ZCZC SPCSWOMCD ALL
ACUS11 KWNS 272055 
SPC MCD 272055 
NDZ000-SDZ000-MTZ000-WYZ000-272300-

Mesoscale Discussion 1618
NWS Storm Prediction Center Norman OK
0355 PM CDT Fri Aug 27 2021

Areas affected...Northern High Plains

Concerning...Severe potential...Watch possible 

Valid 272055Z - 272300Z

Probability of Watch Issuance...40 percent

SUMMARY...Isolated thunderstorm development is possible late this
afternoon into early evening. The strongest storms will be capable
of large hail and locally severe wind gusts.

DISCUSSION...An mid/upper-level trough is moving across Montana this
afternoon. Multiple vorticity maxima are evident on WV imagery
within the larger-scale trough, but a lobe of ascent appears to
moving across eastern MT, in conjunction with a weak surface
boundary, and gradually deepening cumulus is noted across southeast
MT. While surface temperatures are not particularly warm, relatively
cool midlevel temperatures are supporting SBCAPE of 750-1500 J/kg
(per recent mesoanalyses), with weakening SBCINH. Effective shear is
generally 30-40 kt across the region, with locally higher values
across northwest SD/southwest ND/southeast MT, where surface winds
are locally backed. 

Isolated thunderstorm development is expected sometime late this
afternoon/early evening, with the most likely area across northwest
SD/southwest ND, where somewhat greater surface confluence is noted.
Long hodographs will favor a conditional potential for supercells,
with large hail and locally severe wind gusts the primary threats.
The need for a watch remains uncertain at this time, due to
potentially sparse storm coverage.

..Dean/Dial.. 08/27/2021

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

ATTN...WFO...BIS...UNR...BYZ...GGW...

LAT...LON   44660394 44830497 45350510 45720519 47670537 48440524
            48730484 48760423 48710344 48680288 48540224 46650207
            45980205 45470208 45070232 44840272 44680310 44680335
            44660394 

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