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 Buffalo, NY

Ohio 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: NAVD88 Metadata

NOTE: Forecasts for the Allegheny River at Olean are issued routinely year-round.

Default Hydrograph Scale to Flood Categories   Return to Area Map

Upstream Gauge

Downstream Gauge

Flood Categories (in feet) Major Flood Stage: 23 Moderate Flood Stage: 17 Flood Stage: 12 Action Stage: 10 Low Stage (in feet): -9999 Historic Crests (1) 26.20 ft on 06/23/1972 (2) 23.30 ft on 07/19/1942 (3) 19.50 ft on 03/08/1956 (4) 19.30 ft on 05/29/1946 (5) 18.60 ft on 01/20/1996 Show More Historic Crests (P): Preliminary values subject to further review. Recent Crests (1) 13.33 ft on 02/19/2022 (2) 13.91 ft on 01/14/2018 (3) 14.17 ft on 01/13/2017 (4) 17.74 ft on 12/03/2010 (5) 12.34 ft on 03/11/2009 Show More Recent Crests (P): Preliminary values subject to further review. Low Water Records (1) 0.50 ft on 08/03/1999 (2) 1.00 ft on 09/01/1998 (3) 1.15 ft on 08/10/2016

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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25	Extreme flood, extensive residential flooding begins, especially upstream from Union Street bridge. Some evacuations necessary. Serious flooding upstream through Portville. Dikes overwhelmed.
23	Major flood, protective dikes begin to be topped. Some roadway flooding in residential areas of city begins, especially upstream. Serious flooding in areas unprotected by dikes including portions of Portville.
17	Moderate flood, water affects Riverview School of Aviation, 1.5 miles upstream of Union Street bridge. Local flooding occurs in areas unprotected by dikes including portions of Portville upstream.
12	Flood stage, flooding possible on Union Street in Allegany and East Riverside Drive 1 to 3 miles upstream of Olean. Some farm lands along the river are also impacted.
10	Action stage, high flows. No flooding.

About This Location

Latitude: 42.072222° N, Longitude: 78.451944° W, Horizontal Datum: NAD83/WGS84 River Stage Reference Frame Gauge Height Flood Stage Uses NWS stage 0 ft 12 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 1399.50 ft 1411.50 ft Survey grade GPS equipment, FEMA flood plain maps, newer USGS topographic maps NGVD 29 1399.98 ft 1411.98 ft Older USGS topographic maps, NGVD29 benchmarks MSL Not Available Not Available Older USGS topographic maps, MSL benchmarks Other Not Available Not Available   Current/Historical Observations: U.S. Geological Survey (USGS) Data and Site Info for Olean

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 48 hours. See the Product Description Document link for more details on the interpretation of the 3,7 day graphics. Click individual graphics to enlarge. Observations courtesy of the town of Olean.

Resources

Hydrologic Resources Text Products Past Precipitation Forecast Precipitation River Forecast Centers River Stage Summary Ohio Basin Water Resouces Outlook 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 Ohio 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 Buffalo Weather Forecast Office 587 Aero Drive Buffalo, NY 14225-1405 (716) 565-0204 Ask Questions/Webmaster Page last modified: 2-Nov-2020 7:30 PM Disclaimer Credits Glossary Privacy Policy About Us Career Opportunities