Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 290935

Area Forecast Discussion
National Weather Service Cheyenne WY
335 AM MDT THU SEP 29 2016

.SHORT TERM...(Today through Saturday)
Issued at 335 AM MDT Thu Sep 29 2016

Satellite pix early this morning depict plume of sub-tropical
moisture streaming north/northeast from the Baja into southern
Wyoming. Regional radar confirm moisture advection in the way
of weak shower activity lifting north thru NW Colorado and
into southern Wyoming. Clouds have also been on the increase
across Carbon County this morning. The combination of increasing
moisture and lift associated with shortwave energy will be enough
for increasing precipitation chances across the Snowy/Sierra
Madre/Laramie Ranges and adjacent high plains/valleys thru the
day today. Progd instabilities are weak (SBCAPES of 100-400j/kg),
but should be enough for a few weak thunderstorms over
Carbon/Albany counties this afternoon. A few showers may linger
into the overnight hours over the hier terrain of the Snowy,
Sierra Madre and northern Laramie Ranges. Precip chances continue
into Friday afternoon/evening, even potentially spreading as far
east as Cheyenne by afternoon and Torrington/Scottsbluff Friday
evening. Sub-tropical plume shifts east bringing an end to any
precipitation chances Friday night and Saturday Morning. Low-
level convergence along the developing lee-side sfc pressure
trough will combine with a flattening ridge to spark some weak
afternoon convective chances over the southeast Wyoming mountains
Saturday. Temperatures will be persistent today through Saturday,
with highs averaging in the 70s across the eastern plains and 60s
to near 70 over lower elevations of Carbon/Albany Counties.

.LONG TERM...(Saturday through Wednesday)
Issued at 335 AM MDT Thu Sep 29 2016

Still looking for an upper low pressure system to move east across
the area late in the weekend through early next week bringing an
increased chance for precipitation to the area Sunday through
Tuesday. Still thinking there will be enough instability to get a
few thunderstorms on Sunday, with a chance of snow for elevations
above 7000 ft late Monday into Tuesday as the wrap around moisture
with the upper low transits east across the region. GFS is wetter
and colder for Tuesday whereas the ECMWF is drier and not at cold.
For this package we continue to carry a chance of snow in the
higher elevations late Monday through Tuesday night with small er
PoPs due to uncertainty for lower elevations to the east.


.AVIATION...(For the 12Z TAFS through 12Z Thursday night)
Issued at 250 AM MDT Thu Sep 29 2016

We will see some high level cloudiness move into the Rawlins,
Laramie and Cheyenne areas today...but otherwise expect VFR
category at all airports for the next 24 hours.


Issued at 335 AM MDT Thu Sep 29 2016

No fire weather concerns over the next week with relative humidity
values remaining well above critical thresholds. Aside from weak
shower/thunderstorm chances across higher elevations over these
next few days, expect coverage to be few and far between.
Temperatures will remain seasonally warm with highs in the 60s to
near 70 west and 70s to near 80 east. Cooler temperatures and
unsettled conditions return early next week as an area of low
pressure moves through the area.


.CYS Watches/Warnings/Advisories...



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