SPC AC 030520

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1220 AM CDT Sat Jun 03 2017

   Valid 041200Z - 051200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
   THE LOWER GREAT LAKES...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE OH VALLEY AND GREAT LAKES...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER THE
   NORTHERN ROCKIES...

   ...SUMMARY...
   Scattered strong/severe thunderstorms are expected across the Ohio
   Valley and adjacent lower Great Lakes region.  Isolated severe
   thunderstorms are also possible across the northern Rockies.

   ...OH Valley/Lower Great Lakes...

   Upper heights are expected to lower across the Great Lakes during
   the day2 period as mid-level troughing begins to establish itself
   over the northeastern US. In response to this evolving trough, a
   surface low is expected to track across northern lower MI into far
   western NY by 05/00z. Deepening westerly flow across the Great Lakes
   and OH Valley suggest low-level lapse rates will steepen due to
   strong boundary-layer heating ahead of a synoptic front. Latest
   model guidance suggests the primary zone of low-level confluence
   should extend from lower MI, southwest into central IL at 18z and
   this boundary should sag south into the OH Valley by early evening.
   Large-scale forcing for ascent will spread into the lower Great
   Lakes which should encourage robust convective development within a
   corridor of strong deep-layer shear. Forecast soundings near Lake
   Erie exhibit SBCAPE on the order of 2000 J/kg with shear profiles
   favoring organized line segments. Damaging winds and hail are the
   primary threats with convection that evolves along the cold front.

   ...Northern Rockies...

   Strong mid-level short-wave trough will move inland across
   OR/northern CA around 18z then eject toward the northern Rockies by
   05/12z. Ahead of this feature, south-southwesterly flow will
   increase at 500mb such that shear profiles will become increasingly
   supportive of organized convection by late afternoon, especially
   from portions of ID into western MT. Strongest convection will
   likely evolve over the northern Rockies where buoyancy is expected
   to be maximized with MUCAPE on the order of 1000 J/kg. Convection
   that evolves over the higher terrain of ID/western MT should track
   northeast producing strong winds and hail.

   ..Darrow.. 06/03/2017

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   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z