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.
Nothing else has been detected within 20 km in the last 24 hours.
This alert expired on 21 July 2026 at 07:15 UTC. It is kept here as a record.
It is the 44th strongest of the 123 detections recorded within 20 km of this point since 16 March 2026. Another comparable one was recorded here earlier the same day. 2 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Flash Flood Warning issued July 20 at 8:18PM CDT until July 21 at 2:15AM CDT by NWS Des Moines IA
Urban PEI: 547,016 within a heuristic 50 km radius; not unique people.
Nearby, since 16 March 2026
- September 8, 2026 · score 48 · 7.4 km
- May 19, 2026 · score 48 · 7.6 km
- July 3, 2026 · score 48 · 7.8 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 41 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) | 41 / 100 |
| Legacy data-support index | 0.80/1 |
| Coordinates | 41.7583, -93.4317 |
| Nearest City | Altoona (13 km) |
| Urban exposure index (PEI) | 547.0K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-07-21T01:18:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Flash Flood Warning_noaa_urn:oid:2.49.0.1.840.0.3a43b22aa06d1277c36f9c85cc405793 |
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: 2026-07-21T01:18:00.000Z.
First archived: 2026-07-21T02:06:41.486Z. 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 | Jasper, IA; Polk, IA; Boone, IA; Jasper, IA; Marshall, IA; Polk, IA; Story, IA |
| Headline | Flash Flood Warning issued July 20 at 8:18PM CDT until July 21 at 2:15AM CDT by NWS Des Moines IA |
| Expires | 2026-07-21T02:15:00-05:00 |
| SenderName | NWS Des Moines IA |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.3a43b22aa06d1277c36f9c85cc405793735307fa.001.1","noaa_urn:oid:2.49.0.1.840.0.1d894347909ee9ac541286dac10e7cd436658459.001.1"] |
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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