Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 142031
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
131 PM MST Sun Jan 14 2018

.SHORT TERM...(This evening through Wednesday)
Issued at 114 PM MST Sun Jan 14 2018

A Canadian cold front moving south from Montana will move south
across the Big Horn basin, Johnson, Natrona and Fremont counties
and surrounding mountains tonight with light snow becoming more
widespread through the evening. Snowfall is expected to range
from 1 to 3 inches with up to 5 inches in the mountain areas.
Colder temperatures will move in behind the cold front as well.
Slick, snow packed and icy roads can be expected through Monday
morning.  Snowfall will taper off through morning ending by noon.
In the west colder and rather dry north northwest flow will remain
tonight and Monday. Fog in the valleys likely to continue with
inversions in place and limited mixing. Expect it to remain dry
through Tuesday with an increasing chance of snow showers coming
in from the west southwest Tuesday night and Wednesday.

.LONG TERM...(Wednesday night through Sunday)
Issued at 114 PM MST Sun Jan 14 2018

Conditions will be dry at the beginning of the forecast period, as a
transitory ridge moves over the region by 12Z Thursday. Timing of
precipitation reaching the far west continues to be pushed back, as
the longwave trough digs as it makes its way onshore over the PACNW.
SW flow aloft will usher in this next round of precipitation, with
chances increasing across NW portions and the western mountains
through the day Thursday.  A cold front associated with this system
will quickly pass through the forecast area through the day Friday.
As it does so, strong winds may be possible in wind prone locations,
like the Wind Corridor. Scattered PoPs from morning snow/afternoon
rain/snow and rain will occur east of the Divide along and behind
the front. This will be brief ahead of the front, as temperatures
drop below freezing behind the front and continue as snow Friday
night. With the jet bringing in plenty of Pacific moisture and
associated dynamics, western portions could receive a healthy dose
of fresh snow Thursday night through Friday. Snow will gradually end
Friday night into Saturday, from northwest to southeast, as another
transitory ridge and a somewhat zonal flow pattern take shape
Saturday and Sunday. Apart from warming that could occur Thursday,
temperatures will be near to slightly below normal through the rest
of the period.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday)
Issued at 114 PM MST Sun Jan 14 2018

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

Higher mountains will remain mostly obscured through for a couple
more hours, before clearing this evening. Areas of IFR/MVFR ceilings
will likely seep in from eastern Idaho to vicinity KJAC- KBPI
overnight tonight. These conditions are expected to continue through
the rest of the TAF period at KJAC. LLWS will be marginal tonight
vicinity KPNA. Otherwise, mid to high level clouds will reenter
after 18Z Sunday.

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

-SN is ending vicinity and north of a KPOY-KBYG line, however the
Bighorn Range and northern Absaroka Range remain mostly obscured.
VFR conditions are expected to prevail through the period. LLWS will
develop this evening at KWRL and subside at KRIW. Mid to high level
clouds will reenter the area in the NW flow between 15Z-18Z Sunday,
from KCOD to KCPR. These clouds will progress southward through the
afternoon Sunday. Marginal MVFR clouds will begin to impact the
Bighorn Range by 21Z Sunday, as a cold front begins moving
southward. These clouds will extend from a KPOY-KDGW line by 00Z
Monday.

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

&&

.FIRE WEATHER...
Issued AT 114 PM MST Sun Jan 14 2018

A Canadian cold front moving south from Montana will move south
across the Big Horn basin, Johnson, Natrona and Fremont counties
and surrounding mountains tonight with light snow becoming more
widespread through the evening. Snowfall is expected to range
from 1 to 3 inches with up to 5 inches in the mountain areas.
Colder temperatures will move in behind the cold front as well.
Slick, snow packed and icy roads can be expected through Monday
morning.  Snowfall will taper off through morning ending by noon.
In the west colder and rather dry north northwest flow will remain
tonight and Monday. Fog in the valleys likely to continue with
inversions in place and limited mixing. Expect it to remain dry
through Tuesday with an increasing chance of snow showers coming
in from the west southwest Tuesday night and Wednesday.

&&

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

$$

SHORT TERM...Baker
LONG TERM...LaVoie
AVIATION...LaVoie
FIRE WEATHER...Baker



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