National Weather Service United States Department of Commerce

Powerful Pacific Storm to Continue Impacting Northern California; Heavy Snow in the Appalachians and Portions of the Northeast

A strong atmospheric river will continue to impact northern California with heavy rain and life-threatening flooding through Friday. Unsettled weather is expected across much of the Northeast and Great Lakes over the next few days, including the likelihood of heavy snow in the central Appalachians and higher elevations of northeastern Pennsylvania and southern New York. Read More >

Flash Flood Guidance

 

Flash Flood Guidance is an estimate of the amount of rainfall required over a given area during a given duration to cause small streams to flood. These estimates are based on the current soil moisture and stream flow conditions for the area. Flash Flood Guidance is routinely issued by National Weather Service (NWS) River Forecast Centers, and is used by NWS Weather Forecast Offices when issuing Flash Flood Watches and Warnings to the public. Note: Less rainfall is required to produce flash flooding in urban areas.

 

 


 


 

One-Hour Flash Flood Guidance


 

Latest 1-hour Flash Flood Guidance Graphic.

 

 

Three-Hour Flash Flood Guidance


 

Latest 3-hour Flash Flood Guidance Graphic.

 

 

Six-Hour Flash Flood Guidance


 

Latest 6-hour Flash Flood Guidance Graphic.

 

 


Headwater Guidance Text Product

 

Headwater Guidance

The Flash Flood Guidance Text Products (BOSFFGMA, BOSFFGME and BOSFFGNY) were discontinued on April 1, 2019.