Area Forecast Discussion
Issued by NWS Riverton, WY

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272
FXUS65 KRIW 060047
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
547 PM MST Mon Dec 5 2016

.UPDATE...

Quick update to allow the winter weather advisory expire at 6 pm.
Only some lingering snow band showery activity impacting eastern
Fremont/Natrona Counties, but even these look to be shrinking in
size.

&&

.PREV DISCUSSION... /issued 202 PM MST Mon Dec 5 2016/

Short Term...Tonight Through Tuesday

Snow should taper off and shift east of the area this evening
with clearing. temperatures will be cold with most areas falling
below zero and some western valleys could see -20. Some low
stratus and patchy fog may develop but the east and south will
remain breezy. Thursday will be dry and cold. Some wind in the
south and east may mix the air mass there enough for some warming
but the valleys and basins should be well trapped with temperature
inversions.

Long Term...Tuesday Night Through Monday

A weak low pressure trough will move into the northwest from the
Idaho Panhandle and western Montana bringing areas of light snow
to the western and northern mountains Tuesday night and
Wednesday. Snowfall amounts should be light. As this trough moves
southeast across the west...into northwest Colorado some light
snow may spread along and east of the Continental divide and
across the southwest. Most areas will remain cold with lows below
zero and highs in the single digits to teens. The cloud cover and
light snow may hold up temperatures. The threat of light snow will
continue in southern and central areas on Wednesday with clearing
across the north and west. High pressure with cold temperatures
will be in place Wednesday night into Thursday. In the west the
leading edge of Pacific moisture should move into the mountains in
the afternoon. There is potential for another strong Pacific jet
to set up bringing a deep moist plume of pacific moisture into the
west through Saturday night with potential very significant
snowfall in the western mountains and valleys and another strong
wind event east of the Continental divide. Temperatures will warm
from thursday through Saturday. Saturday night and Sunday a cold
front should move south east of the Continental divide spreading
snow to the area and bring another shot of cold air into the
region.

Aviation.../00Z Issuance/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

Marginal MVFR-VFR conditions across all locations except KCPR.
Expect temporary IFR conditions to continue through 06z Tuesday, as
snow bands continue moving SE in a narrow area off the Bridger
Mountains. Mountain obscurations will continue through the period.
Gusty northwest winds will quickly subside this evening, except
vcnty KDUB-KRIW. Clear skies or possibly some thin, mainly
translucent lower clouds LCL MVFR ceilings, will prevail 06z-12z
Tuesday along with light and variable wind.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

Some clouds will linger this evening, partially obscuring mountains
above 8500 feet. Surface high pressure will build into western
Wyoming this evening with winds diminishing and mostly clear skies.

Fire Weather...

Snow should taper off and shift east of the area this evening
with clearing. temperatures will be cold with most areas falling
below zero and some western valleys could see -20. Some low
stratus and patchy fog may develop but the east and south will
remain breezy. Thursday will be dry and cold. Some wind in the
south and east may mix the air mass there enough for some warming
but the valleys and basins should be well trapped with temperature
inversions. Most areas will have a very stable air mass with
temperature inversions with overall poor smoke dispersal through
Wednesday.

&&

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

&&

$$

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



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