SPC AC 041629

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1129 AM CDT Tue Jun 04 2024

   Valid 041630Z - 051200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
   CENTRAL AND EASTERN OKLAHOMA...

   ...SUMMARY...
   Scattered severe thunderstorms are probable across central and
   eastern Oklahoma this evening.  A tornado and large to very large
   hail will be possible this evening, before severe outflow winds of
   60-85 mph potentially accompany the more intense downdrafts this
   evening into tonight.

   ...Southern Plains to lower MS Valley through tonight...
   Radar/satellite imagery late this morning shows a
   south-southeastward moving MCS along the TX/LA border.  Heating of
   the airmass ahead of the MCS will continue to lead to strong
   destabilization.  A rejuvenation of storm intensity along the
   western flank of the MCS is possible where a reservoir of very rich
   low-level moisture and steep 700-500 mb lapse rates will aid in
   strong/severe storm potential.  Damaging gusts and perhaps large
   hail will be the primary hazards with the stronger storms.

   Outflow from the morning storms will reinforce a composite outflow
   boundary across north TX northward into OK.  It appears that the
   outflow air mass will modify through the day across OK.  Surface
   dewpoints are forecast to increase into the mid 70s across
   central-southern OK where isolated thunderstorm development is
   forecast by late this afternoon/early evening along the edge of
   richer moisture.  Forecast soundings show MLCAPE could exceed 5000
   J/kg with only small convective inhibition.  However, forcing for
   ascent will be rather nebulous and storm initiation/initial coverage
   is uncertain.  Nonetheless, a short window of opportunity may exist
   for a tornado risk if a quasi-discrete mode can occur early in the
   convective life cycle.  Very large buoyancy and nearly dry adiabatic
   lapse rates across OK will support large/tall storms capable of
   producing isolated very large hail initially, and an increase in the
   threat for damaging winds (60-85 mph) as storms grow upscale into
   another MCS tonight.  Have opted to upgrade to a 30-percent
   significant wind area for greater confidence in a severe MCS across
   central/eastern OK.  Farther north, thunderstorms for forecast to
   develop across KS this afternoon into early tonight, as a weak
   surface cold front and associated midlevel trough will move
   southeastward and impinge on the very moist/unstable warm sector. 
   Hail/wind will be the primary risks with those stronger storms.

   ...Mid MO to upper MS Valleys this afternoon/evening...
   A midlevel shortwave trough and associated cold front will move
   eastward from NE/Dakotas to eastern KS/IA and WI by the end of the
   period.  The richest low-level moisture will remain farther south,
   but surface heating in pre-frontal cloud breaks and boundary-layer
   dewpoints in the 60s will contribute to MLCAPE of 1000-2000 J/kg. 
   Some low-level hodographs enlargement in northern MN may aid in some
   brief updraft rotation potential before an extensive band of storms
   becomes outflow dominant.  Vertical shear will be relatively weak in
   the warm sector which will primarily support multicell clusters and
   line segments capable of producing occasional wind damage and
   marginally severe hail.

   ...MO/IL today...
   A midlevel low over west central MO this morning will move
   northeastward toward central/northern IL by this evening.  Lingering
   clouds will tend to slow surface heating, though cloud breaks could
   allow modest destabilization and support a few strong thunderstorm
   clusters capable of producing isolated strong/damaging outflow gusts
   and marginally severe hail.

   ..Smith/Barnes.. 06/04/2024

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