Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 050535 AAA
AFDCYS

Area Forecast Discussion...UPDATED
National Weather Service Cheyenne WY
1035 PM MST Sun Dec 4 2016

.SHORT TERM...(This evening through Tuesday night)
Issued at 310 PM MST Sun Dec 4 2016

Current wind headlines look good across the wind prone areas
tonight as gusts have routinely been between 45 to 55 mph with
occasional gusts up to 62 mph today. Believe these winds will
increase further as the strong cold front approaches the area this
evening. Would not be surprised to see a few gusts around 70 mph
near Arlington and possibly near the I80 summit. Across the lower
elevations...winds will be downslope with overnight lows not as
cold as the last several nights...with lows in the mid 20`s to mid
30`s expected.

Forecast is on track for Monday with a few differences with winter
headlines. Models continue to show the initial cold front
beginning to move through the forecast area early Monday morning.
For most of southeast Wyoming...high temperatures may actually
occur in the morning with temperatures dropping into the teens and
even single digits by the afternoon. Wind chill values may even
drop between zero to 15 below zero west of I-25 by Monday evening.
There is still some concern of strong winds spreading into the
high valleys and high plains along I-25 late in the morning.
However...GFS remains the only model showing strong subsidence
and potential gusts around 60 mph as the front moves through.
Decided against expanding the High Wind Warning for now...but
will look at it again tonight and early tomorrow morning. As for
snow...snow accumulation should be limited across the area with
little or no snowfall across western Nebraska through Monday
evening. Dry downslope winds will prevent steady snowfall over a
prolonged period of time...outside of the mountains at least.
Decided to issue a Winter Weather Advisory for the mountains
beginning late tonight for 4 to 8 inches of snow and blowing snow.
Snowfall will be short in duration with a 12 hour lull between the
next onset of snowfall on Tuesday. Decided to issue a Winter
Weather Advisory for the Arlington area for 1 to 3 inches of snow
and some blowing snow. Brief blizzard-like conditions are possible
in this area...but noticed the strongest winds lower pretty quick
behind the front...and there should not be much snow on the ground.
Otherwise...had to increase snow accumulations for Converse county
as most models show a decent chance at 2 to 4 inches of
accumulation around and north of Douglas. May need a last minute
Advisory for that area depending on the timing. Wind Advisories
may be needed for the southern Nebraska Panhandle Monday afternoon
with the potential for 30 to 35 mph winds and gusts around 45 mph
as the front moves through the area.

For Tuesday...models are now in better agreement with the arctic
front and associated snowfall. All models now show an upper level
shortwave digging southeast into the eastern Great Basin region on
Tuesday with ample jet energy/dynamics aloft as well as some warm
air advection to off the surface. Meanwhile...the arctic front
will move southward across the plains and should enter the
forecast area by Tuesday evening. With warm air overrunning cold
air near the surface...upslope and dynamic lift...confidence is
increasing with a moderate snowfall event beginning early
Tuesday...mainly southward along I-80. Areas along and east of the
southern and central Laramie Range may see 3 to 6 inches of snow
with locally higher amounts on the I80 summit and in the
mountains. Daytime highs in the teens to middle 20s on Tuesday
will seem warm in comparison to Tuesday night and Wednesday.
Thankfully...winds are not much of a concern with this part of the
storm as winds shift into the east/northeast between 10 to 20 mph
across the plains.

.LONG TERM...(Wednesday through Sunday)
Issued at 245 PM MST Sun Dec 4 2016

Lingering light snow/flurries will end over the CWA Weds morning
with departure of an upper shortwave to the east. It will be very
cold however Weds as an arctic surface high settles down the high
plains with max temps only in the single digits to lower teens
expected. Clearing skies and relatively light winds Wednesday
night/Thursday morning should allow temps to fall below zero over
much of the CWA. A little warmer but still cold Thursday as the
cold airmass begins to pull out of the area and downslope flow
sets up. Much warmer Friday as a rather flat upper ridge moves by
and lee troughing deepens over the high plains. saturday and
Sunday looking seasonably cool under a generally westerly flow
aloft. Should see some snow showers at times mainly over the mtns
as weak impulses move across the region in this flow.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1026 PM MST Sun Dec 4 2016

Snow will spread east into Carbon County overnight, with MVFR
cigs/vis at RWL and SAA airfields by 12Z. The mountains will be
obscured by snow and low cigs. Snow showers may impact LAR after
15Z, and AIA and CDR after 17Z. VFR cigs will prevail elsewhere.
Strong and gusty pre-frontal winds will continue through Monday
morning across southeast WY, then shift into the west and northwest
and remain rather gusty areawide through the afternoon.

&&

.FIRE WEATHER...
Issued at 236 PM MST Sun Dec 4 2016

No Fire Weather concerns through the week as a very cold arctic
airmass settles over the area. Strong winds will continue across
southeast Wyoming through Monday resulting in cold wind chill
readings. Widespread accumulating snowfall is expected Tuesday and
early Wednesday.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Weather Advisory from 3 AM to 8 PM MST Monday for WYZ112-
     114.

     High Wind Warning until 8 AM MST Monday for WYZ106-110-116-117.

     Winter Weather Advisory from 8 AM to 8 PM MST Monday for WYZ110.

NE...None.
&&

$$

SHORT TERM...TJT
LONG TERM...RE
AVIATION...MAJ
FIRE WEATHER...TJT


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