SPC AC 141938

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0238 PM CDT Sun Aug 14 2022

   Valid 142000Z - 151200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS
   AFTERNOON/EVENING ACROSS CENTRAL HIGH PLAINS...NORTHWEST ND...AND
   EASTERN KY VICINITY...

   ...SUMMARY...
   Scattered convection capable of isolated/marginally severe hail and
   wind will spread across portions of the central High Plains,
   northwest North Dakota, and eastern Kentucky and vicinity this
   afternoon and evening.

   ...20Z Update...
   Previous forecast remains on track with no changes needed to the
   preceding outlook. See discussion below for more details.

   ..Mosier.. 08/14/2022

   .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 14 2022/

   ...Central High Plains this afternoon/evening...
   Embedded perturbations will move eastward toward the central High
   Plains, around the north-northwest periphery of the persistent
   midlevel high over the central/southern Plains.  Low-level upslope
   flow will help maintain boundary-layer dewpoints in the mid 50s to
   lower 60s as low-level lapse rates steepen with afternoon
   heating/mixing.  Midlevel lapse rates will not be particularly steep
   within the monsoonal moisture plume, but steepening low-level lapse
   rates and modest deep-layer shear will support the potential for a
   few storm clusters capable of producing strong/isolated severe
   outflow winds this afternoon/evening.

   ...Northwest ND late this afternoon/evening...
   A diffuse surface cyclone/lee trough will persist through the
   afternoon near the MT/ND border, near the southern edge of the main
   belt of mid-upper westerlies over the southern Prairie Provinces. 
   Boundary-layer dewpoints in the mid 60s across western ND, near the
   east edge of the deeper mixing across MT, will support moderate
   buoyancy (MLCAPE of 1500-2000 J/kg) and the potential for isolated
   thunderstorm development near the international border by late
   afternoon.  Assuming a storm or two forms and moves southeastward
   into ND, the environment will conditionally favor some potential for
   supercells/small clusters capable of producing isolated large hail
   and damaging winds for a few hours late this afternoon through late
   evening.

   ...Southern IN to eastern KY/western VA this afternoon/evening...
   A weak surface cyclone will move southeastward from IN toward
   eastern KY, in advance of an embedded speed max digging
   southeastward over IL/IN.  Though clouds will slow surface heating
   some and midlevel lapse rates will not be particularly steep,
   boundary-layer dewpoints well into the 60s and surface heating in
   cloud breaks will support MLCAPE of 500-1000 J/kg.  Deep-layer
   northwesterly shear of 35-40 kt will be sufficient for
   organized/supercell storms capable of producing marginally severe
   hail and isolated wind damage.

   ...South TX this afternoon...
   A tropical low is moving inland over south TX as of late morning,
   with some banded convective structures to the east of the center. 
   Since the low is already inland and is not expected to intensify,
   wind profiles/vertical shear are likewise not expected to
   strengthen.  A weakly rotating storm or two may occur near the lower
   TX coast as the convective bands spread westward/inland, but the
   threat for tornadoes is too marginal to warrant the addition of an
   outlook area.

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