SPC AC 151630

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1130 AM CDT Thu Jun 15 2023

   Valid 151630Z - 161200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
   INTO TONIGHT FROM WESTERN OK AND VICINITY INTO NORTH TX...

   ...SUMMARY...
   Widespread severe storms associated with giant hail (larger than 3-4
   inches in diameter), intense wind damage (greater than 80 mph) and a
   few tornadoes are expected from mid afternoon into tonight across
   western and southern Oklahoma into north and northeast Texas.

   ...Southern Plains this afternoon through tonight...
   A midlevel shortwave trough is moving east-northeastward across
   northern NM as of late morning, and in response to this wave weak
   lee cyclogenesis is underway across northeast NM/southeast CO.  This
   will help draw rich low-level moisture northwestward through the
   afternoon, with mid-upper 60s boundary-layer dewpoints reaching
   western OK/eastern TX Panhandle, and low-mid 70s farther southeast
   into northwest and north TX.  The moistening is occurring beneath
   very steep midlevel lapse rates near 9 C/km, which will contribute
   to extreme buoyancy (MLCAPE in excess of 4000 J/kg) this
   afternoon/evening along the warm front and east of the dryline.

   Severe storm development is expected by early-mid afternoon along
   the dryline from the TX Panhandle into southwest KS, with subsequent
   development on the dryline into northwest TX.  The extreme buoyancy,
   steep lapse rates and very long hodographs will all be quite
   favorable for intense supercells capable of producing giant hail
   (3-4 inches in diameter or greater).  Despite modestly high
   temperature-dewpoint spreads (20 to 25 F) initially, a gradual
   increase in low-level shear/hodograph curvature will support some
   tornado threat late this afternoon/evening.  

   As storms spread eastward this evening, upscale growth into one or
   more clusters appears likely, with an increasing threat for swaths
   of intense gusts in excess of 80 mph.  The corridor of the most
   intense storms is expected across western/southern and parts of
   central OK, as well as north TX.  Thus, the ENH/MDT risk areas have
   been expanded southward and southeastward into TX to reflect both
   the high-end hail threat with the initial supercells, and a high-end
   wind threat with any late evening/overnight storm clusters.

   ...Southeast through this evening...
   Clusters of severe storms are ongoing, along with a few supercells,
   in a broken band along a residual/composite outflow boundary from
   south GA to southern MS.  An embedded mid-upper speed max is moving
   east-southeastward over the lower MS Valley in concert with the
   diurnal heating cycle, which will support continued storm
   development along this corridor through this afternoon/evening. 
   Large CAPE and strong deep-layer vertical shear will favor large
   hail (some of which could exceed 2 inches in diameter) and damaging
   gusts (60-70 mph) as the primary severe threats.  A couple of
   tornadoes may also occur with supercells interacting with the
   residual outflow boundary, primarily across southeast AL/southwest
   GA/FL Panhandle.

   ...OH area this afternoon/evening...
   An embedded shortwave trough is rotating southeastward over Lower
   MI/Lake MI as of late morning, and the zone of ascent preceding this
   trough will affect southeast Lower MI and northern OH later this
   afternoon/evening.  Some increase in midlevel flow and steepening of
   low-level lapse rates will support thunderstorms capable of
   producing strong outflow gusts, and perhaps marginally severe hail.

   ..Thompson/Mosier.. 06/15/2023

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