Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 250546
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1146 PM MDT Sun Sep 24 2017

.UPDATE...
Issued at 1143 PM MDT Sun Sep 24 2017

Snow has dissipated across the Snowy Range late this evening,
therefore the Winter Weather Advisory has been cancelled.

&&

.SHORT TERM...(This evening through Tuesday)
Issued at 259 PM MDT Sun Sep 24 2017

Tonight...Expect visibilities to slowly improve through the early
evening over the I-80 summit and foothills, thus have cancelled the
dense fog advisory, especially with rain expected to move into the
area overnight. A band of rain, with snow at mountain locations
expected to move across our counties of Wyoming this evening, so the
Winter Weather Advisory for the Snowy Range looks on track.
Precipitation chances should decrease somewhat after midnight in the
wake of the shortwave trough aloft passage. Still will see areas of
fog along and east of the Laramie Range with close temperature and
dewpoint spreads.

Monday...Upper trough still prevails overhead, though with some
clearing noted in the afternoon. Will likely see some scattered
showers develop in the afternoon with cool air aloft and adequate
low and mid level moisture. Warmer temperatures with somewhat less
cloud cover.

Monday night...Main trough aloft moves off to our east, though will
still likely see some cloud cover, with slow clearing from west to
east.

Tuesday...Flow aloft turns westerly with more sunshine and
moderating temperatures. No signs of lift along with limited
moisture, thus dry. For high temperatures, compromised between the
NAM and GFS MOS maximums.

.LONG TERM...(Tuesday night through Saturday)
Issued at 259 PM MDT Sun Sep 24 2017

The models are in good agreement at showing an upper low developing
in the vicinity of Arizona on Tuesday night after splitting off from
the main upper level flow. This low is progged to lift northeastward
on Thursday to near western Colorado. The best moisture and lift
will remain mostly south into Colorado, however could see some
shower chances return to areas near the Colorado Border, especially
the Sierra Madre and Snowy Ranges. While temps will moderate by
the middle of next week, they will still remain a few days below
average. Winds will be weak through Friday in the split flow
aloft. Better warming may occur by next weekend as the shortwave
trough moves east of the region with stronger and more zonal flow
aloft over the Intermountain West.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1143 PM MDT Sun Sep 24 2017

Poor aviation conditions to persist through at least 18z. Should
see enough dry for some category improvement during the afternoon,
however expect a return to IFR for many locations after 26/04z.
Main initial concern in with stratus/fog which will continue
blanketing the area overnight, resulting in IFR/LIFR CIGS & VSBYS.
Mountain obscurations will be a certainty for routes around the
area. Band of precip will gradually weaken and eventually
dissipate as it lifts across Panhandle sites through 12z. Do not
expect this precip to have appreciable impact on the already low
aviation conditions. Dry conditions anticipated Monday morning,
with a return to some isolated showers after 21z. KSNY stands the
best shot of seeing this precip activity. Confidence was less
elsewhere, so favored VCSH in these locales for now. Although
Monday night should feature one more night of low ceilings, drier
conditions are anticipated Tue-Fri.

&&

.FIRE WEATHER...
Issued at 259 PM MDT Sun Sep 24 2017

No concerns based on projected winds and humidities.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.

&&

$$

UPDATE...CAH
SHORT TERM...RUBIN
LONG TERM...ZF
AVIATION...CAH
FIRE WEATHER...RUBIN



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