Mesoscale Discussion 1518
   NWS Storm Prediction Center Norman OK
   0224 PM CDT Mon Aug 17 2020

   Areas affected...Portions of central and eastern Oregon

   Concerning...Severe potential...Watch possible 

   Valid 171924Z - 172130Z

   Probability of Watch Issuance...40 percent

   SUMMARY...With mid-level ascent increasing across northern
   California and southern Oregon, widely-scattered to scattered storms
   are expected in central/eastern Oregon this afternoon. Storms will
   pose a threat for damaging wind gusts. Lack of greater buoyancy and
   some question on storm coverage reduces confidence in WW issuance.
   Trends are being monitored.

   DISCUSSION...Mid-level ascent is increasing across northern
   California and south-central Oregon. The leading and weaker edge of
   this ascent is across south-central Oregon and will continue
   north-northeastward this afternoon. Stronger ascent lags southward
   just north of the Bay Area. While this leading area of cloud cover
   creates some uncertainty as to where the strongest storms will
   develop, areas downstream of this ascent have already warmed into
   the low 90s F. Even if storms may initially be elevated, continued
   boundary layer mixing should lead to surface-based storms by 3 PM
   PDT. Storm intensity will be mitigated by fairly weak buoyancy with
   only 250-500 J/kg MLCAPE expected. Despite this, 30-40 kts of
   effective shear and a deep, dry boundary layer should allow a few
   organized storms to transport some of the 40-50 kt cloud-bearing
   flow to the surface. As such, widely-scattered to scattered storms
   will pose some risk for damaging wind gusts. Lingering uncertainty
   with regard to storm intensity and coverage reduces confidence in
   the need for a WW. Trends will continue to be monitored over the
   next few hours.

   ..Wendt/Grams.. 08/17/2020

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

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

   LAT...LON   43221811 42811855 42821954 43122020 43632053 44801967
               45651835 45491730 44641709 43221811