Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 202339 AAA

Area Forecast Discussion...UPDATED
National Weather Service Cheyenne WY
539 PM MDT Thu Apr 20 2017

.SHORT TERM...(Tonight through Saturday)
Issued at 223 PM MDT Thu Apr 20 2017

Clouds increasing over the CWA this afternoon with showers also
increasing gradually over and near the higher mtns. This in
response to digging upper shortwave now over the Pacific
northwest. This system will continue to drop southeast overnight
and close off an upper low over Colorado during the day Friday.
Rains and higher elevation snow will increase across mainly the
southwest half of the CWA overnight and continue across most of
the CWA Friday before tapering off Friday night. Main difficulty
will continue to be the level of accumulating snow later tonight
into Friday. Still appears that will be generally above about
7000 feet so current Winter Wx Advy looks good overall though the
start of the snow over the South Laramie Range may hold off until
later this evening. Some snow likely to fall as well later tonight
into Friday morning down to around 6000 feet or so but initial warm
ground and Sun angle likely to limit accumulations late tonight
and Friday. Winds modest and should not create much of a problem.
Much cooler over much of the CWA Friday given clouds and pcpn with
chilly conditions Friday night. System pulls away Friday night
and saturday allowing for warmer weather to begin its return on

.LONG TERM...(Saturday night through Thursday)
Issued at 223 PM MDT Thu Apr 20 2017

A warm and dry start to the extended forecast period w/broad upper
level ridging in place. Strong subsidence beneath the ridge should
preclude any risk for precipitation through Sunday evening. Expect
highs in the 60s and 70s with H7 temperatures of +5 to +7 C. GFS &
ECMWF both suggest a fast moving short-wave trough tracking across
the central Rockies on Sunday night/Monday. Jet energy is expected
to be fairly modest, but 700-300 hpa RH progs show sufficient mid/
high level moisture for scattered precipitation coverage. It looks
like the overall pattern will remain rather unsettled through much
of next week with numerous waves embedded w/in fast WNW flow aloft
through Thursday. Medium range models suggest a deepening low over
the western US mid to late week, which could have the potential to
bring widespread precipitation to the CWA.


.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 539 PM MDT Thu Apr 20 2017

Light rain becoming more widespread around Cheyenne and Laramie
with snow falling at higher elevations west of Cheyenne. Expect
snow levels to drop to near 6000 ft toward morning, so have LIFR
visibilities and ceilings in for Cheyenne and Laramie overnight
with IFR low ceilings to the east toward morning for Scottsbluff,
Sidney and Alliance with mostly light rain expected. Expect
activity to remain more showery around Rawlins overnight but do
think ceilings will also fall there overnight to IFR.
Precipitation will continue Laramie and points east through the
late morning before starting to taper off from the west in the


Issued at 223 PM MDT Thu Apr 20 2017

Wetting pcpn expected across much of the area tonight and Friday
with cooler temperatures. This will keep fire weather concerns nil
through at least the weekend.


WY...Winter Weather Advisory until 6 PM MDT Friday for WYZ112-114-116.



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