Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 281035
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
335 AM MST Tue Feb 28 2017

.SHORT TERM...Tuesday through Thursday night

Currently we have one area of snow across the Big Horn Mountains as
a shortwaves moves across the area. Meanwhile, across the west
things are quiet at this point. Another wave will move into the west
tomorrow but this one looks to have less moisture and less upper
level forcing than the wave that moved through on Monday. As a
result, we will not issue any advisories at this time. There is the
possibility for a heavier band of snow somewhere, but that is
impossible to pinpoint at this time. Meanwhile, dry conditions
should be the rule across most areas East of the Divide. There is a
small chance some snow may leak into Big Horn Basin but amounts
should be light. Otherwise expect another day of below normal
temperatures. A gusty wind will continue across the usual spots,
a.k.a. the lee of the Absarokas and the southwestern Wind Corridor.
The steadiest snow should end in the evening with only leftover
showers late at night.

On Wednesday another wave will move into the west but this wave
looks even weaker than the one on Tuesday so only lighter snow is
expected. The risk of high wind will increase Wednesday across the
Lee of the Absarokas as the 700 millibar winds increase. A high wind
watch may be needed for the Cody foothills. Mainly dry conditions
should persist East of the Divide once again. A bit of snow may be
possible across northern Wyoming at night as an Alberta Clipper
drops southward into the area. There could be some gusty winds
across Johnson County as well with cold advection behind the cold
front.

A general drying trend will continue for most areas on Thursday. At
this point, only light snow is expected across the western
mountains. There could also be a few showers in the Big Horn
Mountains with the northwest flow. Otherwise, mainly tranquil
conditions are expected other than some gusty winds in the usual
locations.

.LONG TERM...Friday through Tuesday

The models have gone drier for Friday in the northwest part of WY
with only minor coverage of snow in the mountains. The rest of the
region will be dry with breezy areas. Moisture increases in the
west late Friday night into Saturday with a good chance of snow in
the mountains and the far west valleys. Snow looks to decrease
Saturday night in the west. East of the divide will be dry
Saturday and Saturday night. The models are indicating an active
weather system for Sunday and Sunday night. The bulk of the energy
will pass across Montana and northern WY. The best chance of
precipitation will be in the west and north with lesser activity
in the central and south. It looks to be windy Sunday into Sunday
night in many locations. Cold front passes late Sunday night. Next
Monday looks dry for most places. There may be lingering snow
showers in the northwest mountains Monday. GFS model brings
moisture into the west next Tuesday while the ECMWF model is dry.
Went with collaboration forecast and left a chance of precip in
the west. Dry weather in the east next Tue. Temps will be milder
Friday through Sunday, then cooler Monday, warming back up next
Tuesday. Lower elevation snowmelt east of the divide will occur
over the weekend which would lead to runoff and localized
flooding.

&&

.AVIATION.../12Z ISSUANCE/

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

Widespread MVFR to IFR conditions in low ceilings and snow are
expected to develop over the far west including KJAC and KPNA
terminals between 15Z and 19Z. Farther southeast, the coverage and
confidence in MVFR/IFR is not enough to include at KRKS or KBPI
terminals. The peak in snowfall is expected between 18Z Tuesday and
00Z Wednesday, with snowfall gradually ending in most of the lower
elevations during the evening hours. However mountain snow will
likely continue through Tuesday night. Breezy to windy westerly
winds will develop in most areas by midday in most locations. Winds
will be more southerly in Jackson hole. The windy conditions will
also cause areas of blowing snow. Mountains will be obscured much of
times.

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

An area of snow showers across the Bighorn Mountains and Johnson
County will exit the area by 12z. MVFR and brief IFR conditions
could occur with these snow showers. Otherwise, VFR conditions are
expected with variable mid-high cloudiness. Windy west to southwest
wind are expected to remain or develop in most areas today. The
windiest areas will be between South Pass and Casper where some
blowing snow will occur. Some low level wind shear will be possible,
mainly on lee side of mountain ranges especially if winds weaken.

Please see the Aviation Weather Center for the latest information on
icing and turbulence forecasts.

&&

.FIRE WEATHER...

Fire Danger low for all of Wyoming today as a decent snow cover and
below normal temperatures will continue for many areas. Smoke
dispersion will be fair to very good across most of the forecast
area this afternoon. Periods of light snow will continue across the
western mountains. A gusty wind will continue from the Red Desert
through Natrona County today as well as the Lee of the Absarokas.
Strong to possibly high winds will be possible in the Cody Foothills
on Wednesday.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...None.

&&

$$

SHORT TERM...Hattings
LONG TERM...AR
AVIATION...WM
FIRE WEATHER...Hattings


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