Severe Weather near Greater Upper Marlboro
Right now
The most recent data we hold from NOAA arrived 64 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 March 2026 at 05:45 UTC. It is kept here as a record.
It is the 8th strongest of the 221 detections recorded within 20 km of this point since 16 March 2026. The last comparable one was on 20 March 2026. 113 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Special Marine Warning issued March 20 at 11:50PM EDT until March 21 at 1:45AM EDT by NWS Baltimore MD/Washington DC
Urban PEI: 3,251,811 within a heuristic 50 km radius; not unique people.
Nearby, since 16 March 2026
- July 4, 2026 · score 52 · 1.9 km
- August 8, 2026 · score 52 · 3.8 km
- August 3, 2026 · score 58 · 8.0 km
How we know
24 recorded sources include NOAA; independence is not established by this count.
Our own score for this event is 52 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) | 52 / 100 |
| Legacy data-support index | 0.91/1 |
| Coordinates | 38.7093, -76.7067 |
| Nearest City | Greater Upper Marlboro (14 km) |
| Urban exposure index (PEI) | 3.3M within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-03-21T03:50:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Special Marine Warning_noaa_urn:oid:2.49.0.1.840.0.5797cf101645db51419c9e9a59958ea5 |
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: 2026-03-21T03:50:00.000Z.
First archived: 2026-03-21T16:09:05.806Z. 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 | Special Marine Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Tidal Potomac from Key Bridge to Indian Head MD; Chesapeake Bay from Sandy Point to North Beach MD; Chesapeake Bay from North Beach to Drum Point MD; Eastern Bay; Choptank River to Cambridge MD and the Little Choptank River |
| Headline | Special Marine Warning issued March 20 at 11:50PM EDT until March 21 at 1:45AM EDT by NWS Baltimore MD/Washington DC |
| Expires | 2026-03-21T01:45:00-04:00 |
| SenderName | NWS Baltimore MD/Washington DC |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.5797cf101645db51419c9e9a59958ea545115c0b.001.1","noaa_urn:oid:2.49.0.1.840.0.fae095675cd1904fdb322d46fa20e8494b60b787.001.1"] |
| Iem TypeSummary | M |
| Iem Magnitude | 39 |
| Iem Unit | mph |
| Iem City | 2 E Dahlgren |
| Iem County | King George |
| Iem State | VA |
| Iem Wfo | LWX |
| Iem Remark | A squall produced an estimated wind gust to 34 knots (39 MPH) near the Tower 70 WeatherFlow sensor (XT70). |
| MergedSources | [{"id":"iem_M_38.310_-77.030_1774049820000","source":"iem","severity":"low","severityValue":25,"timestamp":1774049820000,"latitude":38.31,"longitude":-77.03},{"id":"iem_M_38.240_-76.820_1774050960000","source":"iem","severity":"low","severityValue":25,"timestamp":1774050960000,"latitude":38.24,"longitude":-76.82},{"id":"iem_M_38.230_-76.950_1774050720000","source":"iem","severity":"low","severityValue":25,"timestamp":1774050720000,"latitude":38.23,"longitude":-76.95},{"id":"iem_M_38.900_-76.440_1774067340000","source":"iem","severity":"low","severityValue":25,"timestamp":1774067340000,"latitude":38.9,"longitude":-76.44},{"id":"iem_M_38.310_-76.930_1774049580000","source":"iem","severity":"low","severityValue":25,"timestamp":1774049580000,"latitude":38.31,"longitude":-76.93},{"id":"iem_M_38.310_-77.000_1774049880000","source":"iem","severity":"low","severityValue":25,"timestamp":1774049880000,"latitude":38.31,"longitude":-77},{"id":"iem_M_38.320_-77.040_1774049760000","source":"iem","severity":"low","severityValue":25,"timestamp":1774049760000,"latitude":38.32,"longitude":-77.04},{"id":"iem_M_38.220_-76.950_1774049040000","source":"iem","severity":"low","severityValue":25,"timestamp":1774049040000,"latitude":38.22,"longitude":-76.95},{"id":"iem_M_38.270_-76.880_1774050840000","source":"iem","severity":"low","severityValue":25,"timestamp":1774050840000,"latitude":38.27,"longitude":-76.88},{"id":"iem_M_38.640_-77.220_1774045620000","source":"iem","severity":"low","severityValue":25,"timestamp":1774045620000,"latitude":38.64,"longitude":-77.22},{"id":"iem_M_38.340_-76.970_1774049340000","source":"iem","severity":"low","severityValue":25,"timestamp":1774049340000,"latitude":38.34,"longitude":-76.97},{"id":"iem_M_38.340_-76.990_1774051020000","source":"iem","severity":"low","severityValue":25,"timestamp":1774051020000,"latitude":38.34,"longitude":-76.99},{"id":"iem_M_38.330_-77.020_1774048620000","source":"iem","severity":"low","severityValue":25,"timestamp":1774048620000,"latitude":38.33,"longitude":-77.02},{"id":"iem_M_38.630_-77.200_1774045740000","source":"iem","severity":"low","severityValue":25,"timestamp":1774045740000,"latitude":38.63,"longitude":-77.2},{"id":"iem_M_38.850_-77.030_1774045560000","source":"iem","severity":"low","severityValue":25,"timestamp":1774045560000,"latitude":38.85,"longitude":-77.03},{"id":"iem_M_38.340_-76.990_1774047120000","source":"iem","severity":"low","severityValue":25,"timestamp":1774047120000,"latitude":38.34,"longitude":-76.99},{"id":"iem_M_38.340_-76.990_1774050120000","source":"iem","severity":"low","severityValue":25,"timestamp":1774050120000,"latitude":38.34,"longitude":-76.99},{"id":"iem_M_38.340_-76.990_1774048920000","source":"iem","severity":"low","severityValue":25,"timestamp":1774048920000,"latitude":38.34,"longitude":-76.99},{"id":"iem_M_38.640_-77.220_1774046220000","source":"iem","severity":"low","severityValue":25,"timestamp":1774046220000,"latitude":38.64,"longitude":-77.22},{"id":"iem_M_38.920_-77.090_1774045200000","source":"iem","severity":"low","severityValue":25,"timestamp":1774045200000,"latitude":38.92,"longitude":-77.09},{"id":"iem_M_38.310_-77.000_1774050780000","source":"iem","severity":"low","severityValue":25,"timestamp":1774050780000,"latitude":38.31,"longitude":-77},{"id":"iem_M_38.320_-77.040_1774049040000","source":"iem","severity":"low","severityValue":25,"timestamp":1774049040000,"latitude":38.32,"longitude":-77.04},{"id":"iem_M_38.330_-77.020_1774050720000","source":"iem","severity":"low","severityValue":25,"timestamp":1774050720000,"latitude":38.33,"longitude":-77.02}] |
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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