IEM Daily Bulletin for Apr 29 2026

[daryl herzmann]

Iowa Environmental Mesonet Daily Bulletin for 29 April 2026

News

No news is good news

IEM Code Pushes <repo,branch> on Github

Timestamp	Repository	Message	Link
Apr 28 9:06 AM	iem,main	📝 Document /vendor provision	Link
Apr 28 11:36 AM	iem,main	📝 Sundry updates per review	Link
Apr 28 11:44 AM	iem,main	🎨 Reduce email noise on HRRR download	Link
Apr 28 11:58 AM	iem,main	💚 Address codereview nits	Link
Apr 28 1:26 PM	iem,main	🐛 Fix columns out of order	Link
Apr 28 1:41 PM	iem,main	🐛 Fix lat/lon as optional in radar metadata service	Link
Apr 28 4:55 PM	iem,main	🎨 Improve docs and coverage of radar meta API https://mesonet.agron.iastate.edu/json/radar.py?help	Link
Apr 28 6:39 PM	iem,main	✨ Improve marker drag interaction on olselect	Link
Apr 28 7:09 PM	iem,main	📝 Sundry updates from passive review	Link
Apr 28 7:20 PM	iem,main	💚 Address codereview nits	Link
Apr 28 7:26 PM	iem,main	🐛 Replace racy os.chdir usage	Link
Apr 28 10:24 AM	pyiem,main	🎨 Preflight db check of MOS ingest with known cols	Link
Apr 28 11:07 AM	pyiem,main	✅ Complete mos test coverage	Link
Apr 28 11:15 AM	pyiem,main	💚 Address codereview nits	Link
Apr 28 11:26 AM	pyiem,main	🎨 Address bootstrap of column names	Link
Apr 28 1:29 PM	iemone,main	feat: add NWS Single RADAR (RIDGE) layer implementation - New ridgeRadarLayer.js module with tile+stations layers, metadata fetching, scan management, realtime refresh and animation support - State: RIDGE_RADAR and RIDGE_PRODUCT keys with localStorage persistence - HTML: RIDGE layer section with RADAR/product selects and scan info - layerControls.js: wires RIDGE checkbox, selects, and callbacks - main.js: initializes RIDGE layers - urlHandler.js: persists ridge_radar and ridge_product in URL - initialState.js: applies RIDGE params from localStorage fallback - timeInputControl.js: animation uses scan list when RIDGE is active - brandingOverlay.js: shows RIDGE RADAR/product/scan time when active - tests/ridgeRadarLayer.test.js: basic module tests Agent-Logs-Url: https://github.com/akrherz/iemone/sessions/08b4459e-c0ed-4949-aa5f-bd95579f3712 Co-authored-by: akrherz <210858+...@users.noreply.github.com>	Link
Apr 28 1:31 PM	iemone,main	test: expand ridgeRadarLayer tests with buildTileUrl and findClosestScan coverage Agent-Logs-Url: https://github.com/akrherz/iemone/sessions/08b4459e-c0ed-4949-aa5f-bd95579f3712 Co-authored-by: akrherz <210858+...@users.noreply.github.com>	Link
Apr 28 1:58 PM	iemone,main	🚧 Iterate on functionality, squash bugs	Link
Apr 28 2:03 PM	iemone,main	💚 Address eslint	Link
Apr 28 10:34 AM	iem-database,main	⬆️ Update ruff pre-commit	Link
Apr 28 10:34 AM	iem-database,main	✨ Add WBG storage for NBMv5 MOS refs akrherz/pyIEM#1177	Link
Apr 28 9:13 AM	iem-web-services,main	⬆️ Update ruff pre-commit	Link
Apr 28 9:41 AM	iem-web-services,main	⚡️ Restrict call parameters to currents API	Link
Apr 28 9:43 AM	iem-web-services,main	🔥 Drop unused and ill-formed events from currents	Link
Apr 28 9:48 AM	iem-web-services,main	💚 Address codereview need for classmethod	Link
Apr 28 9:54 AM	iem-web-services,main	💚 Address codereview nits	Link
Apr 28 10:01 AM	iem-web-services,main	💚 Address codereview nit on validation	Link
Apr 28 7:37 PM	iem-web-services,main	⚡️ Convert bufkit service to async Attempt to prevent upstream slowness from over-running API workers.	Link
Apr 28 8:02 PM	iem-web-services,main	💚 Address codereview nits	Link

Daily Feature

Record Day for NWS St Louis
Date: 28 Apr 05:30 AM
Votes: Good: 12   Bad: 0 Abstain: 0

While the severe weather threat on Monday mostly missed Iowa, nearby states were not as fortunate. NWS St Louis had an extremely busy day with severe weather persisting throughout much of the day. Based on unofficial IEM data, the office issued the most combined Severe Thunderstorm + Tornado + Flash Flood Warnings for a calendar day since at least 1986. The 95 warnings were 15 more than the previous day max on 25 May 2011. Thankfully, a break from the severe weather and heavy rainfall events is currently forecast for the remainder of the week. The only downside will be cool temperatures, which will not be of much help for crops already planted this growing season.

The featured media can be generated on-demand here

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NWS Watch/Warning Summary for 12 AM 28 Apr 2026 - 12 AM 29 Apr 2026 CDT

	Summary		By WFO					Watches
Type	US	IA	ARX	DVN	DMX	OAX	FSD	US
Tornado	54	0	0	0	0	0	0	7
Svr Tstorm	278	0	0	0	0	0	0	5
Flash Flood	11	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: 323 Verified: 138 [42.7%]
Polygon Size Versus County Size            [33.9%]
Average Perimeter Ratio                    [29.2%]
Percentage of Warned Area Verified (15km)  [18.1%]
Average Storm Based Warning Size           [1945 sq km]
Probability of Detection(higher is better) [0.85]
False Alarm Ratio (lower is better)        [0.57]
Critical Success Index (higher is better)  [0.40]

IEMBot Social Media Posts

IEMBot can be configured to post messages to a number of social media services. More details: IEMBot Homepage.

Posts yesterday per supported service:

• ATMosphere (bluesky only attm): 2,180
• Mastodon / Fediverse: 30
• Slack: 224
• Twitter/X: 23,718
• HTTP Webhooks: 503
• Weather.IM Jabber Chatrooms: 18,970