Mesoscale Discussion 1703
   NWS Storm Prediction Center Norman OK
   0656 PM CDT Thu Sep 17 2020

   Areas affected...Willamette Valley and Vicinity

   Concerning...Severe potential...Watch possible 

   Valid 172356Z - 180200Z

   Probability of Watch Issuance...40 percent

   SUMMARY...A few organized/rotating storms are expected to develop
   later this afternoon and early evening along and west of the Cascade
   crest. Storms will be capable of strong wind gusts as well as large
   hail. Buoyancy is limited across the region which increases the
   uncertainty in the coverage of severe-caliber storms. A severe
   thunderstorm watch may be considered if convective trends warrant.

   DISCUSSION...A lobe of mid-level ascent is evident on satellite
   water vapor imagery off the southwest coast of Oregon. This ascent
   has already contributed to increasing low to mid-level cumulus
   development from the coastal ranges to the southern Cascades. In
   spite of persistent smoke cover, temperatures have managed to climb
   into the mid 70s F near Portland to the upper 70s F near Medford.
   Continued mid-level cooling into the evening is expected to support
   500-1000 J/kg MLCAPE. With limited buoyancy, the coverage of severe
   storms is a bit uncertain. However, with strong effective shear
   (45-55 kts) present, a few organized/rotating storms will likely
   evolve out of the deepening cumulus activity along and west of the
   Cascade crest. The primary threats from this activity will be
   strong/damaging wind gusts as well as large hail. Storms may
   additionally impact ongoing wildfires in the region. A severe
   thunderstorm watch may be considered if convective trends warrant.

   ..Wendt/Thompson.. 09/17/2020

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

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

   LAT...LON   42632394 42842423 43632413 45042333 45372301 45332226
               44732170 43102205 42472249 42352339 42632394