Mesoscale Discussion 0200
   NWS Storm Prediction Center Norman OK
   1056 AM CDT Wed Mar 17 2021

   Areas affected...Central MS...Central AL

   Concerning...Severe potential...Tornado Watch likely 

   Valid 171556Z - 171800Z

   Probability of Watch Issuance...95 percent

   SUMMARY...The environment is becoming increasingly favorable for
   tornadic supercells and a PDS tornado watch will likely be needed
   within the next hour or two.

   DISCUSSION...Regional radar and satellite imagery continues to show
   deepening convection within the broad and robust warm-air advection
   regime across much of MS and AL. Some modest clearing occurred
   briefly ahead of the leading showers over MS and temperatures across
   much of central and southern MS are now in the mid 70s. Slightly
   cooler surface temperatures exist across central/southern AL.
   Dewpoints exhibit a similar trend, with upper 60s/low 70s across
   much of central/southern MS and mid to upper 60s across
   central/southern AL. These thermodynamic conditions have eroded much
   of the convective inhibition across the region, although forecast
   soundings do suggests some minimal (i.e. MLCIN of -25 J/kg or more)
   likely remains in place at the top of the boundary layer. Continued
   moistening of the low-level profile coupled with slight cooling
   aloft should result in a removal of all convective inhibition.

   In addition to improving thermodynamics, the low-level wind fields
   continue to increase. Recent VAD profiles from LIX and DGX show 50
   kts within the 1-2 km layer. Latest VAD from DGX also sampled 0-3 km
   storm-relative helicity over 350 m2/s2. These strengthening
   low-level winds are expected to persist while gradually spreading
   northward/northeastward into more of northern AL. Deep-layer
   vertical shear is already in place over the region, with 0-6 km bulk
   shear currently 50 kt over central MS/AL, increasing to 70 kt over
   northern MS/AL.

   In all, the overall environment is expected to becoming increasingly
   favorable for discrete supercells capable of all severe hazards,
   including intense tornadoes. These initial storms are forecast to
   develop within the 17-19Z time frame. A prolonged threat for
   tornadoes is anticipated across the region, with conditions
   remaining favorable well into the evening.

   ..Mosier/Grams.. 03/17/2021

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...BMX...HUN...MOB...MEG...JAN...

   LAT...LON   32929083 34038838 33898610 32588612 31368837 31479076
               32929083