Right now
The most recent data we hold from NOAA arrived 60 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 21 September 2026 at 01:00 UTC. It is kept here as a record.
No stronger detection stands among the 17 recorded within 20 km of this point since 15 April 2026 — 12 others scored the same. Another comparable one was recorded here earlier the same day. 5 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Flash Flood Warning issued September 20 at 6:27PM CDT until September 20 at 8:00PM CDT by NWS Fort Worth TX
Urban PEI: 81,103 within a heuristic 50 km radius; not unique people.
Nearby, since 15 April 2026
- August 8, 2026 · 4.0 km
- September 21, 2026 · score 32 · 10.1 km
- September 20, 2026 · score 32 · 17.5 km
How we know
2 recorded sources include NOAA; independence is not established by this count.
Our own score for this event is 32 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) | 32 / 100 |
| Legacy data-support index | 0.85/1 |
| Coordinates | 33.7883, -96.5347 |
| Nearest City | Denison (3 km) |
| Urban exposure index (PEI) | 81.1K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-09-20T23:27:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.62d969c2d86b459e20bea767ea95d1e8886586c8.001.1 |
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: 2026-09-20T23:27:00.000Z.
First archived: 2026-09-20T23:32:05.952Z. 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 | Grayson, TX; Bryan, OK |
| Headline | Flash Flood Warning issued September 20 at 6:27PM CDT until September 20 at 8:00PM CDT by NWS Fort Worth TX |
| Expires | 2026-09-20T20:00:00-05:00 |
| SenderName | NWS Fort Worth TX |
| HasExactCoords | true |
| MergedCount | 3 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.62d969c2d86b459e20bea767ea95d1e8886586c8.001.1","noaa_urn:oid:2.49.0.1.840.0.3d09dea64d228e3986e2252fae7e118e0ba0c1cb.001.1","noaa_urn:oid:2.49.0.1.840.0.ed72f6eb668591e0b3a9ad3a17609578a30f514b.001.1"] |
| Iem TypeSummary | F |
| Iem City | 4 S Colbert |
| Iem County | Bryan |
| Iem State | OK |
| Iem Wfo | OUN |
| Iem Remark | Flash flooding along River Road near the Red River. |
| MergedSources | [{"id":"iem_F_33.750_-96.530_1789946400000","source":"iem","severity":"low","severityValue":25,"timestamp":1789946400000,"latitude":33.75,"longitude":-96.53},{"id":"iem_F_33.760_-96.540_1789947600000","source":"iem","severity":"low","severityValue":25,"timestamp":1789947600000,"latitude":33.76,"longitude":-96.54},{"id":"iem_F_33.790_-96.510_1789947300000","source":"iem","severity":"low","severityValue":25,"timestamp":1789947300000,"latitude":33.79,"longitude":-96.51}] |
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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