Accumulations are still uncertain; but 3-8 inches of snow is widely cited as likely; 1-3 inches by Wednesday morning.
The National Weather Service Winter Storm Watch remains in effect through Wednesday evening, with accumulations of five inches or more possible. There are no significant changes from the previous NWS advisory, though there is still some uncertainty as to the location of the rain-snow line, which will ultimately determine snowfall totals. A Gale Warning has been issued for the Maryland portion of the Chesapeake Bay and Tidal Potomac River Wednesday, which may need to be extended into Wednesday night or Thursday. There is a potential for flooding of creeks and streams if heavy rain occurs Wednesday or if significant snow melt occurs thereafter; minor coastal flooding is likely during high tide Wednesday morning.
Winter Storm Warnings—meaning severe winter weather conditions are expected or occurring—have been issued in western Maryland and Virginia counties for snow accumulations of 10-14 inches between tonight at 1800 hours and midnight Wednesday/Thursday morning. Capital Weather Gang expects warnings to be expanded eastward today (though eastern areas expected to have less impact than areas west of I-95; see accumulations map).
Accumulation estimates are still uncertain, however several sources are indicating between 3-8 inches snow accumulation is likely, with the main precipitation beginning tonight around 1900-2000 hours as rain/snow mix and transitioning into heavy, wet snow early Wednesday. Accumulations by Wednesday morning could be 3-6 inches in the far west suburbs and 1-3 inches in Washington DC; winds expected to pick up after midnight increasing to 15-25 mph and gusty from the northeast. Snow expected to end Wednesday night with gradual warming Thursday into the weekend.
Thanks go to the University of Maryland PD, College Park for this update.