ZCZC SPCSWOMCD ALL
ACUS11 KWNS 052027 
SPC MCD 052027 
MTZ000-WYZ000-052230-

Mesoscale Discussion 0855
NWS Storm Prediction Center Norman OK
0327 PM CDT Sat Jun 05 2021

Areas affected...the south-central Montana/northwestern Wyoming
vicinity

Concerning...Severe potential...Watch possible 

Valid 052027Z - 052230Z

Probability of Watch Issuance...40 percent

SUMMARY...Gradually increasing convection over the south-central
Montana vicinity will pose a risk for very isolated, strong wind
gusts.  Need for potential WW remains uncertain.

DISCUSSION...Afternoon heating/mixing of a marginally moist boundary
layer has led to a general decrease surface dewpoints across the
region.  Still, gradual destabilization is ongoing, with mixed-layer
CAPE now around 500 J/kg per objective analyses over portions of
south-central Montana near and west of Billings.  

TCU/CB development is ongoing over the higher terrain of
southwestern Montana, with a few stronger updrafts now spreading
into lower elevation areas.  Activity remain isolated however, with
any potential for gusty winds largely dependent upon evaporative
assistance within the dry/well-mixed boundary layer.

With time, greater wind risk would likely be contingent upon
clustering/upscale growth of convection, and with limited
instability with eastward/northeastward extent into eastern Montana,
coverage/intensity of convection remains uncertain, despite ample
deep-layer shear supported by enhanced southwesterly mid-level flow
atop the region.

..Goss/Guyer.. 06/05/2021

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

ATTN...WFO...BYZ...GGW...RIW...TFX...

LAT...LON   44971138 45381155 46671022 47060916 46950712 46100688
            44910864 44880845 44301010 44971138 

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