ALERT: Update on status of the nationwide data transmission error that prevents stream gauge data collected at affected locations from being displayed on the Advanced Hydrologic Prediction Services (AHPS) webpages. The USGS has restored the transmission from all of their gauges or has placed them in a seasonal outage (some Alaska gauges). There are a few USGS gauges that the NWS is not yet receiving the new transmissions and NWS is working to get that data by alternate means. A map of the status of USGS gauges is here. The status map of gauge outages from other agencies is here. The situation has greatly improved and will continue to improve but at a slower pace. The outage maps will now be updated once per week on Thursday. We apologize for the service interruption and hope to have the data restored as soon as possible.

Weather Forecast Office (Baltimore/Washington) Sterling, VA

Middle Atlantic River Forecast Center

Hydrograph

River at a Glance

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NOTE: Forecasts for the Potomac River at Harpers Ferry are issued routinely year-round.

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Upstream Gauge

Downstream Gauge

Flood Categories (in feet) Major Flood Stage: 24 Moderate Flood Stage: 21.5 Flood Stage: 18 Action Stage: 16 Low Stage (in feet): -9999 Historic Crests (1) 36.50 ft on 03/19/1936 (2) 34.80 ft on 06/01/1889 (3) 33.80 ft on 10/16/1942 (4) 33.00 ft on 10/01/1896 (5) 30.10 ft on 11/06/1985 Show More Historic Crests (P): Preliminary values subject to further review. Recent Crests (1) 18.33 ft on 09/29/2018 (2) 21.74 ft on 06/04/2018 (3) 19.06 ft on 05/17/2014 (4) 19.14 ft on 05/19/2011 (5) 18.87 ft on 04/18/2011 Show More Recent Crests (P): Preliminary values subject to further review. Low Water Records (1) -2.80 ft on 12/05/1904 (2) -1.70 ft on 12/08/1909

Zoom Level:16 Legend FEMA Layer Gauge Location Disclaimer Latitude/Longitude Disclaimer: The gauge location shown in the above map is the approximate location based on the latitude/longitude coordinates provided to the NWS by the gauge owner.

Flood Impacts & Photos

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43.5	Water approaches the lowest point of Potomac Avenue in Brunswick Maryland.
40	Water reaches the train depot of the MARC and Amtrak station at Harpers Ferry.
33.5	Water reaches the railyard in Brunswick Maryland.
33	Water reaches the second floor of buildings in historic Harpers Ferry along Shenandoah Street.
32	Several private buildings on the lower edge of Harpers Ferry are flooded.
29.5	Floodwaters enter the Storer College exhibit building.
28	All buildings facing Shenandoah Street in historic Harpers Ferry are flooded. Floodwater begins to move up High Street. Potomac Street is flooded beyond Hog Alley and water is approaching private businesses.
25.5	Flood waters reach the general store, and the lowermost portion of the John Brown Story building.
25	Almost all of Shenandoah Street is covered by water. Water reaches the Provost Marshal Office, blacksmith shop, quarters building, and the restrooms on Shenandoah Street. Water also enters the Meriwether Lewis exhibit and White Hall Tavern on Potomac Street, which is covered by water up to Hog Alley.
24.5	Floodwaters reach the Industry Museum in historic Harpers Ferry.
24	Floodwaters reach John Brown Fort, the bookshop, and the A Place in Time Museum in historic Harpers Ferry. Most of Shenandoah Street is flooded and floodwaters cover around half of Arsenal Square. Potomac Street is flooded nearly to White Hall Tavern, but no buildings are impacted on Potomac Street.
23.5	Water approaches John Browns Fort in historic Harpers Ferry. Water surrounds the bookshop and A Place in Time Museum. Water surrounds the blacksmiths shop. Potomac Street begins to flood at the intersection with Shenandoah Street.
22.5	Water begins to approach buildings in historic Harpers Ferry. Most of Shenandoah Street, except between the bookshop and John Browns Fort, is flooded.
21.5	Virtually all of the old federal armory site at historic Harpers Ferry is flooded. Water begins flowing out of the open tunnel between the Potomac and lower town Harpers Ferry, flooding the very end of Shenandoah Street. Backwaters from the Shenandoah River flood even more of Shenandoah Street, including the shuttle bus pavilion.
20.5	Much of the old federal armory site in historic Harpers Ferry is flooded. Backwaters on the Shenandoah flood virtually all areas below the retaining wall and elevated W&P Railroad, and are approaching Shenandoah Street. No buildings are impacted.
19.5	Floodwaters begin to cover the old federal armory site at historic Harpers Ferry. Backwater from the Shenandoah covers most areas between the normal river channel and the elevated Winchester & Potomac Railroad tracks.
18.5	The employee parking lot at historic Harpers Ferry floods.
18	Due to backwater effects on the Shenandoah River, floodwaters cover much of the Hamilton Street area of historic Harpers Ferry, and approach the employee parking lot.
16	Water reaches the C&O Canal towpath on the Maryland side of the river across from Harpers Ferry. The pedestrian bridge crossing between historic Harpers Ferry and the canal will be closed.
Photos (1) 1) Looking upstream at gage (2) 2) Looking from right bank to left bank just below gage (3) 3) Looking downstream at confluence of Potomac/Shenandoah Rivers (4) 4) Looking downstream on Shenandoah left bank just above confluence

About This Location

Latitude: 39.323611° N, Longitude: 77.728889° W, Horizontal Datum: NAD83/WGS84 River Stage Reference Frame Gauge Height Flood Stage Uses NWS stage 0 ft 18 ft Interpreting hydrographs and NWS watch, warnings, and forecasts, and inundation maps Vertical Datum Elevation (gauge height = 0) Elevation (gauge height = flood stage) Elevation information source NAVD88 Not Available Not Available Survey grade GPS equipment, FEMA flood plain maps, newer USGS topographic maps NGVD 29 245.53 ft 263.53 ft Older USGS topographic maps, NGVD29 benchmarks MSL Not Available Not Available Older USGS topographic maps, MSL benchmarks Other Not Available Not Available

Additional Information

This gage does not provide readings below 3.1 feet. To determine an estimation of values at low water, view the Point of Rocks gauge. At low water, values at Harpers Ferry are generally within a quarter foot - usually slightly higher - of those at Point of Rocks. Streamflow is typically a few hundred cfs lower at Harpers Ferry than Point of Rocks at low water.

Resources

Hydrologic Resources Text Products Past Precipitation Forecast Precipitation River Forecast Centers River Stage Summary Automated Flood Warning Systems Inundation Mapping Locations

Additional Resources Area Hydrographs NWS Precipitation and River Forecasting AHPS Iframes for Developers Mobile iNWS for emergency management Flood Damage Costs/Fatalities in the US, 1903 - 2014 AHPS Web Brochure Snow Information Ensemble River Forecasts Hourly Precipitation

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