It's doubtful that they are typical spring-blooming cherries like you'd find in DC blooming, since they REQUIRE a certain number of hours of winter chilling and dormancy before blooming.
More likely they're Prunus subhirtella, which often blooms during winter mild spells anywhere from November to March.
http://www.ces.ncsu.edu/depts/hort/consumer/factsheets/trees-new/prunus_subhirtella_autum.html
At the Brooklyn Botanic Gardens, the 76 double-flowering 'Kwanzan' cherry trees are Prunus serrulata, the same tyoe found in DC.
The Prunus subhirtella, also found at BBG are "weeping cherry " trees.