ZCZC SPCSWOMCD ALL
ACUS11 KWNS 270452 
SPC MCD 270452 
SDZ000-NDZ000-270645-

Mesoscale Discussion 0902
NWS Storm Prediction Center Norman OK
1152 PM CDT Tue Jun 26 2018

Areas affected...Parts of western and central SD

Concerning...Severe potential...Watch likely 

Valid 270452Z - 270645Z

Probability of Watch Issuance...80 percent

SUMMARY...An isolated severe risk in the short term is expected to
increase in coverage, with storms growing upscale into a
forward-propagating convective complex across central South Dakota
tonight with threat for damaging winds and hail.  A severe
thunderstorm watch is likely for parts of South Dakota.

DISCUSSION...Since 03-0330Z, mosaic radar imagery showed an increase
in storms and overall intensities along a surface boundary extending
from southwest ND into extreme southeast MT, with this broken band
of storms tracking to the southeast.  Forcing for ascent attendant
to a progressive shortwave trough, now moving into the western
Dakotas, appears to be aiding in this convective development, and
should result in strengthening southerly low-level winds across the
central High Plains into western and central SD through tonight to
early Wednesday morning.  A residual reservoir of very strong
instability residing across western and central SD will be fed into
the southern extent of the storm activity by the strengthening
low-level jet.  A 50-kt westerly midlevel jet accompanying the
progressive shortwave trough will maintain strong effective bulk
shear with vectors generally sustaining a linear structure through
the overnight period.  These factors support greater forecast
confidence in a scenario for an MCS producing a severe-weather
threat across parts of western and central SD through tonight.

..Peters/Edwards.. 06/27/2018

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

ATTN...WFO...FSD...ABR...BIS...UNR...

LAT...LON   45620331 45830260 45950047 45869974 44549916 43989899
            43409921 43070018 43140124 43320188 43890263 44450307
            45620331 

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