Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 132127
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
227 PM MST Sat Jan 13 2018

.SHORT TERM...(This evening through Tuesday)
Issued at 146 PM MST Sat Jan 13 2018

Northwest flow aloft with limited moisture will keep some clouds
and light snow over the north and west tonight into Sunday.
Snowfall is expected to be light and spotty. Temperatures will be
cool with clearing in the west and south Sunday night and Monday.
A Canadian cold front leading ahead of an Arctic cold front will
bring light snow south across the north and east into central basins
Sunday night and Monday.  The precipitation and moisture will thin
out and dissipate Monday afternoon and evening with clearing leaving
colder temperatures and stronger inversions over the area especially
east of the Continental Divide.

.LONG TERM...(Tuesday night through Saturday)
Issued at 146 PM MST Sat Jan 13 2018

Ridge axis will be breaking down at the start of the forecast
period, as a trough splits and undercuts southern portions of the
ridge. This trough will bring isolated to scattered snow to the far
west Tuesday night into Wednesday. SW flow will then quickly develop
Thursday, as a longwave trough makes its onshore over the PACNW. As
pointed out by the previous shift, winds will start to increase
ahead of this system in the mountains, Wind Corridor and eastern
slopes of the foothills, with some strong wind potential for the
normal W-SE favored areas. Although there remains good dynamics with
this system initially, most of the energy is progged to remain well
to the south over the Four Corners Friday. The ECMWF does resolve a
H5 low over eastern WY by 12Z Saturday and a H7 low over the NE
Panhandle. At this point, this looks to be the best chance for snow
across the area. If the system were to slowdown at any point, this
could impact portions of Natrona and possibly eastern Sweetwater
County. The GFS however, is less cohesive and develops the H5 low
over S CO/TX Panhandle. Kept PoPs generally scattered across the
area Friday/Friday night, as a result. Another ridge will build over
the region through the weekend, with warm advection snows possible
for the western mountains.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday)
Issued at 146 PM MST Sat Jan 13 2018

West of the Continental Divide...KJAC, KBPI, KPNA and KRKS

Higher mountains will remain mostly obscured through for a couple
more hours, before clearing this evening. Areas of IFR/MVFR ceilings
will likely seep in from eastern Idaho to vicinity KJAC- KBPI
overnight tonight. These conditions are expected to continue through
the rest of the TAF period at KJAC. LLWS will be marginal tonight
vicinity KPNA. Otherwise, mid to high level clouds will reenter
after 18Z Sunday.

East of the Continental Divide...KCPR, KCOD, KRIW, KLND, and KWRL

-SN is ending vicinity and north of a KPOY-KBYG line, however the
Bighorn Range and northern Absaroka Range remain mostly obscured.
VFR conditions are expected to prevail through the period. LLWS will
develop this evening at KWRL and subside at KRIW. Mid to high level
clouds will reenter the area in the NW flow between 15Z-18Z Sunday,
from KCOD to KCPR. These clouds will progress southward through the
afternoon Sunday. Marginal MVFR clouds will begin to impact the
Bighorn Range by 21Z Sunday, as a cold front begins moving
southward. These clouds will extend from a KPOY-KDGW line by 00Z
Monday.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for
the latest information on icing and turbulence forecasts.

&&

.FIRE WEATHER...
Issued AT 146 PM MST Sat Jan 13 2018

Northwest flow aloft with limited moisture will keep some clouds
and light snow over the north and west tonight into Sunday.
Snowfall is expected to be light and spotty. Temperatures will be
cool with clearing in the west and south Sunday night and Monday.
A Canadian cold front leading ahead of an Arctic cold front will
bring light snow south across the north and east into central basins
Sunday night and Monday.  The precipitation and moisture will thin
out and dissipate Monday afternoon and evening with clearing leaving
colder temperatures and stronger inversions over the area especially
east of the Continental Divide.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Baker
LONG TERM...LaVoie
AVIATION...LaVoie
FIRE WEATHER...Baker


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