Right now
The most recent data we hold from NOAA arrived 2 minutes ago, and this point is not in it. We record detections, not passes: an absence is not proof that nothing is there.
3 other detections within 20 km in the last 24 hours, the nearest <1 km from here.
This alert expired on 18 September 2026 at 21:02 UTC. It is kept here as a record.
It is the 13th strongest of the 21 detections recorded within 20 km of this point since 13 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 September 18 at 2:52PM MDT until September 18 at 3:00PM MDT by NWS Salt Lake City UT
Urban PEI: 426,098 within a heuristic 50 km radius; not unique people.
Nearby, since 13 May 2026
- September 18, 2026 · score 37 · 5.0 km
- May 13, 2026 · score 43 · 11.8 km
- August 29, 2026 · score 48 · 15.1 km
How we know
2 recorded sources include NOAA; independence is not established by this count.
Our own score for this event is 37 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 v5. Rows carrying other versions were judged by different rules and are not directly comparable.
Event Data
| Type | Severe Weather |
| Severity | Medium |
| Calamity Score (ours) | 37 / 100 |
| Legacy data-support index | 0.85/1 |
| Coordinates | 41.2242, -111.5417 |
| Nearest City | Ogden (36 km) |
| Urban exposure index (PEI) | 426.1K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-09-18T20:52:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.1ab72d725fdef9f77cbd430aebd696a2f8dd3bf2.001.1 |
Physical priority index · v5. 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: 2026-09-18T20:52:00.000Z.
First archived: 2026-09-18T20:58:23.558Z. 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 | Morgan, UT; Rich, UT; Weber, UT; Uinta, WY; Davis, UT; Morgan, UT; Weber, UT |
| Headline | Severe Thunderstorm Warning issued September 18 at 2:52PM MDT until September 18 at 3:00PM MDT by NWS Salt Lake City UT |
| Expires | 2026-09-18T15:02:00-06:00 |
| SenderName | NWS Salt Lake City UT |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.1ab72d725fdef9f77cbd430aebd696a2f8dd3bf2.001.1","noaa_urn:oid:2.49.0.1.840.0.acb3e908db4f1d01f8a2a8d521facb80a0768238.001.1"] |
| Iem TypeSummary | H |
| Iem Magnitude | 0.5 |
| Iem Unit | Inch |
| Iem City | Brigham City |
| Iem County | Box Elder |
| Iem State | UT |
| Iem Wfo | SLC |
| Iem Remark | Trained spotter reported. Time estimated from radar. |
| MergedSources | [{"id":"iem_H_41.510_-112.020_1789754400000","source":"iem","severity":"low","severityValue":25,"timestamp":1789754400000,"latitude":41.51,"longitude":-112.02}] |
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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