Right now
The most recent data we hold from NOAA arrived 9 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 4 September 2026 at 04:15 UTC. It is kept here as a record.
No stronger detection stands among the 114 recorded within 20 km of this point since 12 March 2026 — 66 others scored the same. Another comparable one was recorded here earlier the same day.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued September 3 at 11:37PM EDT until September 4 at 12:15AM EDT by NWS Baltimore MD/Washington DC
Urban PEI: 4,969,323 within a heuristic 50 km radius; not unique people.
Nearby, since 12 March 2026
- September 4, 2026 · score 46 · 0.0 km
- March 17, 2026 · 7.0 km
- July 5, 2026 · 8.0 km
How we know
4 recorded sources include NOAA; independence is not established by this count.
Our own score for this event is 46 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 v4. Rows carrying other versions were judged by different rules and are not directly comparable.
Event Data
| Type | Severe Weather |
| Severity | Medium |
| Calamity Score (ours) | 46 / 100 |
| Legacy data-support index | 0.91/1 |
| Coordinates | 38.9831, -77.0941 |
| Nearest City | Bethesda (1 km) |
| Urban exposure index (PEI) | 5.0M within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-09-04T03:37:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.260665100174dae376a0e7925248211c7c6c24ca.001.1 |
Physical priority index · v4 (historical). 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: 2026-09-04T03:37:00.000Z.
First archived: 2026-09-04T03:43:23.175Z. 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 | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | District of Columbia, DC; Montgomery, MD; Prince Georges, MD; Arlington, VA; Fairfax, VA; City of Alexandria, VA; City of Falls Church, VA; Montgomery, MD; Fairfax, VA; Loudoun, VA |
| Headline | Severe Thunderstorm Warning issued September 3 at 11:37PM EDT until September 4 at 12:15AM EDT by NWS Baltimore MD/Washington DC |
| Expires | 2026-09-04T00:15:00-04:00 |
| SenderName | NWS Baltimore MD/Washington DC |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.260665100174dae376a0e7925248211c7c6c24ca.001.1","noaa_urn:oid:2.49.0.1.840.0.ae39e1423cd88ff6a0edae6b14ab203a99fd8e90.001.1"] |
| Spc ReportType | wind |
| Spc Speed | UNK |
| Spc Location | 3 E Buckeystown |
| Spc County | Frederick |
| Spc State | MD |
| Spc Comments | Tree down along Park Mills Road. Time estimated via radar. (LWX) |
| Iem TypeSummary | D |
| Iem City | Frederick |
| Iem County | Frederick |
| Iem State | MD |
Safety Information
Always follow official guidance from your local emergency management agency. This platform provides scientific monitoring data and is not a substitute for official warnings. If you are in immediate danger, contact your local emergency number.
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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