Severe Storm Outlook Narrative (AC)
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000
ACUS01 KWNS 280040
SWODY1
SPC AC 280038

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0738 PM CDT Thu Jul 27 2017

Valid 280100Z - 281200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
WESTERN NEBRASKA...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL AND NORTHERN HIGH PLAINS...

...SUMMARY...
Isolated severe hail and damaging wind gusts will be possible early
this evening across parts of western Nebraska and far northeast
Colorado. Marginally severe storms will also be possible across
parts of the central and northern High Plains this evening.

...Central and Northern High Plains...
Water vapor imagery shows a subtle upper-level ridge over the
central Rockies with a minor shortwave trough moving into the High
Plains. At the surface, a trough of low pressure is located from
southeast Montana extending south-southeastward into northeastern
Colorado. Scattered thunderstorms are ongoing along and to the east
of the surface trough. Upslope flow is in place to the east of the
surface trough with surface dewpoints in western Nebraska and
northeast Colorado in the lower to mid 60s F. This is contributing
to a small pocket of moderate instability in western Nebraska where
the RAP is estimating MLCAPE in the 1000 to 1200 J/Kg range. In
addition, regional WSR-88D VWPs show 0-6 km shear of 40 to 45 kt
suggesting that a severe threat will be possible for a few more
hours this evening. Isolated large hail and wind damage will be the
primary threats with storms that rotate. A marginal severe threat
will exist from southeast Montana southward across eastern Wyoming
into northern Colorado where instability is generally weaker than in
areas to the east.

..Broyles.. 07/28/2017

$$



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