Web Portal Changes: The Advanced Hydrologic Prediction Service (AHPS) hosted at https://water.weather.gov will be replaced by the National Water Prediction Service (NWPS), with a target of Spring 2024. Existing AHPS content and features will be preserved and expanded within NWPS. The NWS is now accepting feedback on NWPS. Please visit https://www.weather.gov/owp/operations for more information.

Experimental National Water Center Products: Flood Inundation Mapping services are now available for 10% of the U.S. population. Please visit https://www.weather.gov/owp/operations for more information. The National Hydrologic Discussion, Area Hydrologic Discussion, Flood Hazard Outlook, and real-time geospatial services depicting River Forecast Center and National Water Model forecasts, continue to be accessible via the URL above, as described in the StoryMap here.

DID YOU KNOW... Please try our new TEST hydrograph page link at: https://preview.water.noaa.gov/gauges/abcde - Just replace “abcde” with your local hydrograph five character ID found in the lower left corner of the hydrograph.  In late March of 2024, the base URL path will become water.noaa.gov.  Feedback can be provided HERE

Weather Forecast Office Philadelphia/Mount Holly, NJ

Middle Atlantic River Forecast Center

Hydrograph

River at a Glance

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Printable Image About this graph Tabular Data (UTC) Tabular Data (EST) Datum: Not Available Metadata

NOTE: Please refer to our Coastal Hazard Message for specific information regarding Coastal Flood Watches, Warnings and Advisories. Flood impacts are based on long-term averages. Actual impacts from any tidal flooding event may vary due to factors such as rainfall, wave action, and the number of tide cycles during which there is an onshore flow. During tropical cyclones, please refer here for additional storm surge information. NOTE: During a Tropical Storm or Hurricane Watch or Warning, inundation mapping provided by the National Hurricane Center reflects a reasonable worst case scenario. The experimental forecast above is the total water forecast that is expected to occur. NOTE: Forecasts for the Chesapeake Bay at Tolchester Beach (IN MLLW) are issued routinely year-round. Vertical Datum references a tidal datum (MLLW)...for more information see Tides and Currents .

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Flood Categories (in feet) Major Flood Stage: 5.5 Moderate Flood Stage: 4.5 Flood Stage: 3.5 Action Stage: 0 Low Stage (in feet): -9999 Historic Crests (1) 7.91 ft on 09/19/2003 (2) 4.93 ft on 10/30/2021 (3) 4.88 ft on 09/07/1996 (4) 4.86 ft on 09/27/2009 (5) 4.78 ft on 10/30/2012 Show More Historic Crests (P): Preliminary values subject to further review. Recent Crests (1) 4.93 ft on 10/30/2021 (2) 4.52 ft on 10/04/2014 (3) 4.78 ft on 10/30/2012 (4) 4.50 ft on 01/25/2010 (5) 4.86 ft on 09/27/2009 Show More Recent Crests (P): Preliminary values subject to further review. Low Water Records (1) -3.48 ft on 03/03/2018 (2) -3.14 ft on 04/01/1997 For more information on your flood risk go to www.floodsmart.gov. Show FEMA's National Flood Hazard Layers FEMA's National Flood Hazard Layers not showing? Why aren't the FEMA National Flood Hazard Layers showing on the ESRI Map? Possible reasons: There are no FEMA National Flood Hazard Layers for the location which you are viewing on ESRI Maps. The FEMA Web Mapping Service (WMS) is down. Note: Your zoom level may have changed. ESRI's zoom levels must be between 14 and 16 to show National Flood Hazard layers.

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

If you notice any errors in the below information, please contact our Webmaster
7.91	(Mean Lower Low Water (MLLW)) The level reached on September 19, 2003 during Hurricane Isabel.
5.5	(MLLW) MAJOR FLOODING. At this level, widespread roadway flooding begins near the bay and its tidal tributaries in Cecil County and Kent County. Vulnerable homes and businesses may be damaged as water levels rise further above this threshold. Numerous roads become impassable and some neighborhoods may be isolated. The flood waters become a danger to anyone who attempts to cross on foot or in a vehicle.
4.5	(MLLW) MODERATE FLOODING. At this level, additional roadways near the bay and its tidal tributaries in Cecil County and Kent County begin to flood. Lives may be at risk when people put themselves in harm's way. Some damage to vulnerable structures may begin to occur. COASTAL FLOOD WARNING LEVEL.
3.9	(MLLW) Flooding begins in Charlestown along the North East River. Flooding begins in Rock Hall, Skinners Neck, Piney Neck, McKinleyville and Cliffs City. Flooding begins along the Chester River in Chestertown and also south of Chestertown along Quaker Neck Road.
3.8	(MLLW) COASTAL FLOOD ADVISORY LEVEL.
3.5	(MLLW) MINOR FLOODING.

About This Location

Latitude: 39.213300° N, Longitude: 76.245000° W, Horizontal Datum: NAD83/WGS84 River Stage Reference Frame Gauge Height Flood Stage Uses NWS stage 0 ft 3.5 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 -0.92 2.58 Survey grade GPS equipment, FEMA flood plain maps, newer USGS topographic maps NGVD 29 Not Available Not Available Older USGS topographic maps, NGVD29 benchmarks MSL Not Available Not Available Older USGS topographic maps, MSL benchmarks Other -0.81 1.77 NAVD88 to MHHW conversion from NOAA Vertical Datum Transformation (VDatum)

Additional Information

All gage data is referenced in MLLW. During winter months, cold and ice may result in inaccurate real-time stages. Adjustments or deletions of this data can only be done after detailed analysis.

Resources

Hydrologic Resources Text Products Past Precipitation Forecast Precipitation River Forecast Centers River Stage Summary Inundation Mapping Locations

Additional Resources Area Hydrographs NWS Precipitation and River Forecasting AHPS Iframes for Developers Mobile iNWS for emergency management Snow Information Ensemble River Forecasts Hourly Precipitation

Collaborative Agencies The National Weather Service prepares its forecasts and other services in collaboration with agencies like the US Geological Survey, US Bureau of Reclamation, US Army Corps of Engineers, Natural Resource Conservation Service, National Park Service, ALERT Users Group, Bureau of Indian Affairs, and many state and local emergency managers across the country. For details, please click here. NWS Information National Weather Service Philadelphia/Mount Holly Weather Forecast Office 732 Woodlane Road Mount Holly, NJ 08060-9615 (609) 261-6600 Ask Questions/Webmaster Page last modified: 2-Nov-2020 7:30 PM Disclaimer Credits Glossary Privacy Policy About Us Career Opportunities