By David Shepardson and Allison Lampert

Feb 23 (Reuters) - U.S. airlines were still digging out from a powerful Northeast winter storm that forced more than 8,000 flight cancellations and delays on Monday, with thousands more already scrubbed for Tuesday.

FlightAware, a flight tracking site, said 5,683 flights in the United States had been canceled and 2,703 delayed after more than 11,000 were delayed or canceled on Sunday. Another 2,000 U.S. flights have been canceled for Tuesday.

American Airlines AAL.O said it had been able to resume operations at Washington Reagan National and Philadelphia.

Delta DAL.N and American both said they expect to resume operations at New York's LaGuardia and JFK airports and Boston late on Tuesday morning. Delta also expects to resume Newark flights on Tuesday.

JetBlue JBLU.O was especially hard hit, canceling about 80% of flights due to the storm on Monday, FlightAware said. The airline said in total it has cancelled 1,600 flights through Wednesday.

U.S. passenger railroad Amtrak canceled dozens of trains between New York and Boston and on other routes in the Northeast. Several states ordered motorists to remain off roads for non-essential travel for extended periods due to the significant snowfall.

American, Delta and United all canceled about 20% of flights on Monday. The blizzard dropped more than 2-1/2 feet of snow (76.2 cm) across parts of the U.S. Northeast.

(Reporting by David Shepardson; Editing by Howard Goller)

((David.Shepardson@thomsonreuters.com; 2028988324;))