Strong to severe thunderstorms are possible from the Plains to the Southeast this week as an active stretch of stormy weather takes hold across the Lower 48 states. Gusty winds, hail and isolated tornadoes will be possible in the strongest thunderstorms.
While a large-scale, significant tornado outbreak is not anticipated, the stage is set for multiple rounds of thunderstorms.
Meanwhile, an equally noteworthy risk exists for flooding, particularly from the Interstate 35 corridor in Texas and Oklahoma through the Ozark Plateau, eventually stretching up through the Mississippi, Tennessee and Ohio valleys. Parts of the Mississippi River are under flood warnings, with heavy downpours on the way later this week.
“The main story during the medium-range period will be the continual threat of heavy rain across the central portion of the country,” wrote the Weather Prediction Center, part of the National Weather Service.
The mischievous weather comes during the climatological ramp-up of both the severe weather and spring flood seasons. For many, it’s a reminder of what’s likely to be on the way for April and May as the changing seasons battle it out.
Severe thunderstorm timing
On Tuesday, things kick off over Texas Hill Country and much of the Panhandle. Cities such as Abilene, Lubbock and San Angelo are under a slight risk of severe weather (level 2 out of 5), according to the Storm Prediction Center.
If storms remain isolated at first, a tornado or two is possible initially. Thereafter, the threat becomes predominantly focused on straight-line winds and hail.
By Wednesday, the threat zone nudges east slightly and expands. Lubbock and Abilene again are under a slight risk (level 2 out of 5) but may be joined by Wichita Falls, Tex., and Oklahoma City. Storms on Wednesday may wait to fire until near dusk but could present the risk of damaging winds and a few overnight tornadoes.
Storms may make it as far east as Dallas or Kansas City on Wednesday night; the locations are encompassed within a marginal risk (level 1 out of 5) of severe weather into early Thursday morning.
During the day on Thursday, things become less clear.
“A cold front extending across parts of the southern/central Plains should have numerous to widespread showers and thunderstorms ongoing along its length Thursday morning,” said the Storm Prediction Center. But the severity of those storms is unclear.
Late week and into the weekend, showers and thunderstorms will rumble all the way to the East Coast. There is a chance that a few of these storms could become severe over the Carolinas on Friday.
Regardless of how intense the thunderstorms become, there is a risk of flooding where heavy rain repeatedly moves over the same areas. This could become problematic by Wednesday afternoon over the Southern Plains, somewhere between the Dallas-Fort Worth metroplex and the Red River, along the Oklahoma border.
Different models place the bull's eye of two to three inches of rain in slightly different locations, but there is a risk of excessive rainfall in Dallas, Fort Worth and perhaps Wichita Falls.
Farther south, models are highlighting San Antonio as a secondary location that could see heavy rainfall in the Wednesday-Thursday time frame.
Late on Thursday, the risk of heavy rain expands to Arkansas, the Ozarks, and perhaps parts of the Tennessee and Ohio valleys.
Models diverge in their simulations late this week, indicating decreasing confidence approaching the weekend. But continuing downpours in parts of the Deep South look to bring a few inches of rain to East Texas, northern Louisiana, and extreme northern portions of Mississippi and Alabama.
The South and Southeast have had an early start to their spring flood season, with a number of flood warnings posted along the already-swollen Mississippi River and tributaries. In February, the Pearl River at Jackson, Miss., crested at its third-highest level on record, inundating parts of the state capital.
Alabama also struggled with copious rainfall during February, sparking worries at area dams and shuttering schools in Birmingham. Water rescues were needed in Tuscaloosa on Feb. 10.
Unfortunately, it looks as though heavy rain and flood concerns are likely to persist into late March. The National Weather Service in Memphis wrote that “the unsettled spring pattern appears likely to continue next week.”
Several episodes of storminess have already materialized this past weekend, bubbling up on the leading edge of a chilly air mass exiting the Rockies. To the east, unseasonable warmth has dominated, providing the necessary fuel for thunderstorms.
It’s that sharp contrast of the air masses that will continue to become the focus for severe weather and flooding rains.
That’s thanks to an active jet stream — a river of swiftly moving air at the upper levels of the atmosphere. Given this weather feature overhead, there may be a change in wind speed and direction with height, otherwise known as wind shear. That means that clouds spanning multiple levels in the atmosphere will be sheared, encouraged to spin by the changeable winds.
That doesn’t necessarily mean tornadoes will form. Much will depend on whether storms stay isolated and “discrete,” without having to compete with neighboring storms for energy.