River Flood Polygon

Beginning December 1^st, 2013, the National Weather Service Forecast Office serving the Baltimore/Washington area will begin issuing polygon-based river flood watches, warnings, and statements for 33 river forecast points in the Potomac, Shenandoah, and Rappahannock River basins.

Instead of highlighting the entire county on the Watch/Warning/Advisory Map on the front page of our web site, only the areas near the stream in proximity to the river forecast point will be highlighted in green. Please keep in mind that the highlighted areas are not to be considered flood inundation maps, but are simply a means to graphically represent select rivers where we provide specific flood forecast and warning services. These highlighted areas will always be larger than the area actually affected, usually around five miles wide.

This change aligns river flood products with other types of flood products issued by the National Weather Service, which are already polygon-based.

In the event of expected or ongoing flooding on December 1^st, the start date of this initiative may be moved either earlier or later.

The National Weather Service welcomes public feedback. If you have any questions or comments on this enhancement, please contact:

Jason Elliott
Senior Service Hydrologist
National Weather Service Baltimore/Washington
43858 Weather Service Road
Sterling, VA 20166
Phone: (703) 996-2234
Email: jason.elliott@noaa.gov