Right now
The most recent data we hold from NOAA arrived 67 minutes ago, and this point is not in it. We record detections, not passes: an absence is not proof that nothing is there.
Nothing else has been detected within 20 km in the last 24 hours.
This alert expired on 1 June 2026 at 01:45 UTC. It is kept here as a record.
It is the 4th strongest of the 36 detections recorded within 20 km of this point since 31 May 2026. Another comparable one was recorded here earlier the same day. 3 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Flash Flood Warning issued May 31 at 5:51PM CDT until May 31 at 8:45PM CDT by NWS Sioux Falls SD
An estimated 15,669 people live within 50 km of this point.
Nearby, since 31 May 2026
- June 1, 2026 · score 40 · 2.4 km
- May 31, 2026 · score 58 · 14.7 km
How we know
Confirmed by 10 independent sources, including NOAA.
Our own score for this event is 40 out of 100, at 90 % confidence.
The score is ours, computed from intensity, exposed population and local history — not the source’s.
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) | 40 / 100 |
| Our confidence | 90% |
| Coordinates | 43.6183, -97.6450 |
| Nearest City | Mitchell (33 km) |
| Population Exposed | 15.7K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-05-31T22:51:00.000Z |
| Source | https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.90039340d451ce1bb40d0c7601533aa04c989093.001.1 |
Score Breakdown
Technical Details
| Event | Flash Flood Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Hanson, SD; Hutchinson, SD; McCook, SD |
| Headline | Flash Flood Warning issued May 31 at 5:51PM CDT until May 31 at 8:45PM CDT by NWS Sioux Falls SD |
| Expires | 2026-05-31T20:45:00-05:00 |
| SenderName | NWS Sioux Falls SD |
| HasExactCoords | true |
| Spc ReportType | hail |
| Spc Speed | 100 |
| Spc Location | 1 WSW Emery |
| Spc County | Hanson |
| Spc State | SD |
| Spc Comments | Very heavy rain along with penny to quarter sized hail. Rainfall is already over 3 inches. (FSD) |
| Iem TypeSummary | T |
| Iem City | 1 NW Bridgewater |
| Iem County | McCook |
| Iem State | SD |
| Iem Wfo | FSD |
| Iem Remark | Tornado is kicking up dust from the ground now. |
Safety Information
During flooding: never walk, swim, or drive through floodwaters. Six inches of moving water can knock you down, and one foot of water can sweep away a vehicle. Move to higher ground if waters rise. After flooding, avoid contact with floodwater which may contain sewage, chemicals, or debris. Follow local emergency service guidance.
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.
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