The new year is just days away, and it looks like 2023 will begin with a lot of weather activity across the South. Multiple storm systems are expected to roll across the south-central United States in the days ahead, setting the stage for flooding rains, damaging winds and perhaps some tornadoes.
The National Weather Service Storm Prediction Center has outlined a level 2 out of 5 “slight” risk for severe weather on Monday in a region including Dallas, Memphis, Little Rock, Shreveport, La., Jackson, Tenn., Evansville, Ind., and Tupelo, Miss.
A widespread 4 to 7 inches of rain is expected to soak the South over the next five days, with localized flooding possible from East Texas along the Interstate 10 and I-20 corridor up the lower Mississippi Valley into Illinois and east to Georgia. Atlanta, home to Hartsfield-Jackson, the busiest airport in the world, also could be drenched for days.
The disturbed weather has the potential to disrupt travel plans at the beginning of the year, coming on the heels of a particularly chaotic Christmas holiday travel stretch in the United States..
Heavy rain setup
The overarching pattern is dominated by a trough, or dip in the jet stream, in the West. A ridge of high pressure will become established and park over the eastern United States.
That high will bring temperatures 15 to 20 degrees above average in spots. In D.C., which last week dealt with readings as low as 9 degrees and experienced its coldest December reading in 33 years, there should be highs in the mid-60s amid an early taste of spring.
In the western United States, however, that trough — filled with cooler air and low pressure — will keep conditions unsettled while maintaining temperatures about 5 to 10 degrees below average.
The two air masses are expected to clash over the central United States along a stalled cold front that should stream moisture northward.
Heavy rain is likely in the lower Mississippi Valley on Friday, shifting into parts of the Deep South, including the Gulf Coast from Louisiana to the Florida Panhandle, in the evening. By Saturday morning, storms and downpours are expected to be rolling through Georgia and South Carolina, with a second batch of more-moderate rainfall in the Ohio Valley. Both areas of inclement weather should meet in the Mid-Atlantic with some showers on Saturday afternoon.
The second system, the same that will deliver severe weather to the South, also could bring another round of heavy rainfall. That rain will take the form of scattered thunderstorms after lunchtime Monday along and east of the I-35 corridor in Texas and Oklahoma. Then storms are expected to combine to create a stream of downpours and thunderstorms that will roll east, dropping another couple inches of rain. That system is expected to move through Mississippi and Alabama on Tuesday, with additional downpours in the Midwest.
The American GFS model simulates a widespread 3 to 5 inches of rain falling between the two storms in East Texas, Louisiana, Arkansas, Mississippi, Alabama, Georgia, West Tennessee and along parts of the Ohio River in western Kentucky and southern Illinois. There could be localized totals of up to seven inches in Georgia.
Fortunately, since the rain will be spread over two events, there may be a lower flood risk. Still, plan for challenging travel on Interstates 10, 20, 22, 30, 40 and 59.
Severe weather risk
Monday’s episode of active weather also will feature some severe storms. The instigator, an upper-air disturbance, is south of the Alaskan Aleutians, but it is expected to dive southeast in the coming days. A pocket of vorticity, or spin, within the system will enhance upward motion in the air ahead of it, brewing scattered to widespread showers and thunderstorms across parts of the South on Monday.
Storms are likely to begin Monday after lunchtime in eastern Oklahoma and near and east of Dallas. They should grow into a sheared environment, or one characterized by changing winds with height. That could encourage thunderstorms to rotate, presenting a tornado risk.
They are likely to march northeast, affecting the greater Ark-La-Tex region. Storms eventually may merge into a line and continue east with additional damaging winds or spin-up tornadoes. Mississippi, Alabama and West Tennessee will have to monitor that threat closely into early Tuesday.