Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 190840

Area Forecast Discussion
National Weather Service Riverton WY
240 AM MDT WED OCT 19 2016

.SHORT TERM...Today through Friday night

Imagery shows large broad longwave trof across the CONUS. Strong
120+ jet stretches across the nrn half of the CONUS with the jet
dipping over the srn portion of WY. Embedded shortwave trof now
moving into wrn WY...slightly behind schedule. The surface has high
pressure across the wrn much of the wrn CONUS into wrn WY with lower
pressure to the east and a slow moving cold front to the north in
MT. Light snow finally making its way into wcntrl and nwrn WY.

Today and tonight: The main trof axis/embedded shortwave...currently
working its way across wrn WY somewhat behind
increasing moisture, dynamics and snowfall this morning across the
west. Tetons and Gros Ventre mountains may see a few inches of snow
this morning as a sfc front in addition to the best PVA and moisture
feed into the region for a short period of time this morning...but
it will likely be few a far between at this point considering how
the system looks this morning compared to 24 hrs ago. Expecting 1 to
4 inches of new snowfall for most of the mountains west of the
divide this morning. 1 to 5 inches will also be possible over the
Bighorns later in the day. Otherwise, as the cold front moves into
the northern and central FA later this morning, it may produce a
little snowfall across the lower elevations...with some locations in
central and northern WY seeing anywhere from a trace to a half an
inch. 0.5 to perhaps 2 inches will be a possibility in the foothills
of the southern Big Horn Basin and across the foothills of northern
Johnson...including the town of Buffalo.

Tonight through Friday night: With the upper trof finally clearing
WY and precip ending from west to east...modest ridging aloft,
drying and warming will work across the FA. Only real weather of any
significance will be some breezy gusty winds across the wind
corridor on Thursday Friday night...and over the northern Cody
foothills Thursday night and again Friday night with perhaps near
high wind for short periods late Friday/early Saturday.

.LONG TERM...Saturday through Wednesday

Upper level ridging for the weekend with mainly dry and mild to
warm temperatures. Cannot rule out a very isolated shower over Yellowstone

Global models are in good agreement with an upper low/trough
digging from the Gulf of Alaska Saturday to off the West Coast
Sunday. Models generally show the trough axis remaining along or
just off the West Coast early to midweek with generally a
southwest flow over the region. Shortwave troughs, some upper jet
energy and a cold front will result in inclement weather at times,
but models differ significantly on the details and timing this far
out. For now it appears Monday night/Tuesday will have the best
shot of precipitation out west as a Pacific cold front pushes into
the area. Due to differences this far out will broad brush slight
to chance PoPs out west Monday through Wednesday with an emphasis
on Monday night/Tuesday time frame. Although areas east of the
Divide could see some precip at times, decided to keep those
areas dry until there is better model continuity with timing of
the main systems/fronts occur.

Snow levels will be high Monday with valley rain/mountain snow
with snow levels lowering close to valley floors out west Monday
night/Tuesday. Precipitation amounts look to be mainly on the
light side, so not expecting any major storms at the moment.




Areas of MVFR and IFR will occur due to lower ceilings and
visibilities due to snow showers through 15Z. Conditions will
gradually improve after 15Z as the snow showers will be mainly
in the mountains through 23Z. Expect mountains to be frequently
obscured through 23Z. After 00Z, the snow showers end in the
mountains with clouds decreasing. VFR conditions will occur at
the KRKS terminal site through the period.


VFR conditions prevail through 12Z. Then scattered snow showers
will develop after 12Z and continue through 00Z. Areas of MVFR
conditions will occur in snow showers as ceilings and
visibilities will lower. Check the latest terminal forecasts
for more details as conditions will change quickly as these
snow showers pass through the area today. VFR conditions will
prevail after 00Z as the snow showers end by 03Z.



Fire danger low all areas today as minimum RH values remain above to
well above 25 percent and winds remain relatively light. The end of
an upper level disturbance that has brought rain and snow to WY over
the past few days will exit the area tonight after a cold front
moves through the forecast this morning with light snow ending
across the west and a chance for light rain or snowfall moving
across the lower elevations east of the Divide. Then, modest warming
and drying will occur from Thursday onward with no chance for
precipitation through at least Friday night.Winds will get gusty in
the usual areas both Thursday and Friday.


.RIW Watches/Warnings/Advisories...None.



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