See which states are on winter storm alert in the US 0:54
(CNN) --
Several days of heavy rain is forecast for parts of the southern United States this week, which could improve persistent dry conditions but also lead to significant flooding.
“A prolonged rain event is expected in the Mississippi/Tennessee Valleys starting this Monday through the weekend as multiple rain waves move east along a stalled frontal boundary,” he tweeted. the Meteorological Prediction Center.
This stalled front, combined with a column of very moist air rising north from the Gulf of Mexico, will set the stage for a heavy rain event in the Tennessee and Mississippi river valleys Monday through Tuesday.
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Both regions are still grappling with moderate to severe drought conditions (Level 1 and Level 2 of 4), which have expanded across much of Tennessee and northern Alabama over the past week, according to the US Drought Monitor. .
“The flood threat will begin late Monday through early Tuesday in areas south of I-40, especially near the Alabama border,” the National Weather Service office in Nashville, Tennessee, said.
"The flood threat will expand north through (central Tennessee) on Tuesday and Wednesday."
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It's important to note that while "accurate rain forecasts will change, and the main axis of heavy rain may shift to the north or south, several inches of rain are likely to fall," the weather service in Nashville said.
The threat of heavy rain has prompted the forecast center to issue a level 2 of 4 slight risk of excessive rain Monday for nearly 10 million people in parts of Mississippi, Tennessee, Alabama and Georgia, including Atlanta in Georgia, Huntsville in Alabama and Chattanooga in Tennessee.
“There would be a significant swath of more than 2 inches (50.8 mm) of rain primarily in far south Tennessee and northern Alabama,” the forecast center said.
"There is certainly the possibility of isolated or widely scattered amounts of greater than 3 inches (76.2 mm), which could pose a flood threat, especially if that occurs in downtown Huntsville or Chattanooga."
Local weather service offices in Huntsville, Alabama, and in Nashville, Tennessee, may issue flood advisories later this week.
“If the rains become especially heavy or pockets of heavy rain repeatedly move through the same areas, more significant flash flooding will occur,” the weather service in Nashville warned.
Many places in the southern United States could see rain every day this week, including Memphis, according to the weather service.
Another system is forecast to bring even more rain to the southern and eastern United States later in the week as well.
Widespread rain totals of 3 to 5 inches are forecast through Friday, but isolated locations could see higher totals before the end of the week.
Persistent rains this week could reduce drought across the region this week and may also help raise record water levels in the Mississippi River, at least temporarily.
"Flooding may develop, beginning early in the week for low-lying, flood-prone areas, and along small streams," the Nashville weather service said.
“The rises in the larger rivers will occur in the middle to the end of the week.”
The Mississippi River at Memphis is about 8.5 feet (2.5 meters) below low water level.
By Thursday of this week, the number is expected to improve slightly to 5.5 feet (1.67 meters) below low water.
So while the rain will help, it won't be enough to completely fix this problem.
CNN meteorologist Allison Chinchar contributed to this report.
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