Weather WKY

 Mesoscale Discussion 0242
   NWS Storm Prediction Center Norman OK
   0401 AM CST Fri Mar 03 2023

   Areas affected...portions of northern MS/AL...western into Middle
   TN...western KY...far southeast MO...and far southern IL

   Concerning...Severe potential...Watch likely 

   Valid 031001Z - 031230Z

   Probability of Watch Issuance...80 percent

   SUMMARY...A new tornado watch will likely be needed by 13-14z/7-8 am
   CST across portions of the Tennessee and Lower Ohio Valleys.
   Damaging gusts and a few tornadoes will be possible through
   midday/early afternoon.

   DISCUSSION...A quasi-stationary boundary is evident in surface
   analysis extending from west-central TN toward the TN/KY border
   vicinity north of Nashville. Meanwhile, the warm front, demarcating
   mid-60s F surface dewpoints from upper 50s to low 60s F dewpoints,
   is arcing from near Memphis into east-central MS (between Starkville
   and Tupelo) and central AL. Large-scale ascent ejecting into east
   TX, as the mid/upper trough becomes more negatively tilted as of
   10z, will aid in deepening of the surface low over central AR as it
   tracks northeast toward the Lower OH Valley through midday. As this
   occurs, the warm front will lift northward, allowing for
   destabilization of the airmass downstream from WW 59 across parts of
   northern MS into western and Middle TN, and eventually northward
   toward the lower OH River. 

   Ongoing precipitation across parts of western/Middle TN/southeast
   MO/western KY and vicinity lends to some uncertainty with respect to
   the northern extent of severe potential through the morning, and
   possible watch issuance. While a relative minimum in severe activity
   may exist in the short term, as the warm front surges northward
   through mid-morning, forecast soundings in addition to CAMs and
   deterministic guidance suggest organized convection will develop
   northeast from near the MS River through western KY.

   Where the more moist and unstable airmass evolves, sufficient
   low-level instability, in the presence of intense low-level shear
   (aided by a 50-60 kt 850 mb jet), will support organized linear
   convection with perhaps embedded or semi-discrete cells. Damaging
   gusts and a few tornadoes will be possible with this activity
   through midday/early afternoon. A downstream watch will likely be
   needed by around 13z-14z.