685 
FXUS65 KRIW 280711
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
111 AM MDT Tue Aug 28 2018

.SHORT TERM...Today through Thursday night

Rain showers from southern portions of the Bighorn Basin to Natrona 
County will be ongoing this morning, with these showers gradually 
ending from northwest to southeast through the rest of the morning. 
Elsewhere, areas of frost, freezing temperatures and patchy fog are 
expected over the western valleys, including Pinedale and Bondurant, 
as skies clear this morning. Otherwise, a brisk day for late August 
across the Cowboy State with temperatures generally in the 60s. 
Unfortunately, elevated fire conditions will return across portions 
of southern Lincoln and western Sweetwater counties this afternoon. 
This trend will spread across much of the forecast area Wednesday, 
as temperatures warm back into the 70s and lower 80s. Red Flag 
conditions look to be in place over southern and eastern zones, west 
to southwest winds with gusts over 25 mph will occur over these 
areas. Thus, will issue a Fire Weather Watch for the southern 
zones. Conditions are expected to remain dry through the forecast
period, with isolated showers/thunderstorms possible over eastern
portions late Thursday afternoon/early evening.

.LONG TERM...Friday through Tuesday

Some energy over Siberia works across AK on Wed and continues to 
dive se towards another trough that moves out of AK and into MT/srn 
Canada on Thursday. This energy/pocket of cold air holds the trough 
back in the area (well to the north though) through Fri. A cold 
front arrives in the north Thu ngt and then likely dives south into 
our central zones during the day Fri. Some moisture and weak 
instability remains mainly across the north half Friday and in 
srn/sern Sweetwater County aiding in some showers/storms. The tail 
end of an associated jet across ND back into far nrn WY may also 
provide some right entrance region support up north while a jet 
across the far south could provide some left exit region in ern 
Sweetwater Friday. The tail end of this trough may linger a few 
showers into the early morning hours Saturday in our far nern/ern 
zones. Saturday looks dry and mild with highs in the 70s and lower 
80s across the lower elevations with mainly 60s in the high country. 
On Sunday, the GFS is still trying to bring some energy in from the 
west resulting in some tstm potential but the evolution of this 
(some energy from a system over the ern Pacific) is shaky at best. 
Not that it couldn't happen but it's the only one that shows that 
much potential. A general mean trough over wrn Canada down into the 
Pacnw with a generally wly flow underneath is somewhat conducive to 
energy coming in from the west though so we'll have to see. The 
system for Labor Day into at least part of Tuesday originates from 
Kamchatka where an upper low currently sits. The remnants of this 
system swings across MT and srn Canada with most of the energy 
currently forecast to stay to the north. The GFS 5-wave has backed 
off on the srn extent of the developing mean trough and now it 
further to the north along the Canadian border and nwd. With this 
trend, it does not appear right now that a significant Labor Day 
system is in the offing. We will likely see a cold front move swd 
around Monday night aiding in some cooling east of the divide for 
Tuesday. Models are generally dry but they are showing some mid 
level moisture being drawn ne across the area so with time they may 
show a few more showers but forecast is fairly dry for now.

&&

.AVIATION...For the 12Z TAFS through 12Z Wednesday 

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

MVFR ceilings with mountain obscurations are expected over parts of 
the area through mid-morning. The best chance of MVFR ceilings will 
be across the Cody and Lander Foothills, and across Natrona County. 
Ongoing valley rain/mountain snow over the north is expected to 
decrease in coverage from west to east between 10Z and 15Z. By 18Z, 
VFR conditions are expected with skies becoming mainly SKC by 
midday into the early afternoon. 

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

Valley rain/mountain snow over northwest Wyoming should end by 
around 09Z. The associated low ceilings should begin to lift/scatter 
out as well during the predawn hours. Once skies begin to clear, 
some fog/low ceilings could quickly form across the western valleys. 
The fog/low clouds should dissipate/lift by around 15 or 16Z. After 
18Z, expect mainly SKC with mainly light winds.

&&

.FIRE WEATHER...

Apart from ongoing rain showers from the Bighorn Basin to Natrona 
County this morning, conditions will be dry today. These showers are 
expected to end by noon today. Areas of frost, freezing temperatures 
and patchy fog are expected over the western valleys, including 
Pinedale and Bondurant, as skies clear this morning. Temperatures 
will be 5 to 10 degrees warmer west of the Divide and 5 to 10 
degrees cooler east of the Divide. A Fire Weather Watch will be in
effect for Wednesday afternoon and evening across southern zones.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Wednesday afternoon through Wednesday 
evening for WYZ277>279-289.

Winter Weather Advisory until 6 AM MDT early this morning for 
WYZ001-002-008-009-012-014-015.

&&

$$

SHORT TERM...LaVoie
LONG TERM...Skrbac
AVIATION...Murrell
FIRE WEATHER...LaVoie