Valid 121200Z – 131200Z
…THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM MISSISSIPPI
INTO PARTS OF SOUTHERN TENNESSEE…
Widely scattered strong to severe storms are possible late today
into tonight from Mississippi into northern Alabama and parts of
southern Tennessee. A few damaging wind gusts or a brief tornado
will be possible.
…Synopsis and Discussion…
A shortwave trough over TX will eject northeast across the lower MS
Valley and toward the OH Valley while an upper high holds over the
Bahamas. Cooling aloft will arrive after 00Z into MS and TN, near
the right entrance region of the upper jet. At the surface, low
pressure will develop over LA and AR and will move northeastward
toward PA by 12Z Thursday, along with a cold front which will trail
into the northern Gulf of Mexico.
The air mass ahead of the front and low will initially be
cool/stable, but gradual destabilization will occur by late
afternoon and evening. In addition, midlevel lapse rates will be
poor, reducing instability. That said, shear profiles will be
strong, and conditionally favorable for a supercell and/or QLCS.
Weak instability, subtle height falls, and gradually veering
low-level winds may mitigate event magnitude. The greatest threat
area appears to be with linear storms along the front from late
afternoon through evening from MS into southern TN. Damaging wind
gusts are most likely. A brief tornado or two will be possible given
sufficient low-level CAPE and strong wind shear.