Multiple storms moving through the country will bring wintry weather up north and flash flood risks across the South until Thursday.
Around 11 million people are under flood watches from southeastern Texas up through southern Tennessee. An additional 55 million are under winter weather advisories from the central Plains into New England.
Eastern Texas, southern Arkansas and northwest Louisiana face the greatest risk of flash flooding on Tuesday. Shreveport, Louisiana, is the largest city under watch, but Houston, Dallas, San Antonio and Austin in Texas could also see flooding.
On Wednesday, the flash flood threat shifts east into parts of central Louisiana, Mississippi and northern Alabama. Jackson, Mississippi, is at the highest risk for flooding, with New Orleans and Atlanta also expected to face localized flooding.
About 4-8 inches of rain is expected across the southern U.S. over the next few days, with some areas experiencing up to 10-12 inches. Strong thunderstorms with damaging winds and an isolated tornado will be possible along the Gulf Coast through Thursday.
San Diego saw a record-breaking 2.73 inches of rain Monday, making it the wettest January day recorded in the city since 1951. Around one month's worth of rain fell in less than six hours, prompting Mayor Todd Gloria to declare a state of emergency.
The same storm that hit San Diego moves east into the Four Corners on Tuesday, bringing rain and mountain snow to Utah, Nevada, Colorado and New Mexico.
More heavy rain will arrive Wednesday on the West Coast as another storm hits the region from Washington down to northern California, including the Bay Area. Heavy snow is possible in parts of the Sierra and Cascade mountains.
A mix of freezing rain and snow is expected this week from Nebraska and Kansas up to the southern Great Lakes and into the Northeast, placing the regions under a winter weather advisory.
Snowfall will be very light, with only about an inch possible for cities like Milwaukee and Boston through Wednesday. However, icing could cause hazardous travel conditions on the road.
The storms will turn into rain on Wednesday as temperatures rise across the eastern third of the country.
