Right now
The most recent data we hold from NOAA arrived 4 minutes ago, and this point is in it.
2 other detections within 20 km in the last 24 hours, the nearest 15 km from here.
This alert is in force until 9 September 2026, 05:30 UTC.
It is the 2nd strongest of the 121 detections recorded within 20 km of this point since 16 March 2026. Another comparable one was recorded here earlier the same day.
What the source measured
NOAA reported: Flash Flood Warning issued September 8 at 6:29PM CDT until September 9 at 12:30AM CDT by NWS Des Moines IA
An estimated 531,891 people live within 50 km of this point.
Nearby, since 16 March 2026
- May 19, 2026 · score 48 · 6.5 km
- July 3, 2026 · score 48 · 8.6 km
- July 21, 2026 · score 48 · 9.7 km
How we know
Confirmed by 3 independent sources, including NOAA.
Our own score for this event is 48 out of 100, at 92 % confidence.
The score is ours, computed from intensity, exposed population and local history — not the source’s.
Computed under scoring rules v4. Rows carrying other versions were judged by different rules and are not directly comparable.
Event Data
| Type | Severe Weather |
| Severity | High |
| Calamity Score (ours) | 48 / 100 |
| Our confidence | 92% |
| Coordinates | 41.6567, -93.6583 |
| Nearest City | Johnston (4 km) |
| Population Exposed | 531.9K within 50 km |
| Impact Tier | severe |
| Timestamp | 2026-09-08T23:29:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.62b0c660af474e029cf0d46c66d67fb0c439be2b.001.1 |
Score Breakdown
Technical Details
| Event | Flash Flood Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Dallas, IA; Polk, IA |
| Headline | Flash Flood Warning issued September 8 at 6:29PM CDT until September 9 at 12:30AM CDT by NWS Des Moines IA |
| Expires | 2026-09-09T00:30:00-05:00 |
| SenderName | NWS Des Moines IA |
| HasExactCoords | true |
| Spc ReportType | hail |
| Spc Speed | 125 |
| Spc Location | 4 SE Ankeny |
| Spc County | Polk |
| Spc State | IA |
| Spc Comments | Relayed public photo of a hailstone estimated at half dollar sized. Time and location also estimated. (DMX) |
| Iem TypeSummary | H |
| Iem Magnitude | 0.88 |
| Iem Unit | Inch |
| Iem City | 1 NW Altoona |
| Iem County | Polk |
| Iem State | IA |
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.
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