ZCZC SPCSWOMCD ALL
ACUS11 KWNS 050011 
SPC MCD 050011 
SDZ000-NDZ000-MTZ000-WYZ000-050215-

Mesoscale Discussion 1152
NWS Storm Prediction Center Norman OK
0711 PM CDT Sun Jul 04 2021

Areas affected...Southeast Montana...far Northeast Wyoming...and far
Northwest South Dakota

Concerning...Severe potential...Watch unlikely 

Valid 050011Z - 050215Z

Probability of Watch Issuance...5 percent

SUMMARY...Storms may become more organized this evening, posing an
isolated wind/hail threat. Watch issuance unlikely.

DISCUSSION...Regional radar shows a cluster of somewhat disorganized
but marginally intense storms over southeast portions of Montana.
Strong diabatic heating has resulting in hot surface temperatures
into the mid 90s F, yielding strong low-level lapse rates. Weak
easterly/upslope flow has allowed surface dew point temperatures to
rise to near 50 F in proximity to the ongoing convection. The large
temperature/dew point spread is resulting in inverted-v soundings,
with weak instability (MLCAPE approaching 500 J/kg).

Despite the weak low-level easterly flow, amid marginal westerly
flow aloft, deep-layer shear remains rather weak (effective shear
perhaps near 20 kt). However, forecast soundings indicate some
potential for an increase in effective shear throughout the evening,
perhaps approaching 30-35 kt by 03z, as low-level southeasterly flow
increases. Thus, the ongoing convection may become a bit more
organized if it can persist for a few more hours. Should this occur,
storms will pose a threat for strong outflow wind gusts and severe
hail. At this time, the threat is expected to remain fairly
isolated/brief, and thus, watch issuance is not expected.

..Karstens/Hart.. 07/05/2021

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

ATTN...WFO...BIS...UNR...BYZ...RIW...

LAT...LON   44020469 44340601 44720729 45620728 46140637 46210441
            45760324 44670362 44020469 

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