Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 221429
SWOMCD
SPC MCD 221428
IAZ000-MNZ000-221600-

Mesoscale Discussion 1120
NWS Storm Prediction Center Norman OK
0928 AM CDT Thu Jun 22 2017

Areas affected...Northern IA...Southern MN

Concerning...Severe potential...Watch unlikely

Valid 221428Z - 221600Z

Probability of Watch Issuance...20 percent

SUMMARY...A small convective system will pose a threat of isolated
damaging wind and hail through the morning. At this time, watch
issuance is considered unlikely.

DISCUSSION...A small convective system has recently evolved over
southern MN and far northern IA. This system is being supported by
moderate MUCAPE (1250-2000 J/kg per recent mesoanalyses) and
sufficient effective shear to support some convective organization.
This convection is expected to persist through the morning as it
moves along and just north of a weak surface boundary over northern
IA, with some reorganization possible as convection redevelops
immediately downstream.

Rather strong pressure rises noted immediately upstream indicate
that the system has become somewhat organized. However, the severity
of the system may tend to remain somewhat limited. While instability
is sufficient for hail, a primarily linear or cluster convective
mode will not be favorable. Meanwhile, the elevated nature of the
convection and lack of substantial heating downstream (due to
ongoing elevated convection over northeast IA) will likely temper
the severe wind threat to some extent. For these reasons, watch
issuance is considered unlikely, though a few instances of damaging
wind and/or marginally severe hail will be possible through the
morning as the system moves eastward.

..Dean/Guyer.. 06/22/2017

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

ATTN...WFO...ARX...MPX...DMX...FSD...

LAT...LON   44139468 44199314 44179216 43729152 43359134 42979198
            42919256 42779329 42879430 43299517 43739475 44139468




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