Right now
The most recent data we hold from NOAA arrived 40 minutes ago, and this point is not in it. We record detections, not passes: an absence is not proof that nothing is there.
8 other detections within 20 km in the last 24 hours, the nearest <1 km from here.
This alert expired on 17 May 2026 at 04:00 UTC. It is kept here as a record.
It is the 7th strongest of the 254 detections recorded within 20 km of this point since 10 March 2026. Another comparable one was recorded here earlier the same day. 9 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Tornado Watch issued May 16 at 4:43PM CDT until May 16 at 11:00PM CDT by NWS Des Moines IA
Urban PEI: 181,553 within a heuristic 50 km radius; not unique people.
Nearby, since 10 March 2026
- September 15, 2026 · score 55 · 0.0 km
- September 14, 2026 · score 55 · 0.0 km
- September 6, 2026 · score 37 · 0.0 km
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 | High |
| Calamity Score (ours) | 55 / 100 |
| Legacy data-support index | 0.79/1 |
| Coordinates | 42.0000, -93.2000 |
| Nearest City | Marshalltown (25 km) |
| Urban exposure index (PEI) | 181.6K within 50 km |
| Impact Tier | severe |
| Timestamp | 2026-05-16T21:43:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Tornado Watch_noaa_urn:oid:2.49.0.1.840.0.84a6eea6887565cfdea7535d05e02af2 |
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: 2026-05-16T21:43:00.000Z.
First archived: 2026-05-16T22:07:44.263Z. 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; Adams, IA; Appanoose, IA; Cass, IA; Clarke, IA; Decatur, IA; Lucas, IA; Madison, IA; Ringgold, IA; Taylor, IA; Union, IA; Warren, IA; Wayne, IA; Fremont, IA; Mills, IA; Montgomery, IA; Page, IA |
| Headline | Tornado Watch issued May 16 at 4:43PM CDT until May 16 at 11:00PM CDT by NWS Des Moines IA |
| Expires | 2026-05-16T23:00:00-05:00 |
| SenderName | NWS Des Moines IA |
| HasExactCoords | false |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.84a6eea6887565cfdea7535d05e02af21e1fb6af.001.1","noaa_urn:oid:2.49.0.1.840.0.00f88657f04e6437eb4e3c9cb27028276ef3e9c9.001.1"] |
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.
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