Valid 110100Z – 111200Z
…THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
FAR EAST TEXAS…NORTHERN LOUISIANA AND CENTRAL MISSISSIPPI…
Thunderstorms associated with severe wind gusts, isolated hail and a
tornado or two remain possible this evening, mainly from parts of
east Texas and northern Louisiana into central Mississippi.
…Southern Plains/Lower Mississippi Valley/Central Gulf Coast
The latest water vapor imagery shows west-southwesterly mid-level
flow over much of the southeastern and south-central U.S. A
perturbation in the flow appears to be located in northeast Texas.
Thunderstorms are ongoing ahead of this feature in the Arklatex with
additional storms extending east-southeastward across northern
Louisiana into south-central Mississippi. At the surface, a cold
front is located in east Texas with a surface low in far northwest
Louisiana. Thunderstorms are expected to continue organizing ahead
of the surface low as low-level convergence increases. These storms
will move eastward into the lower Mississippi Valley this evening.
The RAP is analyzing two pockets of moderate instability, one in far
western Louisiana and another in south-central Mississippi. The
Jackson, Mississippi 00Z sounding is sampling this instability with
MUCAPE values near 1200 J/kg. This sounding has 0-6 km shear around
75 kts with 0-3 km storm relative helicity of 275 m2/s2. The
low-level shear should increase as a jet near 850 mb develops across
the Lower Mississippi Valley this evening. For this reason,
supercells with a tornado threat are still possible. Any supercell
could also produce wind damage and hail. For this reason, will
maintain a slight risk area across parts of the Lower Mississippi
Further west, across the southern Plains tonight, isolated
thunderstorms may develop as a mid-level perturbation moves out of
the Rio Grande Valley. RAP forecast soundings in south-central Texas
late tonight show a sharp inversion below 900 mb with MUCAPE around
1000 J/kg and effective shear of 70 kt. This could be enough for
elevated thunderstorms associated with hail.