SPC AC 250543

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1243 AM CDT Thu Jun 25 2020

   Valid 251200Z - 261200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
   NORTH-CENTRAL STATES...

   ...SUMMARY...
   Scattered strong/severe thunderstorms are expected across parts of
   the north-central States later this afternoon and evening. Damaging
   winds and hail are the primary threats.

   ...North-Central States...

   Weak mid-level height falls will spread across the northern Rockies
   into the northern Plains later today ahead of a short-wave trough
   that should extend across eastern MT/northwestern WY by 26/00z. At
   low levels, a surface front will surge into the central Dakotas by
   early afternoon, and this boundary should provide the focus for
   scattered thunderstorm development.

   Latest model guidance suggests low-level convergence will not be
   particularly strong along the front, but likely adequate for
   thunderstorm initiation after 21z as surface parcels reach their
   convective temperatures in the mid-upper 80s. While weak convection
   will likely be ongoing at the start of the period ahead of an upper
   vort near the international border, diurnal heating will prove
   instrumental in potential severe due to substantial inhibition.
   Forecast soundings suggest deep-layer wind profiles are more than
   adequate for potential supercells, and initial activity will likely
   be discrete in nature. However, aforementioned weak low-level
   convergence will likely lead to storm mergers during the evening and
   a more complex storm mode should ultimately evolve. Latest CAMs
   support this and wind/hail are the primary risks.

   Upstream across WY, a secondary mid-level disturbance should aid
   convection across higher elevations/High Plains region. This
   activity will propagate toward the NE Panhandle after sunset as the
   front settles into this portion of the central Plains. 

   ...Southern Middle Atlantic/Carolinas...

   Great Lakes/OH Valley upper trough will shift east of the
   Appalachians during the latter half of the period. Latest guidance
   suggests lee trough will evolve across VA/NC and this boundary is
   expected to enhance the possibility for at least isolated afternoon
   thunderstorms as surface temperatures warm to near 80F. Modest
   surface-6km shear would seem supportive of a few robust updrafts
   capable of producing gusty winds, and perhaps some hail across the
   Middle Atlantic region. Farther south across the Carolinas, several
   weak disturbances are embedded within westerly flow along the
   southern fringe of the larger trough. Latest radar data depicts one
   of these features over western GA and another shearing east along
   the central Gulf Coast. Each of these features should encourage
   convection immediately downstream, especially as boundary layer
   warms by mid day. Even so, poor lapse rates and weak shear do not
   look particularly favorable for more than low wind probs.

   ..Darrow/Squitieri.. 06/25/2020

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