Mesoscale Discussion 1820
   NWS Storm Prediction Center Norman OK
   0204 PM CDT Sun Oct 10 2021

   Areas affected...Parts of southwestern through north central
   Oklahoma and adjacent portions of northwest Texas and south central
   Kansas

   Concerning...Severe potential...Watch likely 

   Valid 101904Z - 102100Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Increasingly widespread and intensifying thunderstorm
   development appears probable in a corridor across southwestern
   through north central Oklahoma, including the Greater Oklahoma City
   area, as well as adjacent portions of northwest Texas and south
   central Kansas, by 5-7 PM.  Some of this activity will pose a risk
   for severe hail initially, with increasing potential for a few
   tornadoes by early evening.

   DISCUSSION...A weak surface cold front has stalled south of Wichita,
   KS, south-southwestward into areas near/east of Childress, TX, where
   a surface low is beginning to form near the nose of a corridor of
   stronger boundary-layer heating and deeper mixing, beneath a plume
   of capping elevated mixed-layer air across the southern Great
   Plains.  A dryline is becoming better defined east and south of the
   surface low, and boundary-layer moisture is gradually increasing
   along and ahead of the front to the northeast of the surface low.

   Due to the initially modest moisture relatively to the warmth of the
   elevated mixed-layer, latest objective analysis indicates that warm
   sector boundary-layer CAPE remains fairly weak (500-1000 J/kg). 
   However, it appears that this will begin to substantively change
   during the next few hours, as the leading edge of mid-level forcing
   for ascent and cooling now overspreading the Texas Panhandle/South
   Plains progresses eastward.

   Weakening inhibition and increasing mixed-layer CAPE likely will
   coincide with strengthening deep-layer shear accompanying a 50-70+
   kt southwesterly 500 mb jet streak, contributing to an environment
   conducive to organized severe thunderstorm development.  It seems
   probable that this will include a rapidly upscale growing line of
   storms along/ahead of the front by early evening.  However, initial
   storm development may include isolated to scattered discrete
   supercells, particularly in a possible cluster near/northeast of the
   surface low and dryline across southwestern Oklahoma.

   South-southwesterly flow in the 850-700 mb layer is initially rather
   modest, but forecast to strengthen to 30-40+ in the vicinity of the
   intensifying convective development, generally along the Interstate
   44 and 35 corridors (near and southwest through north of the
   Oklahoma City metropolitan area) by around 00-01Z.  This will
   contribute to enlarging low-level hodographs supportive of
   strengthening low-level mesocyclones, posing a risk for tornadoes,
   in addition to severe hail.

   ..Kerr/Hart.. 10/10/2021

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

   ATTN...WFO...TSA...ICT...OUN...LUB...

   LAT...LON   35069977 35839849 37299712 36439647 34669803 33959908
               34490009 35069977