Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 172300
SWOMCD
SPC MCD 172300
SDZ000-NEZ000-KSZ000-COZ000-180100-

Mesoscale Discussion 1517
NWS Storm Prediction Center Norman OK
0600 PM CDT Thu Aug 17 2017

Areas affected...Portions of southern SD...western/central
NE...northeastern CO...and northwestern KS

Concerning...Severe potential...Watch unlikely

Valid 172300Z - 180100Z

Probability of Watch Issuance...20 percent

SUMMARY...An isolated severe threat may persist through the evening,
with large hail and strong to damaging winds possible. Watch
issuance is unlikely.

DISCUSSION...Satellite imagery shows a low-amplitude shortwave
trough moving southeastward across the northern Plains this evening,
and a related weak surface low is present across the western
Dakotas. A lee trough extends southward from this low across the
northern/central High Plains. Isolated convection has recently
developed along the surface trough across southern SD and
southwestern NE. A narrow corridor of modified low-level moisture
exists to the east of this convection. Coupled with ample diurnal
heating and modestly steep mid-level lapse rates, this low-level
moisture is supporting mostly weak to locally moderate instability
(MLCAPE 500-1500 J/kg). Mid-level west-northwesterly flow of 30-35
kt and a veering low-level wind profile is encouraging similar
values of effective bulk shear, which may allow for some updraft
organization. Multicell clusters should be the dominant storm mode
as a southerly low-level jet strengthens some this evening, but a
few marginal supercells cannot be ruled out either. Isolated
instances of large hail and strong to locally damaging winds may
occur with the most organized storms. Current expectations are for
the severe threat to remain quite isolated through the evening
hours, and watch issuance appears unlikely.

..Gleason/Edwards.. 08/17/2017

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

ATTN...WFO...FSD...ABR...GID...LBF...UNR...GLD...BOU...CYS...

LAT...LON   43070256 43770112 43870002 43769896 43239881 40799988
            38600120 38920306 39500339 43070256



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