By Allison Chinchar, Elizabeth Wolfe and Mary Gilbert, CNN
(CNN) — A whirlwind of brutal weather is in store Monday and Tuesday as an exceptionally powerful storm packing nearly every winter weather threat tracks across the US.
This fast-moving storm will unload strong winds, possible strong tornadoes, serious flooding, snow and blizzard conditions, and will cover over 1,800 miles in 72 hours, producing notable snowfall across more than half a dozen states.
The system strengthened as it tracked out of the Four Corners region – where it dumped snow that brought some travel to a halt Sunday – and into the southern Plains Monday afternoon.
Ferocious blizzard conditions are expected from northeast New Mexico and the Texas Panhandle north into parts of Nebraska. The combination of snow and wind will also trigger whiteouts in other parts of the Plains.
The storm’s impacts will also be felt in the Gulf Coast and Southeast Monday afternoon into Tuesday, where nearly 70 million people are at risk for severe weather, including tornadoes, severe wind and flooding rain.
Here’s what to expect as this powerful January storm sets its sights on the central and eastern US.
Tornadoes and severe storms
The threat of flooding, damaging winds and tornadoes is at a risk level more typical of spring than the second week of January.
More than 9 million people are under a Level 3 out of 5 severe storm threat Monday from Texas to Florida. More than 11 million people face the same threat level Tuesday from the Panhandle of Florida to the Outer Banks of North Carolina.
Along the Gulf Coast, warm, moist air will fuel the threat for severe storms that could unleash a few strong tornadoes, damaging winds and hail.
By Monday afternoon, Louisiana, Mississippi and Alabama will be feeling the force of the storm. Tornadoes are likely across the region, and rainfall of 3 to 5 inches could lead to flooding.
A tornado watch was issued Monday afternoon for portions of Texas and Louisiana.
The tornado risk will increase Monday night – an incredibly dangerous situation for parts of the Gulf Coast. Tornadoes at night are twice as deadly as those that occur during the day, mainly because a large portion of the population is asleep and miss warnings.
Meteorologists at the National Weather Service office in Mobile, Alabama, warned of “an extremely high impact event for our area” that “could be one of the more impactful non-tropical systems” to hit their forecast area.
The same system is forecast to move across the Southeast throughout Tuesday. There is a Level 3 out of 5 risk of severe storms for Tallahassee, Florida, Savannah, Georgia, Charleston, South Carolina, and Jacksonville, Florida. Tornadoes and damaging winds are also threats with the strongest storms.
Significant inland and coastal flooding likely
An equally serious concern is the potential for significant flooding from the storm’s strong winds blowing water onshore and its potent rainmaking storms. Flood watches are in place across the Southeast on Monday and in the Northeast on Tuesday.
“Widespread and potentially significant river and flash flooding are likely from the central Gulf Coast through much of the Eastern U.S. early this week,” the Weather Prediction Center said. “Powerful onshore winds will lead to widespread coastal flooding along the eastern Gulf Coast and much of the East Coast.”
Widespread rainfall totals of 1 to 3 inches are expected from the Gulf Coast to New England with isolated locations exceeding 4 inches.
A Level 3 of 4 risk for excessive rainfall and flooding is in place from eastern Louisiana to the Florida Panhandle on Monday.
There’s serious concern for flooding in the Northeast with this next wave of rain coming right after the first snowstorm dropped more than half a foot of snow in multiple Northeast states.
Heavy rain will accelerate snowmelt and increase the amount of water running off into waterways, raising the ceiling on the flood potential in these areas. As a result, there is a Level 3 out of 4 risk for excessive rainfall in portions of the Northeast and the Carolinas on Tuesday. A Level 2 of 4 threat stretches from Georgia through Massachusetts.
The rainfall is both a gift and a concern for Louisiana and Mississippi – both still grappling with serious droughts, though drought has already improved substantially since November from a recent overabundance of rain.
Locations along the Gulf Coast from New Orleans to Tallahassee, Florida, are more than 5 inches above normal for rainfall since December 1, so it won’t take much for the saturated ground to flood.
Strong winds to buffet a large portion of the US
Wind is another concern with saturated ground. It makes trees more vulnerable to toppling over onto power lines or homes. And the winds Tuesday will be strong enough to cause such damage.
Widespread wind gusts of 40 to 60 mph are likely across a wide swath of the central and eastern US as the storm reaches its full strength Tuesday.
The Weather Prediction Center warned people to “prepare for power outages” from the potentially damaging winds.
More than 100 million people across the US are under wind alerts that span Monday, Tuesday or both days.
Coastal areas are likely to endure some of the strongest winds from the storm.
The National Weather Service office in Boston noted they might need to issue hurricane-force wind watches – warning of winds akin to a Category 1 hurricane – for coastal areas if the storm’s worst forecast fears came to pass.
Winds will also trigger high surf from 8 to 11 feet and significant beach erosion is possible. Dangerous rip currents are also likely and will continue through at least the middle of the week.
Blizzard conditions to create treacherous travel
Winter storm alerts stretch over 1,000 miles from Arizona to Michigan as the storm carves its path.
Blizzard warnings are in effect Monday in parts of New Mexico, eastern Colorado, the Oklahoma and Texas Panhandles, western Kansas and southwest Nebraska. Up to a foot of snow could bury parts of the area Monday.
Poor visibility and difficult-to-near-impossible driving conditions will set in for the central and southern Plains on Monday and shift to the Midwest on Tuesday. Heavy snow is likely to target areas from eastern Nebraska and northern Missouri into Michigan Tuesday.
Strong winds will also push wind chill values below zero for some locations in the Plains, especially Monday night and Tuesday night.
Snowfall will then spread into the interior Northeast Tuesday afternoon and evening. Snow will linger, mainly in elevated areas of New York and New England through Wednesday.
The storm looks to wrap up by the end of the week, but another storm could follow a similar path and affect some of the same areas from Friday into the weekend.
CNN’s Robert Shackelford contributed to this report.
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