IEM Daily Bulletin for Aug 6 2025

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 06 August 2025

News

No news is good news

IEM Code Pushes <repo,branch> on Github

Timestamp	Repository	Message	Link
No code commits found in previous 24 Hours

Daily Feature

Reaching 2400 GDDs
Date: 05 Aug 05:30 AM
Votes: Good: 8   Bad: 0 Abstain: 0

With the calendar now firmly within August, the fall season is not all that far away! This is about the time of year when fretting occurs for if enough heat units will be accumulated to bring crops to maturity prior to the first fall freeze. The featured chart is one such tool in this space and presents frequencies of reaching 2,400 growing degree days by the given fall date for a given start date (read planting date) for Ames. The left hand chart shows climatological values using period of record observations and the right hand chart presents probabilities using the current 2025 accumulation to 4 August and then appending all previous years onto the current year to create possible scenarios. While 2,400 units is an aggressive maturity number for Ames given the frequency drop off with late May planting dates shown by the left hand plot, this year looks in rather good shape with even late May planting dates needing to make it into the third week of September to reach maturity. Of course, things aren't generally this simple for a crop reaching maturity and the freezing date cut-off of only breaching 32 degrees is likely too restrictive as well, but the plot tells an informative story.

The featured media can be generated on-demand here

.

NWS Watch/Warning Summary for 12 AM 5 Aug 2025 - 12 AM 6 Aug 2025 CDT

	Summary		By WFO					Watches
Type	US	IA	ARX	DVN	DMX	OAX	FSD	US
Tornado	7	0	0	0	0	0	0	1
Svr Tstorm	65	0	0	0	0	0	6	0
Flash Flood	21	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:  64 Verified:  13 [20.3%]
Polygon Size Versus County Size            [20.5%]
Average Perimeter Ratio                    [25.1%]
Percentage of Warned Area Verified (15km)  [8.9%]
Average Storm Based Warning Size           [1400 sq km]
Probability of Detection(higher is better) [0.45]
False Alarm Ratio (lower is better)        [0.80]
Critical Success Index (higher is better)  [0.16]