Right now
The most recent data we hold from NOAA arrived 31 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 September 2026 at 06:45 UTC. It is kept here as a record.
It is the 10th strongest of the 49 detections recorded within 20 km of this point since 15 March 2026. The last comparable one was on 15 September 2026. 9 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Flash Flood Warning issued September 16 at 9:45PM MDT until September 17 at 12:45AM MDT by NWS Grand Junction CO
Urban PEI: 19,062 within a heuristic 50 km radius; not unique people.
How we know
2 recorded sources include NOAA; independence is not established by this count.
Our own score for this event is 28 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) | 28 / 100 |
| Legacy data-support index | 0.86/1 |
| Coordinates | 38.6656, -107.9650 |
| Nearest City | Montrose (22 km) |
| Urban exposure index (PEI) | 19.1K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-09-17T03:45:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.7d2f2ca415de238570bc493abab04dc4da94431e.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: 2026-09-17T03:45:00.000Z.
First archived: 2026-09-17T03:49:47.027Z. Material modification: not recorded.
Retained revisions are prospective; earlier versions may be unavailable. No revision entry does not prove that a record never changed.
2026-09-17T04:21:54.752Z · data_change
Index 28 → 28; severity medium → medium; version 5 → 5.
Score Breakdown
Technical Details
| Event | Flash Flood Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Mesa, CO; Gunnison, CO; Hinsdale, CO; Ouray, CO |
| Headline | Flash Flood Warning issued September 16 at 9:45PM MDT until September 17 at 12:45AM MDT by NWS Grand Junction CO |
| Expires | 2026-09-17T00:45:00-06:00 |
| SenderName | NWS Grand Junction CO |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.7d2f2ca415de238570bc493abab04dc4da94431e.001.1","noaa_urn:oid:2.49.0.1.840.0.73f0b275b56d4aba42806388f0ca716585d67d6f.001.1"] |
| Iem TypeSummary | x |
| Iem City | 1 NW Fall Creek |
| Iem County | San Miguel |
| Iem State | CO |
| Iem Wfo | GJT |
| Iem Remark | Two mudslides with debris and boulders near MM1 on Highway 62. |
| MergedSources | [{"id":"iem_x_38.080_-107.700_1789612200000","source":"iem","severity":"low","severityValue":25,"timestamp":1789612200000,"latitude":38.08,"longitude":-107.7},{"id":"iem_F_38.030_-108.110_1789609500000","source":"iem","severity":"low","severityValue":25,"timestamp":1789609500000,"latitude":38.03,"longitude":-108.11},{"id":"iem_x_38.030_-108.050_1789611300000","source":"iem","severity":"low","severityValue":25,"timestamp":1789611300000,"latitude":38.03,"longitude":-108.05}] |
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.
Review the area, threshold and delivery channel in your account.
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