Posting this verbatim from Jackson NWS.
Tuesday-Tuesday night: At the start, significant upper level jet &
strong cold frontal system will be taking shape over the central
Plains. Sfc cyclone of 995mb will be deepening over the central
Plains, quickly ejecting E-NE through the mid-MS Valley by midday
Tues & gaining latitude into the N Great Lakes by Tues evening to
Tues night. Sfc frontal system will be diving SE towards the area by
Tues aftn in the ArkLaTex through the Ozarks & Mid-MS Valley by Tues
evening & sweeping through the area by Wed morning. Strong synoptic
jet of 75-85kts @ 500mb & +125kts @ 300mb downstream jet streak
intensifying into the central Plains Tues in advance of mean trough
ejecting out of the Pacific NW with favorable jet
placement/diffluence in the area. Subtropical ridge will deepen over
the W Carribean, keeping the bulk of the trough/forcing & height
falls well off to the NW. However, significant WAA & moisture
advection will bring boundary layer moisture with dewpoints climbing
into the upper 60s-low 70s across the region. With anomalous warmth
& dewpoints, combination of moderate to significant destabilization
& anomalous mean bulk shear aloft will favor significant severe
weather event. This will lead to combination of significant
kinematics & thermo profiles, some values not seen per SPC sounding
climatology (i.e. MLCAPE around 1000-1500 J/kg) & long clockwise
curved hodographs with +300-400 m2/s2 effective SRH & mean layer
bulk shear around 30-45kts in the 0-1km/0-3km & 50-60kts in the 0-
6km layer. This will continue to support all modes of significant
severe weather, including tornadoes, some strong & long track
tornadoes, damaging winds up to 80mph & large hail of golf ball size
or potentially larger. Highest threat looks to be along & NW of the
Natchez Trace corridor. Storm mode looks to be a combination of mid-
morning warm advection showers growing upscale & developing into
supercell mode into the afternoon hours. There are some challenges
on initial development timing & any southern storms developing
across the region, which could limit some inflow of most efficient
moisture. However, this area in SE MS could have better mid-level
capping & 700mb heights which could suppress some convection into
the Pine Belt. After collaboration with SPC earlier today, the
"Moderate" & "Enhanced" risk areas were expanded to the E & SE into
the Hwy 82/Hwy 45 corridors & along I-20 corridors, while the Slight
was also expanded to include the most S & E extreme portions of the
region. Timing for the most significant severe weather looks to be
in the 6PM to midnight timeframe, with some lingering after midnight
through 4AM. The earlier development is tricky & some severe &
tornado potential are possible as early as mid-morning to early aftn
hours. Kept timing as is for now but confidence beginning of the
warm sector supercells is lower while increased confidence of
decreasing severe potential in the Delta around 8PM-11PM in the NW
Delta, the I-55 corridor around midnight or 1AM & most potential
moved out by just before daybreak in E-SE MS.