ZCZC SPCSWOMCD ALL
ACUS11 KWNS 212254 
SPC MCD 212254 
ORZ000-220100-

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 

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