Success Index (higher is better)  [0.80]

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