A powerful storm system that originated in the western US over the weekend is now moving eastward, bringing a mix of snow, severe thunderstorms and heavy rain to millions of Americans.
The storm could produce blizzard conditions, tornadoes and flooding in different parts of the country, depending on the location and timing.
Blizzard conditions in the Plains and Midwest
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The storm will intensify as it crosses the Rockies, dumping heavy snow on parts of Colorado, Wyoming, Montana and South Dakota.
Some areas could see up to 2 feet of snow by Tuesday morning, according to the National Weather Service (NWS).
The snow will be accompanied by strong winds, gusting up to 60 mph, creating whiteout conditions and dangerous travel.
The NWS has issued blizzard warnings for parts of Nebraska, South Dakota, North Dakota, Minnesota and Iowa, where visibility could be reduced to near zero and wind chills could drop below zero.
The NWS advises people to avoid travel if possible and to prepare for power outages and tree damage.
The storm will also bring snow to parts of the Great Lakes and the Northeast, but with less intensity and accumulation.
However, the snow could still cause slippery roads and reduced visibility, especially in higher elevations.
While the northern tier of the country deals with snow and wind, the southern states will face a different threat: severe thunderstorms and possible tornadoes.
The storm will tap into warm and moist air from the Gulf of Mexico, creating a favorable environment for thunderstorm development.
The Storm Prediction Center (SPC) has issued an enhanced risk of severe weather for parts of Louisiana, Mississippi, Alabama and Tennessee on Monday, where damaging winds, large hail and a few tornadoes are possible.
The SPC warns that some of the tornadoes could be strong and long-lived, especially in the afternoon and evening hours.
The severe weather threat will shift eastward on Tuesday, affecting parts of Georgia, Florida, South Carolina and North Carolina.
The SPC has issued a slight risk of severe weather for these areas, where isolated tornadoes, damaging winds and hail are possible.
The thunderstorms will also produce heavy rainfall, which could lead to flash flooding in some areas. The NWS has issued flash flood watches for parts of Louisiana, Mississippi, Alabama, Georgia and Florida, where 2 to 4 inches of rain are expected, with locally higher amounts.
Heavy rain and wind in the East Coast
The storm will reach the East Coast by Wednesday, bringing heavy rain and wind to parts of the mid-Atlantic and the Northeast.
The rain could cause localized flooding, especially in urban areas and along small streams and rivers. The wind could cause power outages and coastal erosion, especially along the New England coast.
The storm will also make for another gloomy weekend for parts of the region, where rain has fallen almost every weekend since the end of August.
This could be the eighth consecutive weekend of rain for Philadelphia and the sixth consecutive for New York City.
The storm is expected to move away from the US by Thursday, leaving behind a trail of impacts and damage. It is a reminder of the diverse and extreme weather that can affect the country, especially in the transition seasons of fall and spring.
