An exceptionally powerful winter storm will affect the southwestern and northeastern United States.

(CNN) — The next winter storm is already underway and is expected to bring heavy snow, sleet, hurricane-force winds, possible tornadoes and severe flooding as it moves from the southwestern to northeastern United States by midweek.

The first major winter storm of the season continues to dump snow. It dumped more than a foot of snow in the Northeast and brought rain, snow, ice – and even the first tornado of the year – as it moved down the Gulf Coast into Maine.

With this system largely over on Sunday, attention turns to the next system. It is expected to rapidly strengthen into an unusually powerful January storm and produce significant and widespread impacts east of the Rockies beginning Monday.

More than 10 million people are under winter weather warnings from California to Illinois. Millions more will be affected by storm threats in its warmer parts.

Although it will be a fast-moving system, traveling more than 2,800 kilometers in 72 hours, it will produce significant snowfall in more than half a dozen states.

Widespread snow accumulations of at least 15 cm are expected from northern New Mexico to Michigan’s Upper Peninsula.

Heavy snow and strong winds will create blizzard conditions this Sunday as the storm leaves Arizona and moves across the region. Panhandle From Texas (the northernmost part of the state) and Oklahoma this Sunday night. Blizzard warnings were issued for Colorado and New Mexico this Sunday morning.

Poor visibility and near-impossible to difficult driving conditions will begin in the Southwest this Sunday, the Central and Southern Plains this Monday, and the Midwest this Tuesday.

Strong winds will also bring wind chill values ​​below zero degrees in some places across the Plains.

Snow and cold temperatures won’t be the only concerns as the storm moves northeast, intensifying and extending its reach across much of the eastern US by midweek.

Flooding, damaging winds and tornadoes will also be a concern.

Along the Gulf Coast, warm, moist air will fuel the risk of severe storms, including some strong tornadoes and damaging winds.

More than 15 million people are under severe storm threat from Texas to Florida this Monday. More than 35 million people are under the same risk level this Tuesday from the Florida Panhandle to the Outer Banks of North Carolina.

An equally serious concern is the storm’s strong winds carrying water along the coast and the potential for significant flooding from its powerful storm surge.

“Widespread and potentially significant flooding and flash flooding is expected from the central Gulf Coast to much of the eastern US early this week,” the Weather Prediction Center said. “Strong onshore winds will cause widespread coastal flooding along much of the eastern Gulf Coast and eastern seaboard.”

Widespread rainfall of 1 to 3 inches is expected from the Gulf Coast to New England, with isolated spots exceeding 4 inches.

There are concerns about flooding in the Northeast with this next wave of rain after the first storm dumped more than 6 inches of snow in several northeastern states.

Heavy rain will accelerate snowfall and increase the amount of water flowing into waterways, raising the ceiling on the potential for flooding in these areas. As a result, parts of New Jersey, New York and Pennsylvania are at a 3 out of 4 flood risk on Tuesday. A Level 2 threat of 4 extends nearly the entire path of the first storm from Georgia to Massachusetts.

A Level 3 or 4 flood risk was also established along the west coast of Louisiana Panhandle Florida, in the northwest region of the state, due to the potential for flooding due to an early round of rain this Monday.

The rain is both a gift and a concern for Louisiana and Mississippi as they both face severe drought, although they have improved significantly since November following recent rains.

Gulf Coast towns from New Orleans to Tallahassee, Florida, have had more than 4 inches of rain since Dec. 1, so saturated ground won’t take long to flood.

Wind is another cause for concern when the soil is saturated. That makes trees more vulnerable to falling on power lines or buildings. And the wind will be strong enough to cause damage.

“Strong winds on the warm side of the storm could exceed 80 km/h and cause damage from the Appalachians to the east coast,” according to the Weather Forecast Center. The center also warned people to “be prepared for power outages” due to potentially damaging winds.

The strongest winds will be near the coast.

High wind watches are likely to be issued over the next 24 hours, but the National Weather Service office in Boston said the coast may need to issue a hurricane-force wind watch — the same wind warning as a Category 1 hurricane. Areas if the worst storm forecast comes true.

Winds will also cause strong waves of 2 to 3 meters and significant beach erosion is possible. Dangerous rip currents are also likely and will continue through at least mid-week.

The storm system looks to end near the end of the week, but another storm looks like it could follow a similar path and affect similar areas later in the week and into the weekend.