It’s a 15 hour layover. Check in your luggage to the Washington airport, don’t bring any carry on bags. Fly to Philly, rent a car and drive home. The next day, drive to Philly.
On the way back, assuming a connection and stupidly long layover in Philly, skip the flight to DC and take a train home.
If there’s any delay for your flight to Philly, or there’s a travel waiver for snow, you can then drop the DC-PHL flight.
Maybe try to get a longer layover in PHL.