A deep freeze enveloping most of the United States early on Friday combined with a massive winter storm brewing in the Midwest to leave two-thirds of the nation under extreme weather alerts, confounding travel plans for millions of Americans.
Heading into the Christmas holiday weekend, the looming storm was forecast to develop into a “bomb cyclone,” unleashing heavy, blinding snow from the northern Plains and Great Lakes region to the upper Mississippi Valley and western New York.
Numbing cold intensified by high winds was expected to extend as far south as the U.S.-Mexico border.
Hard-freeze warnings were posted across the Gulf Coast states of Texas, Louisiana, Alabama and Florida, while significant icing was possible from a separate arctic blast hitting the Pacific Northwest.
By late Thursday, most of the Lower 48 states, from Washington state to Florida, were under wind-chill alerts, blizzard warnings or other winter weather advisories affecting more than 200 million people, about 60% of the U.S. population, the National Weather Service (NWS) reported.
The NWS map of existing or impending wintry hazards, stretching from border to border and coast to coast, “depicts one of the greatest extents of winter weather warnings and advisories ever,” the agency said.
The bomb cyclone could unleash snowfalls of a half inch (1.25 cm) per hour driven by gale-force winds, cutting visibility to near zero, the weather service said.
Combined with the arctic cold, wind-chill factors as low as 40 degrees below zero Fahrenheit (minus 40 Celsius) were forecast in the High Plains, the northern Rockies and the Great Basin, the NWS said. Exposure to such conditions without adequate protection can cause frostbite within minutes.