The National Weather Service has issued a winter storm watchfrom Tuesday morning until Wednesday morning, as back-to-back winter storms are predicted to affect much of the nation this week.A total of three winter storms will bring snow, ice, and rain to more than 40 states, with 29 million Americans facing a winter alert in the Central Plains, the Midwest, the Ohio Valley, and the Mid-Atlantic regions.Winter Storm Harlow is expected to bring ice and snow Tuesday morning into Wednesday to the Ohio Valley, spreading east to the Mid-Atlantic, according to the Weather Channel.This first storm will start in the Central Plains and bring rain and ice to Oklahoma and Arkansas and moderate snow from Kentucky to Maryland, per NBC News. The Mid-Atlantic (which includes Washington, D.C., Maryland, and several contiguous states) may get 3 to 6 inches of snow, Philadelphia may get 2 to 3 inches, and New York City around an inch.Winter Storm Iliana is forecast to bring an even-more wintery mix from Wednesday into Thursday to the Plains and Midwest including Denver, Kansas City, and Oklahoma City, and across the Northeast on Thursday, according to the Weather Channel.This second storm should bring light snow to Colorado, then moderate to heavy snow from Kansas to Michigan, with the heaviest snowfall predicted for Chicago: anywhere between 4 and 8 inches of snow,NBC Chicago meteorologist Alicia Roman said. The storm will then travel north, exiting to Canada, and along the way, bring snow to Boston and the rest of New England, and turning to rain down the coast to Raleigh, North Carolina, per NBC News.Both storms combined are expected to result in large snow totals, and could cause flooding in the South, according to ABC News. A third storm is set to impact California later in the week, bringing heavy rains and high-elevation snows, possibly resulting in flash flooding, with the threat of mudslides across the burn scars of Southern California on Thursday, according to the National Oceanic and Atmospheric Administration (NOAA).