Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 250831

Area Forecast Discussion
National Weather Service Riverton WY
231 AM MDT Mon Sep 25 2017

.SHORT TERM...Today through Wednesday night
Issued at 220 AM MDT Mon Sep 25 2017

The upper low, currently over west-central WY, will its trek toward
the NE and be over SE MT by 00Z Tuesday. Weak isolated showers
continue over the area, with light precipitation amounts possible
through the rest of the day. The Bighorns will have the best shot
for heavier (0.10") precipitation, as the SE flow around the low
move over the mountains during the day today. Otherwise,
precipitation will end over western and southern portions later this
morning. This trend will continue behind the low, with only very
isolated showers possible over the mountains tonight.

Dry and unseasonably cool temperatures will be in place Tuesday and
Wednesday. Skies will begin to clear today, becoming partly cloudy
by tonight. Areas of fog will be possible Tuesday morning in the
valleys and basins. Mostly cloudy skies will be possible over
northern portions Tuesday afternoon, as the flow aloft becomes
northwesterly. Partly cloudy skies will return across the area on
Wednesday. A weak cold front will pass through northern and central
portions during the day Wednesday, as another area of low pressure
develops over the Desert Southwest. This system will begin to make
its way northward Wednesday and is expected to impact southern
portions of WY later in the week.

.LONG TERM...(Thursday through Monday)
Issued at 220 AM MDT Mon Sep 25 2017

The models are bringing a weather system into the Colorado/Utah
area Thursday and then into southern WY by Friday morning. It
weakens over WY Friday into Fri night. Isolated showers and storms
will occur Thursday in the southern zones. Friday will see
isolated activity across the south and east. The models have made
a change to unsettled weather Saturday into Sunday. Some showers
and isolated storms develop in the west Saturday afternoon and
then spread across the rest of the area Saturday night into Sunday
morning. Breezy areas Saturday into Saturday night with this
system. Lingering showers Sunday morning east of the continental
divide with drying during Sunday afternoon. Next Monday looks dry
at this time. High temperatures will be seasonal Thursday through
Saturday, then a little cooler Sunday, warming back up next


.AVIATION...For the 12Z TAFS through 12Z Tuesday
Issued at 220 AM MDT Mon Sep 25 2017

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

An upper low pressure area will continue to circulate across southern
Wyoming through Monday morning with an extensive deck of low clouds
expected to continue across the area. There will also continue to be
areas of MVFR/IFR and mountain obscurations west of the Divide
with the low clouds and mainly light snowfall expected until
around 12Z Monday at most TAF sites.

It is expected that the lowest clouds/visibilities should remain in close
vicinity of the upper low across southwest-south portions of Wyoming
in the near term portion of the forecast. The low clouds/lingering light
precip should lift out of the region by Monday afternoon after 18Z, with
MVFR to VFR conditions expected generally after the 18Z time frame.

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

The persistent deck of low clouds in vicinity of the upper low rotating
across Southern Wyoming will continue until around 18Z Monday. Will
continue with mention of some light snow/mixed precipitation in the first
few hours of the forecast, with the precip expected to be generally east
of the TAF sites after 18Z Monday. After the lower ceilings lift after 18z
Monday, ceilings should gradually improve to above MVFR to VFR by around
00Z Tuesday at most locations.


Issued AT 220 AM MDT Mon Sep 25 2017

Isolated showers with light precipitation expected across the area
today. This activity will end over western and southern portions
this morning, as the storm system makes its way toward SE MT through
the day today. Precipitation amounts are expected to remain low,
except in the Bighorns, where heavier (0.10") precipitation could be
possible. Otherwise, light winds are expected today and through the
middle of the week , but gusts up to 15 mph will be possible this
afternoon across southern portions. Clearing conditions will also
begin today, with partly cloudy skies returning by Tuesday. Areas of
fog will also be possible in the valleys and basins Tuesday morning.
Dry and unseasonably cool conditions will be in place through





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