Mesoscale Discussion 1417
   NWS Storm Prediction Center Norman OK
   0251 PM CDT Mon Aug 02 2021

   Areas affected...portions of central into southeast Oregon

   Concerning...Severe potential...Watch unlikely 

   Valid 021951Z - 022215Z

   Probability of Watch Issuance...5 percent

   SUMMARY...A damaging gust or two may occur with the strongest storms
   this afternoon into early evening. The overall severe threat is
   expected to be quite sparse and short-lived, and a WW issuance is
   not expected.

   DISCUSSION...Mostly clear skies have allowed for ample diurnal
   heating, with surface temperatures/dewpoints exceeding 80/50 F per
   latest METAR observations, contributing to 500-1000 J/kg MLCAPE
   (when modifying 17Z RAP forecast soundings). Latest visible
   satellite imagery shows CU field growth over the higher terrain of
   the southern Cascades, and MRMS mosaic radar data shows convective
   initiation in progress. Further heating into the 85-90F range should
   support more robust convective initiation over the next couple of
   hours.

   By 21Z, a well-mixed boundary layer will be in place, fostering
   8.5-10 C/km 0-3km lapse rates. Mainly high-based, pulse-cellular
   storms are expected this afternoon into early evening. The presence
   of 0.75 inch precipitable water values suggests that enough water
   loading in convective downdrafts and subsequent evaporative cooling
   in the deep sub-cloud layer will support some potential for gusty
   winds. However, dewpoints are expected to mix out some by afternoon
   peak heating, constricting skinny CAPE profiles to the 600-300 mb
   layer/above the freezing level. As such, the stronger (potentially
   severe) wind gusts are expected to be quite isolated and brief, and
   a Severe Thunderstorm Watch issuance is not anticipated.

   ..Squitieri/Grams.. 08/02/2021

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...BOI...PDT...MFR...PQR...

   LAT...LON   43002145 43582225 44322233 44452228 44902177 45132102
               45201994 45211933 45021918 44161855 43501808 43071778
               42571798 42171849 42151902 42222000 42512064 42672101
               43002145