Sandy slowed to a tropical storm overnight, but an Air Force aircraft found hurricane-force winds again Saturday morning, according to the National Weather Service. 

Hurricane Sandy is a Category I hurricane with maximum sustained winds of 75 mph, according to NWS. The difference between Sandy and a tropical storm at this point is 2 mph, with 74 mph being the lowest speed that registers as Category I.

In the face of Hurricane Sandy's northward movement, NWS has issued a flood watch for Prince George's and Montgomery counties, much of Maryland and the DC metro area starting late Sunday through Tuesday morning.

Projections for Sandy show it making landfall late Monday between the Delmarva Peninsula and northern New Jersey, NWS says. The Delmarva Peninsula is a large peninsula on the East Coast; it's occupied by all of Delaware and portions of Maryland and Virginia.

Sandy is expected to produce rainfall levels between 3 and 5 inches in the I-95 metropolitan corridor, with higher amounts possible, according to NWS.

Streams and creeks could rise out of their banks quickly and flood low lying and urban areas due to excessive rainfall.

A flood watch means the potential for flooding exists. People living in areas that are prone to flooding should be prepared to take action should flooding occur.