Severe Storm Outlook Narrative (AC)
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ACUS11 KWNS 271922
SWOMCD
SPC MCD 271921
WYZ000-MTZ000-IDZ000-UTZ000-272045-

Mesoscale Discussion 1162
NWS Storm Prediction Center Norman OK
0221 PM CDT Tue Jun 27 2017

Areas affected...Eastern Idaho...central and western Wyoming...and
southern Montana

Concerning...Severe potential...Watch unlikely

Valid 271921Z - 272045Z

Probability of Watch Issuance...20 percent

SUMMARY...Thunderstorms will continue/develop across portions of
eastern Idaho, central and western Wyoming, and southern Montana
through the afternoon. These thunderstorms will move east. Small
hail, potentially up to an inch, and gusty thunderstorm winds will
be the primary threat.

DISCUSSION...Thunderstorms ongoing/developing across eastern Idaho
and western Wyoming and will move east into a slowly increasingly
unstable environment. Additional thunderstorms should develop ahead
of the previously mentioned ongoing thunderstorms.

These thunderstorms will continue to develop within a large-scale
environment characterized by deep-layer shear (on the order of 40
knots) and steepening mid-level lapse rates (to between 7-8 C/km).
Despite the steepening mid-level lapse rates, modest low-level
moisture (surface dew points in the mid-30s to mid-40s F) and
surface temperatures only in the 70s and 80s F have contributed to
modest most-unstable CAPE values between 500-1000 J/kg.

The presence of large temperature-dew point spreads may support
strong, gusty thunderstorm outflow that could be capable of isolated
wind damage. Additionally, the modest CAPE and sufficient deep-layer
shear may support an isolated large-hail threat with the strongest
thunderstorm cores. The anticipated lack of thunderstorm
organization and limited nature of the threat, should preclude the
need for a watch.

..Marsh/Guyer.. 06/27/2017

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

ATTN...WFO...UNR...CYS...BYZ...RIW...TFX...SLC...PIH...MSO...

LAT...LON   45800980 45320708 43590601 41850751 41630915 41701079
            42021167 43541405 44791388 45301310 45800980




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