IEM Daily Bulletin for Sep 27 2025
daryl herzmann
Iowa Environmental Mesonet Daily Bulletin for 27 September 2025
News
No news is good newsIEM Code Pushes <repo,branch> on Github
| Timestamp | Repository | Message | Link |
|---|---|---|---|
| Sep 26 10:14 AM | iem,main | ⬆️ Update precommits | Link |
| Sep 26 11:40 AM | iem,main | ⚡️ Improve and enhance IEMRE multiday service https://mesonet.agron.iastate.edu/iemre/multiday.py?help |
Link |
| Sep 26 11:42 AM | iem,main | 💚 Address deepsource concern | Link |
| Sep 26 11:54 AM | iem,main | 💚 Address bug found in CI | Link |
| Sep 26 10:16 AM | pyiem,main | ⬆️ Update ruff | Link |
| Sep 26 2:05 PM | pyiem,main | 🐛 [taf] Fix parse logic error when no = | Link |
| Sep 26 9:48 AM | pywwa,main | 📝 Update archive location per akrherz/infra#7 | Link |
| Sep 26 9:48 AM | pywwa,main | ⬆️ Update ruff | Link |
| Sep 26 10:09 AM | pywwa,main | 🚚 Change archive location per akrherz/infra#7 | Link |
| Sep 26 10:13 PM | iem-web-services,main | 🐛 Use source to remove ambiguity in nwstext | Link |
| Sep 26 10:14 PM | iem-web-services,main | 🚚 Correct pyiem get_dbconn import | Link |
| Sep 26 10:14 PM | iem-web-services,main | ⬆️ Update ruff | Link |
Daily Feature
Contiguous US Drought Changes
Date: 26 Sep 05:30 AM
Votes: Good: 7
Bad: 0 Abstain: 0
The featured chart presents an IEM visualization attempt to show net weekly changes in the US Drought Monitor since 2010. The weekly data is smoothed with red areas indicating net deterioration and blue being improvements. The recent trend for 2025 has been for deterioration after improvements during the spring season. The drought of 2012 is nicely shown on this chart with the large red area appearing during June and July. The unit height of the waves represents a one category change over a contiguous US area of size. The lack of land-falling Hurricanes this season has certainly not helped the worsening drought over the southeastern US.
The featured media can be generated on-demand here
.NWS Watch/Warning Summary for 12 AM 26 Sep 2025 - 12 AM 27 Sep 2025 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 | 38 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| Flash Flood | 23 | 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: 38 Verified: 9 [23.7%] Polygon Size Versus County Size [4.6%] Average Perimeter Ratio [4.3%] Percentage of Warned Area Verified (15km) [13.9%] Average Storm Based Warning Size [1169 sq km] Probability of Detection(higher is better) [0.68] False Alarm Ratio (lower is better) [0.76] Critical Success Index (higher is better) [0.21]