A surly weather front threatened to drive severe thunderstorms and tornadoes across the south-central U.S. on Tuesday, while what AccuWeather called an "atmospheric fire hose" was forecast to hammer the West.
The nation was bracing for a week of wild, dangerous weather, perhaps none more worrisome than the rare tornadoes capable of staying on the ground for long distances that could develop Tuesday in parts of the South.
Those long-track tornadoes could produce wind gusts of up to 165 mph. A possible tornado sighting was reported early afternoon in Pine Prairie, in south-central Louisiana.
The combination of storms forecasters are predicting could fuel major travel disruptions on the heels of travel issues at the end of Thanksgiving weekend that resulted in 12,000 delayed flights Sunday and Monday, according to the tracking website FlightAware.
The National Weather Service office in Jackson, Mississippi, warned that a "significant, severe weather event is expected to unfold" over the region late Tuesday into Wednesday, carrying the chance of hail the size of tennis balls.
"Strong tornadoes, some possibly significant & long-tracked, are likely," the office tweeted.
Forty million people from Indiana and Illinois down to Texas will be at risk for severe thunderstorms and possibly tornadoes on Tuesday alone, Accuweather said. The National Weather Service warned that severe weather was likely Tuesday across a swath of the Mississippi Valley - Arkansas, Illinois, Kentucky, Louisiana, Mississippi, Missouri and Tennessee.
The weather service's Indianapolis office warned on Twitter that "damaging winds will be the primary threat with lightning and isolated weak tornadoes also possible." The Chicago office cited the "threat for isol'd gusts strong enough to down tree limbs."
AccuWeather Meteorologist Andrew Johnson-Levine said conditions across parts of Louisiana, Arkansas and Mississippi should allow for storms to easily begin rotating, leading to a heightened tornado threat.
"With such an environment in place, a couple of strong, long-lasting tornadoes also cannot be ruled out," Johnson-Levine said.
WHAT IS A NOR'EASTER?Storms can batter East Coast with snow, impact millions of people
Wind gusts could reach 85 mph; outages could target 125M people
A storm triggering severe weather and possible tornadoes in parts of the South from Tuesday to Wednesday will bring a blast of high winds as colder air sweeps from the Midwest to the Northeast, AccuWeather meteorologists warn. High winds and heavy snow in some areas could trigger power outages and travel delays.
More than 125 million people from the Midwest to the Northeast could face disruptive wind gusts of up to 85 mph from the powerful storm system, AccuWeather said.
THOUSANDS OF FLIGHTS DELAYED: 30M at risk for tornadoes, severe storms
Pacific Coast braces for heavy snow, driving rains
Toward the West, a strong cold front accompanied by powerful winds and heavy snow will sweep across portions of the Upper Midwest on Tuesday.
"Heavy snow will develop over the parts of the Mississippi Valley and Upper Great Lakes, which has prompted Winter Storm Warnings and Winter Weather Advisories over the region," National Weather Service Meteorologist Paul Ziegenfelder said.
WHAT IS AN ATMOSPHERIC RIVER?These rivers of water vapor can extend thousands of miles.
The Pacific Coast won't be exempt from the wild weather. A burst of intense moisture known as an atmospheric river, or a plume of intense moisture, will take aim at part of the West Coast and move southward during the middle days of this week, AccuWeather said. Seattle could see its first snow of the season, and an "intense" 8-12 hour period of precipitation could bring dangerous conditions to western Washington from Tuesday night to Wednesday, forecasters say.
The storm will roll into Northern California on Wednesday into Thursday. Southern California could see excessive rains at week's end, AccuWeather warned.
WHAT IS THUNDERSNOW? Explaining how a thunderstorm can produce snow
"While the rain and mountain snow will be beneficial from a drought standpoint, enough can fall to lead to travel delays and disruptions," AccuWeather Meteorologist Haley Taylor said.
This article originally appeared on USA TODAY: Weather forecast brings winter storm warnings and threat of tornadoes