Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 292100

Area Forecast Discussion
National Weather Service Cheyenne WY
300 PM MDT Thu Sep 29 2016

.SHORT TERM...(This evening through Saturday night)
Issued at 300 PM MDT Thu Sep 29 2016

Early afternoon water vapor loop showed a large plume of subtropical
moisture streaming northward from the Four Corners into Wyoming and
Colorado. Large surface ridge encompassed the Great Plains, with a
trough along the lee of the Front Range. South-southeast winds were
gusting to 25-35 mph across the plains, with southwest winds gusting
to 25 mph west of the Laramie Range. Widely scattered showers and
a few thunderstorms were spreading north from western Colorado into
south/central Wyoming. The majority of the shower activity will be
confined west of the Laramie range through tonight.

Friday will be somewhat unsettled with a few weak waves embedded in
the southwest flow aloft triggering scattered showers/isolated
thunderstorms across southeast Wyoming, mainly over the mountains.
Convection will linger into Friday evening before ending. It will be
unseasonably mild with highs in the 60s and 70s, with 40s and 50s for
the mountains. Saturday will be almost a carbon copy of Friday, with
high temperatures a few degrees warmer for the plains. Afternoon and
evening convection will be confined to the southeast Wyoming mountains.

.LONG TERM...(Sunday through Thursday)
Issued at 300 PM MDT Thu Sep 29 2016

Mild conditions will remain across the CWA Sunday through Monday
in southwesterly upper flow ahead of an upper trough/low that will
move onshore over the west coast Sunday and over the western CONUS
Monday. Minor impulses moving out ahead of this system will bring
a chance for showers and a few storms to the CWA both days. The
Tuesday through Thursday forecast becomes somewhat problematic
depending on the track and speed of the upper system. The GFS is
deeper and slower with the upper low, progressing it across Colorado
Tuesday and into S. Dakota by late Weds while the EC is a little
weaker and farther north with the track. This will impact where
the better pcpn will fall with the GFS solution quite a bit wetter
for the CWA. For now will lean a little towards the GFS given
better ensemble support. A cold front looks to pass across later
Monday boding for cool and moist conditions Tuesday and Weds. Some
mtn snows look likely. Nudged temps somewhat below guidance
Tuesday and Weds given the expected lower thicknesses and ample
cloud cover along with pcpn. Thursday should be dry and milder
with the system departing to the northeast.


.AVIATION...(For the 18Z TAFS through 18Z Friday morning)
Issued at 1122 AM MDT Thu Sep 29 2016

VFR expected through the period.  Some mainly mid and high clouds
affecting mainly KRWL and KLAR with widely sctd showers and a few
tstms in that area as well.


Issued at 220 PM MDT Thu Sep 29 2016

No fire weather concerns expected through the middle of next week
with minimum humidities above critical thresholds. There will be
scattered showers and isolated thunderstorms for much of southeast
wyoming, mainly the higher elevations. Temperatures will be mild
to warm the next few days with highs in the 60s and 70s. Much
cooler temperatures and better chances for precipitation arrive
early next week with the passage of a low pressure system and cold




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