Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 051942
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1242 PM MST Tue Dec 5 2017

.SHORT TERM...(This evening through Friday)
Issued at 1230 PM MST Tue Dec 5 2017

A very large high pressure ridge along the west coast extending
north well above the Arctic Circle will produce cool dry northerly
flow over western and central Wyoming through the week with gradual
warming.  Some moisture over northern and eastern Wyoming will
support some light snow showers at times over the northern Bighorn
and Absaroka mountains.  Cold air advection will battle areas of down
slope winds producing lee side warming making the temperature forecast
the forecast challenge through Friday.

.LONG TERM...(Friday night through Tuesday)
Issued at 1230 PM MST Tue Dec 5 2017

The extended will feature warming temps at the higher elevations and
mixed areas along with colder air remaining in the basins and
valleys underneath temperature inversions, given the long nights and
short days for this time of year as high pressure amplifies to our
west and attempts to build in from the west. Models struggle with
this pattern, warming up the basins and valleys too quickly. As we
remain on the front side of the ridge at the beginning of next week,
another backdoor cold front will push south across the area next
Monday, enabling the cold inversions to mix out before cooling off
again along with cooling temps elsewhere. This next front will come
through dry early next week with any moisture sliding off to the
northeast of our area.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday)
Issued at 1230 PM MST Tue Dec 5 2017

A stratocumulus deck will continue to obscure the far western
mountains through the rest of this afternoon with the higher peaks
poking through the deck. The cloud deck will hover around 2000 feet
agl. These clouds will dissipate by sunset this evening. Otherwise,
VFR conditions with variable mid-high level cloudiness are expected.
Breezy west to northwest wind will occur at most locations with
winds becoming more northerly east of the Divide late in the
afternoon into the early evening as a weak frontal boundary pushes
south across the area. Winds will continue through Wednesday, but
from primarily a northwest direction east and west of the divide
along with VFR conditions.

&&

.FIRE WEATHER...
Issued AT 1230 PM MST Tue Dec 5 2017

A very large high pressure ridge along the west coast extending
north well above the Arctic Circle will produce cool dry northerly
flow over western and central Wyoming through the week with gradual
warming.  Some moisture over northern and eastern Wyoming will
support some light snow showers at times over the northern Bighorn
and Absaroka mountains.  Cold air advection will battle areas of down
slope winds producing lee side warming making the temperature forecast
the forecast challenge through Friday.

&&

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

$$

SHORT TERM...Baker
LONG TERM...Lipson
AVIATION...Lipson
FIRE WEATHER...Baker



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