Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 120852
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
152 AM MST Fri Jan 12 2018

.SHORT TERM...Today through Sunday night
Issued at 143 AM MST Fri Jan 12 2018

The Pacific system is currently pushing through WY with a few waves
in ID still evident on radar and satellite. Expect snow to continue
west of the divide through the afternoon today. Precip should be
lighter than it was overnight with periods moderate snowfall. Winds
will continue to be strong in the western mountains and in the
southern areas from Lincoln County through the Green Mountains until
early evening.

Saturday models indicate a fairly steep ridge amplifying over the
west coast states. This ridging should keep WY mild and dry through
Saturday and into Sunday. Sunday night will see a quick moving
Arctic system slide down the eastern side of the ridge. All models
indicate a good shot of snow and colder temps east of the divide
with this system. The Canadian is a little stronger with the cold
push, affecting all the way to the Salt and Wyoming Ranges. At the
moment moisture looks to be a problem for this system and snow
totals look to be low.

.LONG TERM...Monday through Friday
Issued at 143 AM MST Fri Jan 12 2018

Arctic cold front will be entrenched east of the divide to start
this period with some lingering light snow/flurries through the
morning. The surface high with this continues to show stronger and
stronger in the models with 1053-1056mb range over ern MT/wrn ND
Monday morning. Temps will likely be quite cold across our far nrn
and ern zones Monday with highs only struggling up into the teens.
Blend of 30s was way too warm and dropped those down quite a bit but
not as much as I`d like. An expected clear sky with a light wind
behind this system Tuesday morning should lead to some cold morning
lows. Once again, the blend is likely way too warm and lowered those
quite a bit but they will also likely need to be lowered more with
time. The next system will approach from the west Tuesday night and
swing across WY into Wednesday. This system is still moving into the
mean ridge (albeit a weakening ridge) so system will likely not have
a huge impact but a period of snow in the far west mainly. A
stronger system may be in store at the end of the period as we
transition to a mean broad trough over the west (and really the
whole country) by next weekend. Snow will spread into the west later
Thursday or Thursday night through Friday and possibly spill east of
the divide Friday into Friday night. Right now the model guidance is
generally showing a splitting system with the majority of the energy
diving towards the 4-corners. Should see some fairly strong wind
ahead of this system Thursday/Thursday night and possibly as the
trough passes through Friday.

&&

.AVIATION...For the 12Z TAFS through 12Z Saturday morning
Issued at 143 AM MST Fri Jan 12 2018

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

Northwest WY will see VFR conditions through 16Z with local MVFR
ceilings. After 16Z, snow will be developing in NW WY and snow will
continue through tonight. KJAC airport will see MVFR conditions
around 19Z with snow developing around 21Z. IFR conditions will
likely develop at KJAC airport around 00Z and continue through 12Z
Friday. The mountains will be frequently obscured this afternoon and
tonight.

VFR conditions will occur in southwest WY through 03Z. Then KPNA and
KBPI will see MVFR conditions develop after 03Z along with light
snow developing after 06Z Friday.

Please see individual terminal sites for more details.

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

Fog may occur at the KWRL and KLND airports until 16Z with local
MVFR/IFR conditions. Otherwise, VFR conditions will prevail through
tonight. Gusty wind conditions will return to KCPR today and
increase in speed tonight.

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

&&

.FIRE WEATHER...
Issued AT 143 AM MST Fri Jan 12 2018

The winter weather system continues in western Wyoming today.
Lingering areas of light snow through this afternoon and evening.
Winds will be gusty across the western mountains and in the south
from Lincoln County to the Green Mountains. Winds will slow in the
evening Smoke dispersion will be fair to very good today west of
the Divide...poor to fair east of the Divide.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 5 PM MST this afternoon for WYZ001-
002-014-015-024-025.

Winter Storm Warning until 5 PM MST this afternoon for WYZ012-
013-023.

&&

$$

SHORT TERM...Hulme
LONG TERM...Skrbac
AVIATION...Ross
FIRE WEATHER...Hulme



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