Severe Storm Outlook Narrative (AC)
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ACUS11 KWNS 160634
SPC MCD 160633

Mesoscale Discussion 1648
NWS Storm Prediction Center Norman OK
0133 AM CDT Sat Sep 16 2017

Areas affected...Parts of west central Nebraska

Concerning...Severe potential...Watch unlikely

Valid 160633Z - 160830Z

Probability of Watch Issuance...5 percent

SUMMARY...Thunderstorms may continue to be accompanied by the risk
for marginally severe hail across parts of west central Nebraska
another couple of hours, before diminishing toward daybreak.

DISCUSSION...An area of convection, with scattered embedded vigorous
thunderstorm along its leading edge, near/southwest of Sidney into
areas west of Valentine, is elevated to the cool side of a southward
advancing cold front.  It appears based around 700 mb, within
forcing for ascent associated with warm advection, which the latest
Rapid Refresh indicates will continue spreading east/northeastward
tonight.  Guidance indicates that CAPE for parcels reaching levels
of free convection is generally weak, on the order of 500 J/kg, but
strong vertical shear in the cloud bearing layer has contributed to
support for at least occasional marginally severe hail in strongest
storms.  This may progress into areas west through north of North
Platte, through the Ainsworth vicinity, between now and 09-11Z,
before convection begins to diminish in the presence of weaker
destabilization.  Based on the latest forecast soundings, the
potential for strong surface gusts seems minimal, at least via
strong downdrafts/downward momentum transfer.

..Kerr/Grams.. 09/16/2017

...Please see for graphic product...


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