Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 201726

Area Forecast Discussion
National Weather Service Cheyenne WY
1126 AM MDT TUE SEP 20 2016

.SHORT TERM...(Today through Thursday)
Issued at 227 AM MDT Tue Sep 20 2016

Today...Another quite warm day on tap based on thickness and 700 mb
temperature changes, and expect most locations to be near or
slightly warmer than highs on Monday. Continued dry with limited low
and mid level moisture.

Tonight...Another relatively mild night in this warmer than normal

Wednesday...A weak cold front or surface trough will drift southward
across our counties in the afternoon, and with progged 1000-500 mb
thicknesses and 700 mb temperatures, expect cooler temperatures,
though still above normal at most locations. Continued dry with
limited low and mid level moisture.

Wednesday night...Cooler night in the drier and cooler airmass.
Boundary layer progs from the NAM suggest near saturation east of I-
25 and thus have added mention of areas of fog east of a Lusk to
Pine Bluffs line which meshes well with the areas of fog over our
neighboring counties in Rapid City`s forecast area.

Thursday...Potent trough aloft nudges closer with the cold frontal
boundary moving into western Wyoming in the afternoon. Isolated to
scattered showers, along with isolated thunderstorms, expected to
move into our western counties in the afternoon, mainly west of a
Douglas to Laramie line. Temperatures will cool even more with
additional cloud cover and low level upslope southeast winds.

.LONG TERM...(Thursday Night through Monday)
Issued at 227 AM MDT Tue Sep 20 2016

It still appears the best forcing will be largely north and west
of southeast WY through Thurs night with the closed upper low
across northern Utah. However, have 20-40 percent pops through the
night across the northwestern half of the CWA. Both the GFS and
ECMWF show widespread precip developing across the plains by Fri
aftn/evening along the cold front. Went with 40-50 percent pops
for now. Thunderstorms will be possible through the evening with
the cooling aloft/dynamic lift. Cooler temps will occur over the
weekend with 700 mb temps falling to around 0C. It will be cloudy
for much of Saturday as the upper trough hangs over the region.
The models continue to indicate drying by Sunday and into early
next week.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday morning)
Issued at 1126 AM MDT Tue Sep 20 2016

VFR conditions through the TAF period with high clouds
streaming across the region.


Issued at 227 AM MDT Tue Sep 20 2016

Will need to closely monitor conditions this afternoon as
humidities will fall into the 10 to 15 percent range with gusty
winds across Carbon county, though at this time, it appears most
locations will see winds remaining below 25 mph. Conditions will
improve the next several days with much increased afternoon


.CYS Watches/Warnings/Advisories...


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