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 March 2024. Existing AHPS content and features will be preserved and expanded within NWPS.

Experimental National Water Center Products: The National Hydrologic Discussion, Area Hydrologic Discussion, and Flood Hazard Outlook, and real-time geospatial services depicting River Forecast Center and National Water Model forecasts, continue to be accessible via https://www.weather.gov/owp/operations, as described in the StoryMap here.

Weather Forecast Office Gray, ME

Northeast River Forecast Center

Hydrograph

River at a Glance

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Probability Information Weekly Chance of Exceeding Levels Chance of Exceeding Levels During Entire Period Short-term Probabilistic Guidance (Experimental)

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

NOTE: Forecasts for the Souhegan River at Merrimack are issued routinely year-round.

Default Hydrograph Scale to Flood Categories   Return to Area Map

Flood Categories (in feet) Major Flood Stage: 13 Moderate Flood Stage: 11 Flood Stage: 9 Action Stage: 8 Low Stage (in feet): -9999 Historic Crests (1) 16.20 ft on 03/19/1936 (2) 12.78 ft on 09/21/1938 (3) 12.71 ft on 04/17/2007 (4) 11.82 ft on 04/08/1924 (5) 10.88 ft on 06/25/1944 Show More Historic Crests (P): Preliminary values subject to further review. Recent Crests (1) 9.19 ft on 03/31/2010 (2) 9.85 ft on 03/15/2010 (3) 12.71 ft on 04/17/2007 (4) 9.88 ft on 05/15/2006 (5) 9.84 ft on 04/02/2004 Show More Recent Crests (P): Preliminary values subject to further review. Low Water Records Currently none available. 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

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13	Significant flooding affects homes in the area of Beacon Drive in Merrimack. Other low lying sections upstream into Amherst and Milford experience flooding.
11	In Merrimack, homes in the Beacon Drive area flood. Other low lying areas upstream into Amherst and Milford flood.
10	In Merrimack, several homes along a small portion of Beacon Drive begin to flood. In Amherst, low lying areas begin to flood.
9	Flooding of low lying areas along the river begins in the town of Merrimack.

About This Location

Latitude: 42.857500° N, Longitude: 71.506667° W, Horizontal Datum: NAD83/WGS84 River Stage Reference Frame Gauge Height Flood Stage Uses NWS stage 0 ft 9 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 Not Available Not Available Older USGS topographic maps, NGVD29 benchmarks MSL Not Available Not Available Older USGS topographic maps, MSL benchmarks Other NULL NULL   Current/Historical Observations: U.S. Geological Survey (USGS) Data and Site Info for Merrimack

Additional Information

Potential River Levels Used to Estimate the Chance of Flooding and the Range of Possible River Levels 10 Day (HEFS) 7 Day (NAEFS) 7 Day (GEFS) Note: Use the official hydrograph at the top of this web page for river levels within the next 72 hours. Click individual graphics to enlarge.

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 Northeast River Forecast Center 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 Gray Weather Forecast Office P.O. Box 1208, 1 Weather Lane, Route 231 Gray, ME 04039 (207) 688-3216 Ask Questions/Webmaster Page last modified: 2-Nov-2020 7:30 PM Disclaimer Credits Glossary Privacy Policy About Us Career Opportunities