The risk will spread east Thursday, affecting places such as New Orleans and Birmingham, Ala., in a slightly tempered state. By Friday, a second system will trigger severe weather along the Interstate 20 corridor from Texas to Mississippi, brewing a tornado risk around Dallas with damaging winds and a few isolated twisters possible farther east.
The storms are likely to shift east over the weekend, sliding along the Gulf Coast on Saturday before heading toward the Southeast and Mid-Atlantic by Sunday.
The pattern should then go virtually silent, with very few thunderstorms over much of the Lower 48. It will mark a stretch of uncharacteristically tranquil weather that could dominate for a week or more as the United States approaches peak tornado season.
Storms to roll across South on Wednesday, Thursday
There were a few showers over Arkansas and Missouri around lunchtime Wednesday, having popped in a souped-up humid air mass that should set the stage for storms later. The triggering upper-air disturbance was rolling through western Oklahoma, Kansas and the Texas Panhandle, supporting rising motion ahead of it and the development of a band of storms along an organizing cold front.
A broken line of thunderstorms, some strong to severe, had taken shape and was stretching roughly from East Texas to near Little Rock and arcing back into central Missouri. Damaging winds should be the main concern, though some tornadoes are possible, too, especially early in the storms’ life cycles when individual thunderstorm cells are fewer and farther between.
A tornado watch was issued for extreme northeast Texas and southeast Oklahoma, northwest Louisiana and most of Arkansas until 8 p.m.. That’s where a few tornadoes, with the outside chance of a strong tornado, are possible.
Ping pong ball-sized hail was reported in Quitman, Ark., about 40 miles north of Little Rock, shortly after 2:30 p.m..
Once they merge, a few tornadoes will be possible along the leading edge of the storms. A strengthening low-level jet stream will cause more wind shear, or a change of wind speed and/or direction with height, that will foster rotation in storms.
The tornado threat will probably wane overnight as storms progress east of the Mississippi River, with a three- or four-hour window of heavy downpours likely in Nashville during the predawn hours. Storms by then will be outrunning their parent cold front, allowing a second band to begin developing during the morning hours Thursday. There’s a marginal risk for strong storms around the Interstate 59 corridor in Alabama and Mississippi on Thursday afternoon.
Another round of storms Friday through Sunday
By Friday, a new disturbance will sling an array of downpours and thunderstorms across the South from Interstate 35 in Texas to the Mississippi Valley. A few severe storms, including the potential for supercells or rotating thunderstorms, are possible around Dallas during the evening. Any supercells that form will bring the risk of large-to-very-large hail, wind and a couple of tornadoes. The tornado risk may grow a bit after dark as the low-level jet strengthens.
The intensifying jet will also increase the chance of a few isolated tornadoes in southern Mississippi. Elsewhere in Mississippi and Alabama, damaging winds and spotty hail are the main storm hazards.
The Storm Prediction Center placed much of Mississippi, including Jackson, in a level 3 out of 5 enhanced risk, an upgrade from previous forecasts that resulted from better computer model agreement.
That system will then head east, carrying the risk of severe storms to the Florida Panhandle, southeastern Alabama and southwest Georgia on Saturday before trucking through the Carolinas and perhaps Virginia on Sunday.
Forecast favors a pause in storm activity next week
Thereafter, severe-weather potential across the Lower 48 largely flatlines. A jet-stream dip, spilling cool air over much of the eastern United States, should become established by early next week. That will impede the return of moisture across the Deep South and the Plains, limiting the amount of instability, or fuel for thunderstorms, that can build.
At the same time, the upper-air pattern will be unfavorable for widespread severe weather, with storm systems likely to pass too far north or east to cook up greater severe-weather potential.
Confidence is low in how the pattern will evolve, but there are some signs that point to a relatively quiet severe-weather pattern sticking around for at least a week or two, and possibly much of April. While a few instances of more localized severe weather are inevitable, the risk for larger-scale episodes or outbreaks should remain lower than average. The prospect of depressed storm activity probably comes to the relief of many beleaguered residents of the South (which has seen multiple tornado outbreaks in recent weeks), though storm chasers have expressed disappointment at the prospects for a slow April.
It’s too early to say what could be in store further out, but some data points to a return of more-typical severe-weather chances in late April into early May. It’s also the climatological peak of the Great Plains severe-weather season, so there will be storms — it’s just a question of how many and how bad.
Moreover, there is no relationship between April tornado frequency and what transpires in May. In other words, even if the country winds up with an easy April, we might not be so lucky in May.