Right now
The most recent data we hold from NOAA arrived 22 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 20 June 2026 at 01:15 UTC. It is kept here as a record.
It is the 4th strongest of the 40 detections recorded within 20 km of this point since 15 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: Severe Thunderstorm Warning issued June 19 at 7:42PM CDT until June 19 at 8:15PM CDT by NWS La Crosse WI
Urban PEI: 84,083 within a heuristic 50 km radius; not unique people.
Nearby, since 15 March 2026
- June 20, 2026 · score 39 · 6.3 km
How we know
7 recorded sources include NOAA; independence is not established by this count.
Our own score for this event is 39 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) | 39 / 100 |
| Legacy data-support index | 0.90/1 |
| Coordinates | 44.5087, -91.5755 |
| Nearest City | Eau Claire (34 km) |
| Urban exposure index (PEI) | 84.1K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-06-20T00:42:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Severe Thunderstorm Warning_noaa_urn:oid:2.49.0.1.840.0.b737300b5b5b333c974b7ff8d098a46d |
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: 2026-06-20T00:42:00.000Z.
First archived: 2026-06-20T00:48:55.648Z. 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 | Trempealeau, WI; Buffalo, WI |
| Headline | Severe Thunderstorm Warning issued June 19 at 7:42PM CDT until June 19 at 8:15PM CDT by NWS La Crosse WI |
| Expires | 2026-06-19T20:15:00-05:00 |
| SenderName | NWS La Crosse WI |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.b737300b5b5b333c974b7ff8d098a46dd2913ec7.001.1","noaa_urn:oid:2.49.0.1.840.0.1e6e417385253ed8c74d9bb29a8a685ee1e0aeec.001.1"] |
| Iem TypeSummary | H |
| Iem Magnitude | 1 |
| Iem Unit | Inch |
| Iem City | 2 ENE Osseo |
| Iem County | Trempealeau |
| Iem State | WI |
| Iem Wfo | ARX |
| Iem Remark | Report of quarter sized hail east of Osseo. |
| MergedSources | [{"id":"iem_D_45.040_-92.040_1781913180000","source":"iem","severity":"low","severityValue":25,"timestamp":1781913180000,"latitude":45.04,"longitude":-92.04},{"id":"iem_D_44.980_-91.930_1781913300000","source":"iem","severity":"low","severityValue":25,"timestamp":1781913300000,"latitude":44.98,"longitude":-91.93},{"id":"iem_C_44.610_-91.190_1781913180000","source":"iem","severity":"low","severityValue":25,"timestamp":1781913180000,"latitude":44.61,"longitude":-91.19},{"id":"iem_H_44.720_-92.440_1781911200000","source":"iem","severity":"low","severityValue":25,"timestamp":1781911200000,"latitude":44.72,"longitude":-92.44},{"id":"iem_H_44.760_-91.460_1781909640000","source":"iem","severity":"low","severityValue":25,"timestamp":1781909640000,"latitude":44.76,"longitude":-91.46},{"id":"iem_H_44.590_-91.170_1781912820000","source":"iem","severity":"low","severityValue":25,"timestamp":1781912820000,"latitude":44.59,"longitude":-91.17}] |
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.
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