Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 232132
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
232 PM MST Mon Jan 23 2017

.SHORT TERM...Tonight through Thursday

Snow has been falling in the west...southwest and south today and
some snow is now developing in the central zones as of 21Z.
Cooling cloud tops are occurring in the region ahead of this
weather system that is forecast to move through the Rocky
Mountain region tonight and exit Tuesday afternoon. Snowfall out
west and southwest has been decent so far. The snow will continue
in the west and southwest through Tuesday morning. In the central
zones, snow will continue to increase in coverage the rest of the
daylight hours with decent snow amounts expected through Tuesday
morning. Expecting the best snowfall rates later this evening
through sunrise Tuesday. In the north, the snow will develop this
evening and continue through Tuesday morning. Current warnings and
advisories will not be altered for now. Will have to monitor the
central zones later tonight to see if an upgrade might be needed.
Worded the statement with locally higher amounts. The snow will be
decreasing over the region Tuesday afternoon from north to south.
Lingering light snow in the mountains Tuesday night into Wednesday
morning. Then scattered light snow for the Western mountains
Wednesday afternoon and night and even into Thursday as this upper
level trough hangs around through Thursday. Mainly dry for the
rest of the region Wednesday through Thursday. Temperatures will
be on the cold side Tuesday through Thursday as 700 MB temps do
not vary much during this timeframe. Lows will be tricky due to
cloud cover Tues night, but with a clearing sky Wednesday night,
it will get very cold in the valleys and basins.

.LONG TERM...Thursday night through Monday

Beginning of FCST, boundary layer warming with residual moisture
under exiting cold air aloft will allow from a short period of snow
showers to continue but wind down west of the Divide Thursday night
perhaps into a few hrs of Friday morning before mid/upr ridging
slowly begins to make inroads across the FA with the ridge axis
orientation from cntrl California to the nrn high plains by Saturday
night. This will mostly keep a clipper front out of the ern FA over
the same time frame. Above and to the northwest of this ridge out
over the EPAC Saturday night, a modest shortwave trof is fcst to
exist. This SW trof will top the rather strong ridge and arrive
near/over nrn/nwrn WY Sunday evening...moving into the Plains by
Monday morning. This will also generate a front that will push
through the region east of the Divide Monday morning. With the storm
track taking a northerly route around the ridge, the FA will be cut
off from significant moisture with little in the way of
precipitation falling through the end of the forecast period. ATTM,
it appears that the wrn CONUS will have to wait until mid to end of
next week before the Pacific opens back up.

&&

.AVIATION.../00Z ISSUANCE/

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

A strong upper level disturbance will continue to rotate across the
forecast area tonight through Tuesday as a cold front also pushes
into/through northern Wyoming. This will also continue relatively
widespread shsn across the region west of the Divide, particularly
near and south of a KJAC to KPNA to KRWL line into Tuesday morning
before tapering off. Conditions will range at times from VFR all the
way down to LIFR in low CIGs and VIS in snow. Please see individual
TAFs for timing and intensity of this significant weather system.

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

A strong upper level disturbance will continue to rotate across the
forecast area tonight through Tuesday as a cold front pushes
into/through northern/central Wyoming this afternoon...and down to
southern WY overnight tonight. This will bring widespread -shsn to
near all of the forecast area by Tuesday morning...with heaviest
snowfall found from later this evening through Tuesday morning near
and south of a KDUB to KRIW to KGCC line. Conditions will range at
times from VFR all the way down to LIFR in low CIGs and VIS in snow.
Please see individual TAFs for timing and intensity of this
significant weather system.

&&

.FIRE WEATHER...

Periods of snow through Tuesday afternoon in most places. The
heaviest snow will fall through Tuesday morning with lighter snow
occurring through Tuesday afternoon. Scattered mountain snow
showers Wednesday and dry Thursday. Mixing heights will remain
fairly low through Thursday with poor to fair smoke dispersal.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...

Winter Weather Advisory until 5 PM MST Tuesday for WYZ014-015-
026-028>030.

Winter Weather Advisory from 5 PM this afternoon to 5 PM MST
Tuesday for WYZ018>020-022.

Winter Storm Warning until noon MST Tuesday for WYZ012-013.

Winter Weather Advisory from 5 PM this afternoon to noon MST
Tuesday for WYZ005-007-017.

Winter Storm Warning until 5 PM MST Tuesday for WYZ023>025-027.

Winter Weather Advisory until noon MST Tuesday for WYZ002.

&&

$$

SHORT TERM...AR
LONG TERM...Braun
AVIATION...Braun
FIRE WEATHER...AR


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