Right now
The most recent data we hold from NOAA arrived 4 minutes ago, and this point is not in it. We record detections, not passes: an absence is not proof that nothing is there.
This alert expired on 21 July 2026 at 03:00 UTC. It is kept here as a record.
What the source measured
NOAA reported: Tornado Watch issued July 20 at 8:43PM CDT until July 20 at 10:00PM CDT by NWS Des Moines IA
Urban PEI: 181,553 within a heuristic 50 km radius; not unique people.
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 55 out of 100.
This is our versioned heuristic index, not source severity or a calibrated probability. Urban PEI does not count unique people.
Computed under scoring rules v1. Rows carrying other versions were judged by different rules and are not directly comparable.
Event Data
| Type | Severe Weather |
| Severity | Medium |
| Calamity Score (ours) | 55 / 100 |
| Legacy data-support index | 0.80/1 |
| Coordinates | 42.0000, -93.2000 |
| Nearest City | Marshalltown (25 km) |
| Urban exposure index (PEI) | 181.6K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-07-21T01:43:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Tornado Watch_noaa_urn:oid:2.49.0.1.840.0.dbac8bacadbb27bf22aef07808a7a324 |
Physical priority index · v1. Heuristic priority, not calibrated probability, predictive accuracy or damage. The legacy data-support index combines assigned source support and field availability. Urban PEI is distance-weighted and does not count unique people; zero does not establish that nobody is present. Model cards.
Source and revision timeline
Source: noaa. Occurrence: 2026-07-21T01:43:00.000Z.
First archived: 2026-07-21T01:50:50.457Z. Material modification: not recorded.
Retained revisions are prospective; earlier versions may be unavailable. No revision entry does not prove that a record never changed.
Score Breakdown
Technical Details
| Event | Tornado Watch |
| Urgency | Future |
| Certainty | Possible |
| AreaDesc | Adair, IA; Appanoose, IA; Boone, IA; Dallas, IA; Davis, IA; Greene, IA; Guthrie, IA; Jasper, IA; Lucas, IA; Madison, IA; Mahaska, IA; Marion, IA; Marshall, IA; Monroe, IA; Polk, IA; Poweshiek, IA; Story, IA; Wapello, IA; Warren, IA; Wayne, IA; Des Moines, IA; Henry, IA; Jefferson, IA; Keokuk, IA; Lee, IA; Louisa, IA; Van Buren, IA; Washington, IA |
| Headline | Tornado Watch issued July 20 at 8:43PM CDT until July 20 at 10:00PM CDT by NWS Des Moines IA |
| Expires | 2026-07-20T22:00:00-05:00 |
| SenderName | NWS Des Moines IA |
| HasExactCoords | false |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.dbac8bacadbb27bf22aef07808a7a324187d9cba.002.1","noaa_urn:oid:2.49.0.1.840.0.5c699ce5adce941fbce403c2d465f4154d465f9e.003.1"] |
Safety Information
If a tornado warning is issued: go to a basement or an interior room on the lowest floor, away from windows. A vehicle and a mobile home are not shelter. Cover your head and neck. Wait for the official all-clear before going outside, and watch for downed power lines and gas leaks afterwards.
Series begins 8 March 2026. Comparisons refer to that period only. Collection gap: 14-26 August 2026.
This data is aggregated algorithmically from scientific sources. Not a replacement for official emergency warnings.
Review the area, threshold and delivery channel in your account.
Want to know when something happens near Marshalltown?