Right now
The most recent data we hold from NOAA arrived 7 hours 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 March 2026 at 07:00 UTC. It is kept here as a record.
It is the 2nd strongest of the 84 detections recorded within 20 km of this point since 12 March 2026. Another comparable one was recorded here earlier the same day. 40 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Flash Flood Warning issued March 20 at 6:49PM HST until March 20 at 9:00PM HST by NWS Honolulu HI
Nearby, since 12 March 2026
- March 20, 2026 · score 22 · 0.0 km
- May 16, 2026 · score 22 · 3.3 km
- May 16, 2026 · score 22 · 6.0 km
How we know
3 recorded sources include NOAA; independence is not established by this count.
Our own score for this event is 22 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) | 22 / 100 |
| Legacy data-support index | 0.72/1 |
| Coordinates | 21.4980, -158.0192 |
| Nearest City | Wahiawā (0 km) |
| Urban exposure index (PEI) | 0 within 50 km |
| Impact Tier | minor |
| Timestamp | 2026-03-21T04:49:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Flash Flood Warning_noaa_urn:oid:2.49.0.1.840.0.9e845e00f7aa964a558026fe33f22603 |
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: 2026-03-21T04:49:00.000Z.
First archived: 2026-03-21T17:10:25.184Z. 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 | Oahu in Honolulu, HI |
| Headline | Flash Flood Warning issued March 20 at 6:49PM HST until March 20 at 9:00PM HST by NWS Honolulu HI |
| Expires | 2026-03-20T21:00:00-10:00 |
| SenderName | NWS Honolulu HI |
| HasExactCoords | true |
| MergedCount | 3 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.9e845e00f7aa964a558026fe33f22603594ab282.001.1","noaa_urn:oid:2.49.0.1.840.0.0d4aea42da972260705f3871f548932bd1b4f337.001.1","noaa_urn:oid:2.49.0.1.840.0.740b531802dc2e17b6e390de65328397bf961df3.001.1"] |
| Iem TypeSummary | F |
| Iem City | 2 WNW Makaha Valley |
| Iem County | Honolulu |
| Iem State | HI |
| Iem Wfo | HFO |
| Iem Remark | Road closed both directions due to extreme flooding earlier in the morning. Part of the roadway collapsed, sending a vehicles over the edge. |
| MergedSources | [{"id":"iem_F_21.580_-158.110_1774055460000","source":"iem","severity":"low","severityValue":25,"timestamp":1774055460000,"latitude":21.58,"longitude":-158.11},{"id":"iem_F_21.500_-158.230_1774047780000","source":"iem","severity":"low","severityValue":25,"timestamp":1774047780000,"latitude":21.5,"longitude":-158.23}] |
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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