Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 150509
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1009 PM MST Sat Jan 14 2017

.UPDATE...

06Z Aviation discussion inserted below.

&&

.PREV DISCUSSION... /issued 128 PM MST Sat Jan 14 2017/

Short Term...Tonight Through Tuesday

Cold dry high pressure will remain over the area through
Monday night. The valleys and basins will remain cold with
strong temperature inversions and light wind. the mountains and
foothills will warm as will the eastern plains in natrona and
southern johnson county where southwest winds will increase. the
south will remain cloudy with patchy fog...while the valleys and
basins will have fewer clouds but will have patchy fog as well.
Monday night and Tuesday clouds will move into the west ahead of a
Pacific low pressure trough which will move towards the Pacific
Northwest coast. The clouds will aid in warming.

Long Term...Tuesday night Through Saturday

Some light snow may develop in the higher mountains of the west
late Tuesday on the eastern edge of the cloud mass associated with
the incoming Pacific trough. A better chance of light mountain
snow across the west will move in Wednesday and Wednesday night.
Snowfall is expected to increase in both coverage and intensity
across the west and southwest Thursday and southwest winds will
become stronger and more widespread over and near the east slopes
of the mountains east of the Continental Divide and through the
wind corridor from Rock Springs to Casper. Strong winds will
likely occur in the cody foothills. As the clouds and wind
increase...temperatures will rise significantly with the Big Horn
and Wind River Basins warming last. Thursday night a weak Canadian
cold front is expected to move into northern Wyoming with areas
of snow developing across the north. Areas of snow will continue
across the mountains and north Friday. The main Pacific low
pressure trough is modeled to dig south into the Great Basin
drawing much of the moisture south of the area Friday night. As
the low develops south towards the four corners area...north
northeast winds will develop across the area with colder air and
areas of low clouds and snow developing Friday night and Saturday.

Aviation.../06Z Issuance/

The Rock Springs /KRKS/ terminal remains in dense fog, and is
expected to remain at or below airfield minimums through at least
noon Sunday. There is a better shot of fog lifting Sunday
afternoon/evening than on Saturday as some mid-high level clouds
from the south will overspread southern Wyoming, a slight westerly
breeze is expected to develop towards evening, and the models are
showing the boundary layer moisture trending drier than yesterday.
Elsewhere, patchy morning fog will be possible in basins and
valleys. Winds will be mainly light through the period.

Fire Weather...

Cold dry high pressure will remain over the area through
Monday night. The valleys and basins will remain cold with
strong temperature inversions and light wind. the mountains and
foothills will warm as will the eastern plains in natrona and
southern johnson county where southwest winds will increase. the
south will remain cloudy with patchy fog...while the valleys and
basins will have fewer clouds but will have patchy fog as well.
Monday night and Tuesday clouds will move into the west ahead of a
Pacific low pressure trough which will move towards the Pacific
Northwest coast. The clouds will aid in warming. With cold air
trapped in the valleys and basins with increasing temperature
inversions...mixing will be limited and wind will be light
combining for poor smoke dispersal expected through Monday.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 9 AM MST Sunday for WYZ028>030.

&&

$$

UPDATE...WM
SHORT TERM...C.Baker
LONG TERM...C.Baker
AVIATION...WM
FIRE WEATHER...C.Baker



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