Mesoscale Discussion 1057
   NWS Storm Prediction Center Norman OK
   0554 PM CDT Mon Jun 21 2021

   Areas affected...Southern to central Oregon

   Concerning...Severe potential...Watch unlikely 

   Valid 212254Z - 220100Z

   Probability of Watch Issuance...5 percent

   SUMMARY...Isolated thunderstorms may pose a risk for hail and
   damaging winds this evening ahead of an approaching upper-level
   wave. A watch is not expected.

   DISCUSSION...A few lightning strikes have been noted in GLM data
   within a slowly deepening cluster of cumulus across south-central
   OR. Water vapor imagery also hints at deeper convective development
   within this cluster ahead of an approaching mid-level vorticity
   maximum. Dewpoints in the low to mid 40s and diurnal warming into
   the 90s have been sufficient to increase MUCAPE values into the
   250-500 J/kg range (with a pocket of 500-1000 J/kg MUCAPE noted in
   recent analyses). Although some inhibition remains in place,
   increasing lift ahead of the wave combined with orographic ascent
   should support isolated thunderstorms during the early evening
   hours. Increasing deep-layer flow will augment effective bulk shear
   values to near 30-35 knots within the zone of instability, which may
   aid in storm organization and support at least a low-end hail
   threat. Additionally, high dewpoint depressions are noted and are
   indicative of a dry, well-mixed boundary layer that may allow for
   damaging wind gusts. Given the isolated nature of this threat, a
   watch is not expected.

   ..Moore/Grams.. 06/21/2021

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

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

   LAT...LON   42062134 42292202 43442247 44362242 44832145 44882062
               44601991 44021965 42711909 42101919 42062134