Right now
The most recent data we hold from NOAA arrived 15 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 17 May 2026 at 21:15 UTC. It is kept here as a record.
It is the 7th strongest of the 48 detections recorded within 20 km of this point since 17 May 2026. Another comparable one was recorded here earlier the same day. 6 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued May 17 at 3:37PM CDT until May 17 at 4:15PM CDT by NWS Sioux Falls SD
How we know
13 recorded sources include NOAA; independence is not established by this count.
Our own score for this event is 22 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) | 22 / 100 |
| Legacy data-support index | 0.69/1 |
| Coordinates | 43.1280, -97.4180 |
| Nearest City | Sioux Falls (72 km) |
| Urban exposure index (PEI) | 0 within 50 km |
| Impact Tier | minor |
| Timestamp | 2026-05-17T20:37:00.000Z |
| Source | https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.3628ce42a0e60dd6a598ed96acd7d7e92ab54ec7.001.1 |
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: 2026-05-17T20:37:00.000Z.
First archived: 2026-05-17T20:56:19.443Z. 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 | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Bon Homme, SD; Clay, SD; Hutchinson, SD; Turner, SD; Yankton, SD |
| Headline | Severe Thunderstorm Warning issued May 17 at 3:37PM CDT until May 17 at 4:15PM CDT by NWS Sioux Falls SD |
| Expires | 2026-05-17T16:15:00-05:00 |
| SenderName | NWS Sioux Falls SD |
| HasExactCoords | true |
| Iem TypeSummary | D |
| Iem City | 2 W Avon |
| Iem County | Bon Homme |
| Iem State | SD |
| Iem Wfo | FSD |
| Iem Remark | Trained spotter reported a shed with its roof blown off. |
| MergedSources | [{"id":"iem_G_43.070_-98.300_1779047280000","source":"iem","severity":"low","severityValue":25,"timestamp":1779047280000,"latitude":43.07,"longitude":-98.3},{"id":"iem_G_43.010_-98.000_1779047880000","source":"iem","severity":"low","severityValue":25,"timestamp":1779047880000,"latitude":43.01,"longitude":-98},{"id":"iem_D_43.160_-97.970_1779048300000","source":"iem","severity":"low","severityValue":25,"timestamp":1779048300000,"latitude":43.16,"longitude":-97.97},{"id":"iem_G_43.000_-97.970_1779048000000","source":"iem","severity":"low","severityValue":25,"timestamp":1779048000000,"latitude":43,"longitude":-97.97},{"id":"iem_D_43.070_-98.330_1779046800000","source":"iem","severity":"low","severityValue":25,"timestamp":1779046800000,"latitude":43.07,"longitude":-98.33},{"id":"iem_G_43.080_-98.130_1779047520000","source":"iem","severity":"low","severityValue":25,"timestamp":1779047520000,"latitude":43.08,"longitude":-98.13},{"id":"iem_H_43.220_-97.510_1779050640000","source":"iem","severity":"low","severityValue":25,"timestamp":1779050640000,"latitude":43.22,"longitude":-97.51},{"id":"iem_D_43.070_-98.330_1779047160000","source":"iem","severity":"low","severityValue":25,"timestamp":1779047160000,"latitude":43.07,"longitude":-98.33},{"id":"iem_G_43.070_-98.310_1779046800000","source":"iem","severity":"low","severityValue":25,"timestamp":1779046800000,"latitude":43.07,"longitude":-98.31},{"id":"iem_G_43.160_-97.760_1779048960000","source":"iem","severity":"low","severityValue":25,"timestamp":1779048960000,"latitude":43.16,"longitude":-97.76},{"id":"iem_D_43.080_-98.190_1779047400000","source":"iem","severity":"low","severityValue":25,"timestamp":1779047400000,"latitude":43.08,"longitude":-98.19},{"id":"iem_D_43.010_-98.100_1779047640000","source":"iem","severity":"low","severityValue":25,"timestamp":1779047640000,"latitude":43.01,"longitude":-98.1}] |
Safety Information
Always follow official guidance from your local emergency management agency. This platform provides scientific monitoring data and is not a substitute for official warnings. If you are in immediate danger, contact your local emergency number.
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 in this area?