Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 241718

Area Forecast Discussion
National Weather Service Riverton WY
1118 AM MDT Sat Mar 24 2018

.SHORT TERM...Today through Monday night
Issued at 247 AM MDT Sat Mar 24 2018

A Pacific low is moving into the Northwestern States today which
will propagate a quick moving shortwave across our western areas.
Snow accumulations will be below advisory levels in both the western
mountains and valleys though the Tetons may get close. Sunday
morning the 700mb low arrives over Southwest WY. This will begin to
spread precip further east of the divide, starting as rain for
central WY and to the north and east areas. As the low pushes
northeastward across the state Sunday night snow occurs in the
Wind River and Big Horn Basins through Johnson and Natrona
Counties. Models have indicated that the low will slow a bit
before leaving the state which could bring significant snow
amounts to the Bighorn Mountains and Johnson County so a Winter
Weather Watch has been issued. Snow will continue through the day
Monday before tapering of Monday evening.

.LONG TERM...Tuesday through Saturday
Issued at 247 AM MDT Sat Mar 24 2018

Tuesday looks dry and cool for the region with highs in the 30s and
40s. Isolated afternoon snow showers in the NW WY mountains cannot
be ruled out. The next weather system impacts the north Tue night
with some light snow. The precip develops over the central and south
Wed afternoon into Wed night. Precip will a mix of rain and snow
here. Snow pellet showers cannot be ruled out as well. High temps
Wed in the 30s and 40s with temps falling into the 30s in the
central zones in the afternoon as the cold air pushes southward.
Snow showers Wed night, decreasing after midnight from north to
south. Thursday will see dry weather for most places with lingering
snow showers in the northern mountains and rain or snow showers
across parts of Johnson county. High temps Thursday in the 40s to
around 50. Friday now looks dry and milder over the region with
highs in the upper 40s to upper 50s. Next Saturday could see some
rain and snow return to the NW WY mountains and the northern Bighorn
mountains. The GFS and ECMWF models show this moisture increase
ahead of a weather system that may move into WY next Saturday night.
Dry weather elsewhere next Saturday with breezy to windy areas and
highs in the 50s to lower 60s.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1059 AM MDT Sat Mar 24 2018

West of the Divide...KBPI/KJAC/KPNA/KRKS Routes

Clouds have increased across the western mountains this
morning, as an area of snow showers encroaches from E ID. Bands
of snow have already brought IFR conditions to KJAC. Expect low
MVFR/IFR conditions to KJAC through 21-22Z, then VCSH after 00Z. A
cold front will progress across the rest of the area after 21Z,
will SHSN developing KBPI/KPNA by 00Z, and KRKS 03Z-06Z. Another
round of sct-nmrs MVFR/IFR snow showers is expected to move into
the west, vicinity and north of a KEVW-KPNA line, 08Z- 12Z

East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Routes

VFR conditions are expected to prevail through 00Z Sunday.
Surface S to SW winds will increase to 15-25 knots across much of
the area, with higher speeds from vicinity 50NE KRKS-KCPR. A cold
front will push south across northern Wyoming Saturday evening
with scattered MVFR, isolated IFR, shsnra developing primarily
vicinity and south of a KLND-KRIW line. Areas of MVFR/IFR ceilings
and light snow are expected to develop behind the cold front
along and east of the Bighorn Mtns to 60SM west of KCPR 06Z-12Z
Sunday. This activity will become confined along and east of the
Bighorn Mtns after 12Z Sunday.


Issued AT 247 AM MDT Sat Mar 24 2018

An upper level shortwave will bring snow to the western mountains
and valleys today, but will leave east of the divide warm and dry
until later this evening. Precipitation will be prevalent from
tonight through the weekend across the forecast area. Gusty
southwest winds will focus mainly in the mountains this morning
before moving down to lower elevations in the afternoon. Winds
across the area will slow considerably once evening arrives.


Winter Storm Watch from Sunday evening through Monday afternoon
for WYZ008>011.



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