** Shares of U.S. airlines fall in premarket trading

** American Airlines AAL.O down 1.2%, United Airlines UAL.O falls 1.4%, Delta Air Lines DAL.N down 1.1%, Southwest Airlines LUV.N down nearly 1% in premarket trade

** Winter storm disrupts travel in the United States, forcing airlines to cancel thousands of flights

** Over 3,600 flights canceled and 714 delayed as of early Monday, according to flight-tracking website FlightAware

** As of last close, Dow Jones U.S. airlines index .DJUSAR down 1.3% YTD

(Reporting by Megavarshini G. Somasundaram in Bengaluru)

((Megavarshini.SomasundaramGnanasundari@thomsonreuters.com))