Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 162323

Area Forecast Discussion
National Weather Service Cheyenne WY
523 PM MDT Wed Aug 16 2017

.SHORT TERM...(This evening through Friday night)
Issued at 250 PM MDT Wed Aug 16 2017

Current watervapor and visible satellite loop shows the upper
level trough axis exiting Wyoming to the east early this afternoon
as it moves into central South Dakota and Nebraska. Some low
clouds and sprinkles are possible across the western Nebraska
panhandle through this afternoon before drier and warmer air aloft
moves eastward. This warmer air aloft has made it into southeast
Wyoming and is capping most of the convection trying to develop
across the mountains. Lowered POP across the mountains this
afternoon and into this evening, but can not rule out a stray
thunder shower early this evening before sunset. Overnight lows
will be relatively cool for August with readings generally in the
40`s to low 50`s.

Warmer and generally drier conditions are expected for Thursday
and Friday with typical mid-late August conditions. Models do show
a quick moving upper level disturbance, embedded in northwest
flow aloft, moving across Wyoming and Montana during Thursday.
This feature may provide enough cool air aloft for afternoon
showers and thunderstorms across the mountains and areas east of
the Laramie Range across the plains. Confidence is pretty low
however as surface winds will be westerly with dewpoints in the
30`s and 40`s. Otherwise, chance of precipitation on Friday will
be nearly zero as warm/dry air aloft moves into the area from the
west. High temperatures will be seasonable and in the 80`s across
most of the region to near 90 over the lower elevations of
western Nebraska.

.LONG TERM...Saturday through Tuesday

We expect quasi-zonal flow aloft to prevail across the CWA through
most of the extended period, along w/ a deepening upper low across
the western CONUS. Models suggest very little in the way of energy
traversing the flow, so overall expect dry conditions w/ showers &
thunderstorms mainly over the higher terrain. It continues to be a
tricky cloud forecast for Eclipse Day (Monday) with west-southwest
flow aloft and decent H7-H3 moisture. There are still considerable
differences though in the RH fields, so opted to maintain a partly
cloudy forecast for most areas. Daytime high temperatures thru the
period will average in the 80s, with a few 90s possible across the
western Nebraska Panhandle.


.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 521 PM MDT Wed Aug 16 2017

VFR. Wind gusting 20 to 25 knots after 15Z Thursday, except at
Chadron and Scottsbluff.


Issued at 155 PM MDT Wed Aug 16 2017

Fire Weather concerns will remain low late this week and into
next weekend due to recent rainfall and light winds. Other
than a few stray thunderstorms each afternoon near the mountains,
drier conditions are expected for the rest of the week with
little to no precipitation. Relative humidities will trend lower
Thursday and Friday with values in the teens to low 20`s across
southeast Wyoming by this weekend.




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