Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 240944

Area Forecast Discussion
National Weather Service Cheyenne WY
344 AM MDT SAT SEP 24 2016

.SHORT TERM...(Today through Sunday night)
Issued at 255 AM MDT Sat Sep 24 2016

The main concern today will be how long the precipitation will
linger across the northern portions of the forecast area today.

Latest radar loop was showing the precipitation continuing to lift
north to northern Wyoming. This precip. caused quite the show
overnight especially between Rawlins and the I-80 Summit. In fact,
the I-80 summit received nearly 4 inches of snow with Laramie
receiving 2 inches. This precip was beginning to dissipate in
response to a dry slot to the northeast of this precip. Not
completely sure if this trend will continue, since there appears
to be more radar returns developing across southern Wyoming as the
dry slot continues to fill in across Colorado. Latest water vapor
loop was showing some signs of cyclogenesis taking place across
northwest Wyoming. However, the bulk of the jet energy was lifting
north into the northern plains. The mid level flow was trying to
back to southeast and forming a weak trowal over northwest
wyoming. On the back side of this upper level low in northwest
Wyoming there is significant potential vorticity anomaly and jet
energy diving south. This potential vorticity anomaly should help
kick this upper level low east during the course of the day.
However, I am not seeing any signs of the moisture kicking out of
the picture yet. As a result, we may see the development of more
scattered showers this afternoon across southeast Wyoming. We did
lower temperatures a bit compared to the previous forecast since
the ground temperatures will be a bit cooler from the precip.

A chilly night is in store for much of Wyoming as the surface high
settles over the area. In fact, Laramie and Rawlins may drop below
freezing with rest of the area ranging from 35 to 40. Day shift
may want to look at the potential for frost headlines in portions
east of the Laramie Range.

Sunday-Sunday night:
Cool temperatures will remain in tact on Sunday as the surface high
slowly drifts east into the Nebraska Panhandle. Could be a bit
breezy in the panhandle on Sunday afternoon. Otherwise, the
sunshine will be prevalent with afternoon highs ranging from 55 to
65. Overnight lows will once again be quite chilly with lows
mainly in the 30s.

.LONG TERM...(Monday through Friday)
Issued at 255 AM MDT Sat Sep 24 2016

Monday...Decent warming trend on tap as the ridge aloft strengthens
and the airmass moderates. Based on thicknesses and 700 mb
temperatures near 8 Celsius, expect high temperatures from the mid
60s to lower 70s.

Tuesday...Another dry and mild early Autumn day with the ridge aloft
overhead. Sticking close to guidance maximum temperatures based on
progged 700 mb temperatures.

Wednesday...Will likely see some increase in middle and high
cloudiness ahead of the next approaching slow moving shortwave over
the Great Basin states. Continued mild per thicknesses and 700 mb

Thursday...A little bit cooler as cloud cover increases with a weak
shortwave approaching from western Wyoming and western Colorado.
Perhaps enough moisture for isolated mountain showers in the

Friday...Weak southwest flow aloft continues and with limited low
and mid level moisture, no precipitation expected. Continued mild
based on the expected 700 mb temperatures.


.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1013 PM MDT Fri Sep 23 2016

Showers will continue overnight, producing occasional MVFR cig/vis.
The mountains will be obscured by low cigs and snow showers. Gusty
northwest to west winds 25-35 kt will continue as well. Brief -TSRA
will impact the western Nebraska terminals until 08Z. Cig/vis improve
to VFR east of the Laramie Range by morning, with MVFR cig persisting
at RWL thru the day. Scattered showers will be possible west of the
Laramie Range Saturday with VCSH at RWL and LAR. West winds will gust
25-30 kt Saturday.


Issued at 255 AM MDT Sat Sep 24 2016

Drier air is expected to filter into the Nebraska Panhandle today
as the upper level trof lifts into the Northern Plains. This area
will receive strong west-northwest winds this afternoon at speeds
of 15 to 25 mph with some gusts to 35 mph. Relative humidites will
also be quite low in the panhandle this afternoon with values
possibly dropping to 20 to 25 percent. Meanwhile, southeast
Wyoming may see the redevelopment of more scattered showers this
afternoon. The threat for critical fire weather conditions will be
quite low from Sunday through the middle of next week due to light


.CYS Watches/Warnings/Advisories...
WY...Winter Weather Advisory until 3 AM MDT early this morning for



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