SPC AC 140532

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1232 AM CDT Tue Aug 14 2018

   Valid 141200Z - 151200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   WYOMING...SOUTHEAST MONTANA...FAR WESTERN SOUTH DAKOTA AND FAR
   WESTERN NEBRASKA...

   ...SUMMARY...
   Marginally severe thunderstorms will be possible late this afternoon
   and early this evening across parts of Wyoming, southeast Montana,
   far western South Dakota and far western Nebraska.

   ...Central and Northern Rockies/Central and Northern High Plains...
   A shortwave trough will move eastward across the central and
   northern Rockies today. At the surface, upslope flow will be in
   place across much of the central and northern High Plains. In
   response, a narrow corridor of maximized low-level moisture is
   forecast to extend from western Nebraska into eastern Wyoming where
   surface dewpoints should be in the lower to mid 50s F. As surface
   heating takes place today, MLCAPE values are forecast to reach the
   1000 to 1500 J/kg range along the moist corridor. Convection should
   initiate in the higher terrain during the afternoon with
   thunderstorms moving eastward into the lower elevations late this
   afternoon into early this evening. RAP forecast soundings at
   Sheridan and Casper at 00Z/Wednesday show 0-6 km shear in the 40 to
   50 kt range with 0-3 km lapse rates approaching 9.0 C/km. This
   should be enough for an isolated severe threat. Marginally severe
   wind gusts will be possible with the stronger cells. Steep lapse
   rates in the mid-levels will also support a threat for hail.

   ..Broyles/Wendt.. 08/14/2018

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