ZCZC SPCSWOMCD ALL
ACUS11 KWNS 201247 
SPC MCD 201247 
TNZ000-KYZ000-ILZ000-MOZ000-ARZ000-201445-

Mesoscale Discussion 1638
NWS Storm Prediction Center Norman OK
0747 AM CDT Thu Jul 20 2023

Areas affected...much of Tennessee and adjacent portions of southern
Kentucky...southeastern Missouri

Concerning...Severe potential...Watch possible 

Valid 201247Z - 201445Z

Probability of Watch Issuance...40 percent

SUMMARY...Intensifying thunderstorm development posing a risk for
severe hail and wind appears possible as early as mid morning into
midday (10 AM-Noon CDT).  Trends are being monitored for the
possibility of a severe weather watch.

DISCUSSION...A remnant westerly mid-level jet streak (including
speeds of 40-50 kt), generated or enhanced by now decayed convection
initially near the Kansas/Oklahoma border earlier this morning,
appears likely to continue propagating east-southeastward across the
Ozark Plateau, toward the Tennessee Valley, through midday.  To the
north of this feature, where seasonably moist low-level air has been
maintained, and mid-level inhibition associated with elevated
mixed-layer air is weaker, forcing along the leading edge of outflow
and/or gravity waves, has been supporting renewed thunderstorm
development.  

More recently, cooling tops have been observed near the leading of
this jet, along its axis, near Poplar Bluff MO.  During the next few
hours, a corridor of strengthening differential surface heating
beneath this regime, across far southeastern Missouri into middle
Tennessee, may provide a focus for considerable boundary-layer
destabilization and weakening inhibition, which could allow for
increasing and intensifying thunderstorm development.  With
mixed-layer CAPE forecast to increase in excess of 2000 J/kg, in the
presence of strengthening deep-layer shear, this could include
supercell structures initially, then one or two upscale growing
clusters.

..Kerr/Guyer.. 07/20/2023

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

ATTN...WFO...MRX...LMK...OHX...HUN...PAH...MEG...

LAT...LON   37258932 37188736 37018605 36068370 35548412 35338536
            35318707 35838827 35968992 36659038 37258932 

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