UPDATE 1-Storm paralyzes travel, forcing more than 8,000 US flight disruptions

U.S. airlines ​are set to add flights on ‌Tuesday, ​even as they wrestle with thousands of scrubbed flights the day after a powerful Northeast winter storm forced more than 8,000 cancellations and delays.

The storm blanketed ‌parts of the U.S. Northeast, closing roads and cancelling schools.

With cancellations frustrating travelers on Monday evening, U.S. carriers including United Airlines said they had early plans to ramp up operations on Tuesday, but cautioned that conditions remain ‌challenging. On Tuesday, 7% of U.S. flights are expected to be cancelled, down from just over 19% ‌on Monday, according to data from analytics firm Cirium as of late afternoon. A typical day in the U.S. domestic market has 1% cancellations.

Southwest Airlines said its plan "is on track to start ramping up operations tomorrow, if conditions permit us to safely ⁠do so." The ​Dallas-based low-cost carrier canceled ⁠about 7% of flights on Monday. That was less than its rivals due to the carrier's limited Northeast exposure.

American Airlines said ⁠it had been able to resume operations at Washington Reagan National and Philadelphia. Delta 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 was especially hard hit, canceling about 80% of flights due to the ⁠storm ​on Monday, according to data from FlightAware. 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.