NEW ORLEANS (AP) - Christmas Day along the Gulf Coast is filled with severe thunderstorms that are bringing drenching rains, high winds and damaging tornadoes while the nation's midsection is dealing with freezing rain, sleet and snow.

Winds toppled a tree onto a pickup truck in the Houston area, killing the driver. And icy roads already are being blamed for a 21-vehicle pileup in Oklahoma, where authorities warned would-be travelers to stay home.

Tornado watches are in effect across southern Louisiana and Mississippi.

Nearly 350 flights nationwide have been canceled so far, according to the flight tracker FlightAware.com. More than half were canceled into and out of Dallas/Fort Worth International Airport which got a few inches of snow.

Meanwhile, blizzard conditions are possible for parts of Illinois, Indiana and western Kentucky with predictions of 4 to 7 inches of snow. Much of Oklahoma and Arkansas is bracing under a winter storm warning of an early mix of rain and sleet forecast to eventually turn to snow. About a dozen counties in Missouri are under a blizzard warning from tonight to noon tomorrow.