An unfolding storm has begun to threaten Christmas travel across the middle of the United States, Accuweather.com reported Saturday. More than 94 million were expected to drive or fly during the weekend. Accuweather said a heavy coast of ice has fallen in portions of central Oklahoma to central Missouri, and will spread will spread the Northeast during this weekend. The report said thunderstorms were increasing from eastern Texas to the lower Mississippi Valley, and might produce tornadoes Saturday afternoon and evening. Heavier snow was set to develop later farther north and west of the ice over portions of Kansas, northeastward up into northern Michigan and across central Ontario, the report said. The U.S. midsection may see its last pre-Christmas Saturday of the year washed out by a large and vigorous storm system, weather forecasters said. The heavy weather rolled across the lower Mississippi River Valley at midday and stretched as far north as Lake Erie while on its march to the northeast. "The storm this weekend will bring a wide variety of weather ranging from temperature extremes to heavy snow, ice, flooding rain, fog, severe thunderstorms and the potential for tornadoes," AccuWeather said. "The storm will affect major airport hubs from Dallas to St. Louis, Chicago, Detroit, Atlanta, New York City and Boston." The heaviest rain was expected in parts of Arkansas, Louisiana and northern Texas. New England was in line for ice and freezing rain. The bad weather was expected to hamper travel by road as well as air, but probably would not keep too many people at home. USA Today noted the Saturday before Christmas is usually the busiest shopping day of the season after Black Friday.