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Flooding in the Delaware River Basin: December 18, 2023

Over the past 24 hours, many locations in the Delaware River Basin have received more than 2-3 inches of rain. Areas in Delaware and in portions of Southwestern N.J. have received more than 5 inches of rain. Many coastal locations experienced tidal flooding, and as with any high-intensity rainfall event, flash flooding in small streams and flood-prone, low-lying and/or urban areas was also a concern. Basin rivers, creeks and streams continue to run high, with flooding occurring or forecasted at several stream gages.

Here’s how much rain fell in a 24-hour period ending 7 a.m. this morning:

MARFC: 24-Hr Rainfall Total as of 7 a.m., December 18, 2023

The DRBC has been monitoring this recent rainfall event and how it is impacting the Delaware River Basin with respect to flooding. Minor or Action Stage flooding is currently occurring or is forecasted at several stream gages within the Basin, including those on tributaries, the non-tidal mainstem or tidal locations.

In the Basin, no Moderate Flooding is expected for any forecast point, save for two locations where moderate flooding is currently occurring: the Neshaminy Creek in Langhorne and the Brandywine Creek at Chadds Ford. No Major Flooding occurred or is forecasted from this rain event.

Flood stage information and forecasts are from the National Weather Service’s Advanced Hydrologic Prediction Service (NWS AHPS). We encourage folks to visit https://water.weather.gov/ahps/ to view up-to-date information. Most forecasts are current as of this afternoon and are anticipated to be updated every 6-12 hours. Please note that the DRBC does not issue flood forecasts, advisories or flood warnings.

Please Note

  • The information provided herein was developed by the National Weather Service Advanced Hydrologic Prediction Service and Middle Atlantic River Forecast Center.

  • This is expected to be our only update on this event. If conditions warrant, the DRBC staff will provide additional updates.

  • All forecasts are subject to change, including storm track, precipitation amounts, predicted stage and crest timing. Be sure to keep up with the most current information.

  • During storm events, we recommend everyone keep a close eye on real-time information from the NWS, NOAA weather radio, local TV, radio, apps – however you get your weather info.

  • Please be on alert for rising water levels and follow instructions of state, county, or local emergency management, first responders, or law enforcement personnel. Note that the DRBC does not issue flood evacuations.

  • Please do not travel on flooded roadways. Turn around, don’t drown!

  • A link to detailed NWS flood stage definitions can be found in the next section, but in brief:

    • No Flooding (green) – river/stream below level where flooding becomes a concern.

    • Near Flood/Action Stage (yellow) – flooding becomes a concern. River/stream is approaching or is forecast to approach the gage height – flood stage – where flooding is defined to begin. Flood stage is an established gage height for a given location at which a rise in water surface level begins to create a hazard to lives, property, or commerce.

    • Minor Flooding (orange) - minimal or no property damage, but possibly some public threat.

    • Moderate Flooding (red) - some inundation of structures and roads near stream. Some evacuations of people and/or transfer of property to higher elevations.

    • Major Flooding (violet) - extensive inundation of structures and roads. Significant evacuations of people and/or transfer of property to higher elevations.

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