Right now
The most recent data we hold from NOAA arrived 10 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 19 September 2026 at 11:45 UTC. It is kept here as a record.
It is the 7th strongest of the 25 detections recorded within 20 km of this point since 14 April 2026. The last comparable one was on 9 September 2026. 5 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Flash Flood Warning issued September 19 at 8:49PM ChST until September 19 at 9:45PM ChST by NWS Tiyan GU
Urban PEI: 120,043 within a heuristic 50 km radius; not unique people.
Nearby, since 14 April 2026
- August 30, 2026 · score 43 · 2.5 km
- August 6, 2026 · score 43 · 7.6 km
- July 10, 2026 · score 43 · 7.9 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
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 | 0.81/1 |
| Coordinates | 13.3253, 144.6700 |
| Nearest City | Mangilao Village (20 km) |
| Urban exposure index (PEI) | 120.0K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-09-19T10:49:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.8e9fe067633ee1fa025d4c6daac829d7db476a51.001.1 |
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: 2026-09-19T10:49:00.000Z.
First archived: 2026-09-19T10:52:45.106Z. 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 | Flash Flood Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Guam, GU |
| Headline | Flash Flood Warning issued September 19 at 8:49PM ChST until September 19 at 9:45PM ChST by NWS Tiyan GU |
| Expires | 2026-09-19T21:45:00+10:00 |
| SenderName | NWS Tiyan GU |
| HasExactCoords | true |
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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