Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 250559
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1059 PM MST Sat Feb 24 2018

.SHORT TERM...(This evening through Tuesday)
Issued at 239 PM MST Sat Feb 24 2018

Periods of light snow, occasionally moderate will occur across
western Wyoming through Sunday and Monday as a series of Pacific
low pressure troughs move east bringing Pacific moisture and
enhanced lift to the area. Snowfall amounts of 3 to 6 inches each
12 hours is expected mainly above 8500 feet with 1 to 2 inches in
the valleys. Strong winds will cause blowing and drifting snow on
Sunday with gusts of 50 to 60 mph on the higher ridge tops. Winds
will also increase over and near the east slopes of the mountains
and through the wind corridor across Sweetwater, southern Fremont
and southern Natrona counties will approach high winds Sunday and
Sunday evening.  Snowfall will mainly remain over the west and
mountains  with little making it east of the mountains.
Temperatures will gradually warm as the winds increase.

.LONG TERM...(Tuesday night through Saturday)
Issued at 239 PM MST Sat Feb 24 2018

An upper level low and associated upper trough is progged by the
models to open up by Tuesday. The upper low is further expected to
shift east-northeast into southeast Colorado by Wednesday. A series
of weak weather systems will move east-southeast through the western
mountain areas in the forecast area between late Tuesday and
Thursday with low chances for mainly light snow expected mainly west
of the Divide. The rest of the forecast area should be generally dry
with a southwest low level flow setting up.

The extended models continue to develop a large upper trough over
the Pacific Northwest Thursday through Friday and then move this
trough closer to our area by Saturday. With the low level southwest
flow expected ahead of the system, there should be periods of snow
expected for the western mountains that should slowly increase in
size through the end of the extended forecast period. Areas east of
the Divide should expect generally mostly dry and warmer temps with
breezy conditions expected especially across the wind corridor from
the Cody foothills to Natrona county. Will continue with previous
thinking that there should be a low chance snow pop east of the
Divide by Saturday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1057 PM MST Sat Feb 24 2018

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

Snow showers will be on the decrease overall through 12z as an
upper level low pressure system dives SE into the Four Corners
area. Snow showers will mainly be confined to the mountains above
8500 feet from 12z-21z Sunday. The next Pacific system will bring
increasing snowfall to the western mountains and far west (KJAC-
KAFO) 21z Sunday-03z Monday with mountains becoming mostly
obscured and prevailing IFR conditions expected at KJAC Sunday
night. KPNA can expect MVFR conditions in light snow late Sunday
evening. Additionally, southwest winds at mountain top level will
increase substantially Sunday night with areas of LLWS possible.

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

VFR conditions will prevail at all terminals through 12z Monday.
Southwest surface winds will increase Sunday afternoon and evening
along the east slopes of the Divide and in the wind corridor from
KRKS-KCPR. Some gusts over 50 knots are possible vicinity KCPR
00z-12z Monday, while areas of LLWS will develop Sunday night
vicinity KCOD-KDUB-KLND. These strengthening winds may also result
in patchy blowing snow and partial terrain obscurations.

&&

.FIRE WEATHER...
Issued AT 239 PM MST Sat Feb 24 2018

Periods of light snow, occasionally moderate will occur across
western Wyoming through Sunday and Monday as a series of Pacific
low pressure troughs move east bringing Pacific moisture and
enhanced lift to the area. Snowfall amounts of 3 to 6 inches each
12 hours is expected mainly above 8500 feet with 1 to 2 inches in
the valleys. Strong winds will cause blowing and drifting snow on
Sunday with gusts of 50 to 60 mph on the higher ridge tops. Winds
will also increase over and near the east slopes of the mountains
and through the wind corridor across Sweetwater, southern Fremont
and southern Natrona counties will approach high winds Sunday and
Sunday evening.  Snowfall will mainly remain over the west and
mountains  with little making it east of the mountains.
Temperatures will gradually warm as the winds increase.
The windy areas will have good to excellent smoke dispersal while the
colder valleys and basins will remain poor.

&&

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

$$

SHORT TERM...Baker
LONG TERM...Troutman
AVIATION...Meunier
FIRE WEATHER...Baker


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