Area Forecast Discussion
Issued by NWS Riverton, WY

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

000
FXUS65 KRIW 140633
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1133 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 06Z TAFS through 06Z Sunday night)
Issued at 1132 PM MST Sat Jan 13 2018

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

Patchy fog and areas MVFR/IFR ceilings are expected to continue to
develop vicinity KJAC through sunrise Sunday.  Further south,
confidence was lower to go beyond VCFG at KBPI where lower levels
were drier.  Lower ceilings should lift and scatter out over the
Jackson Valley by afternoon, but may briefly return Sunday evening.
A strengthening downslope NNE flow should hinder fog/low cloud
formation vicinity KJAC after 06z Monday.  An Arctic cold front
plunging south along the east slopes of the Divide will push across
the Interstate 80 corridor, KRKS, 06z-09z Monday with areas of MVFR
ceilings likely behind the front.  Confidence was not high enough to
prevail this ceilings as far west as KRKS on this issuance with
differing scenarios still depicted by model guidance.

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

Mid-level ceilings FL110-130 vicinity and east of a KPOY-KCPR line
will dissipate overnight as an upper level disturbance exits across
the Plains.  VFR conditions are expected to prevail through 21z
Sunday.  An Arctic cold front will then back south and west into the
area, spreading primarily low MVFR ceilings and visibilities in -SN
to a vicinity KCOD-KCPR line by 03z Monday, and against the east
slopes of the Divide (KRIW-KLND) 06z-09z Monday. Mountains will
become increasingly obscured through Sunday evening.  These
conditions will persist across the area through 12z Monday.

&&

.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...Meunier
FIRE WEATHER...Baker



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.