Area Forecast Discussion
Issued by NWS Cheyenne, WY

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425
FXUS65 KCYS 281825
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1125 AM MST Mon Nov 28 2016

.UPDATE...
Issued at 1117 AM MST Mon Nov 28 2016

Update to cancel the High Wind warning over the South Laramie
Range area and to post a wind advy for the southern Nebraska
Panhandle. Also made minor changes to temps and sky to match
observed conditions.

&&

.SHORT TERM...(Today through Tuesday Night)
Issued at 311 AM MST Mon Nov 28 2016

Upper low is currently spinning over central South Dakota with a
pretty strong pressure gradient across the CWA. Winds have come
down a bit over the past few hours with gusts mostly 35 to 45 mph
in the wind prone areas. The llvl gradient does not change much
through the day. Expect winds to increase after sunrise as better
mixing occurs in the llvls. Went ahead and dropped the High Wind
Warning for the Bordeaux area as winds have been weaker there
compared to the southern Laramie Range, and winds will be more
west-northwest which tends to be less favorable for Bordeaux. The
higher elevations of the southern Laramie Range and adjacent
foothills should see mixing down of winds of 40-50 kts. Other
change to the winter headlines was to drop the Blizzard Warning
over Arlington and go with a Winter Weather Advisory through the
aftn. Snow rates should let up over that area through the morning,
with vis reduction mostly due to blowing snow. With vis over the
past few hours no longer consistently below a quarter mile (more
of a half mile to a mile), feel that a Blizzard Warning is no
longer warranted.

Moist cyclonic flow aloft will continue through Tuesday night with
orographic snows persisting in the Sierra Madre and Snowy Ranges.
The models do show snowfall rates dropping into the aftn. 700 mb
flow also becomes northwesterly tonight into Tuesday. Thus would
expect a little less favorable orographics, especially compared to
what has been occurring over the Sierra Madre Range. A shortwave
will dive southward across the northeastern zones tonight into
Tuesday morning. Although the best dynamics are expected to remain
over central South Dakota, will have to monitor this. Another day
of good mixing and strong flow aloft (700 mb winds of 40-50 kts)
will mean breezy to windy conditions yet again. Future shifts will
likely have to consider a wind advisory over the Panhandle for
Tuesday aftn.

.LONG TERM...(Wednesday through Sunday)
Issued at 311 AM MST Mon Nov 28 2016

A stagnant, but vigorous long-wave trough will finally begin to pull
east on Wednesday. The GFS and ECMWF are in good agreement w/ a mid-
level vort lobe moving across the area, so opted to maintain chances
for mountain snow showers through Wednesday afternoon. Any lingering
wrap-around precipitation over the plains should have ended with the
surface low progged to be over the western Great Lakes. It is likely
to be another blustery day with strong low-level gradients promoting
a ribbon of 40-50 knot flow at H7-H8 along/east of the Laramie Range
through early afternoon. Mountain snow showers should quickly return
on Thursday with the next mid-level disturbance. Medium range models
generally show troughing through early Saturday, so expect unsettled
conditions to persist for the high elevations. A strong cold frontal
passage late in the week will push H7 temperatures between -10 deg C
and -15 deg C areawide by mid-day Friday. Lows may bottom in the mid
single digits west of the Laramie Range on Fri/Sat morning. A slight
moderation in temperatures is expected over the weekend, w/ highs on
the plains possibly returning to the 40s on Sunday. However, it will
remain on the breezy side.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1125 AM MST Mon Nov 28 2016

Northwest winds will remain quite gusty at all terminals through
the period. 25 to 35 kts will be common, with perhaps weaker
winds tonight in the high valleys west of the Laramie Range. Snow
showers with brief MVFR conditions may affect locations across
Carbon County this afternoon. These snow showers should spread
east across the plains tonight through Tuesday morning.

&&

.FIRE WEATHER...
Issued at 311 AM MST Mon Nov 28 2016

No fire weather concerns this week. It will be breezy to windy
through Wednesday...however minimum afternoon humidity values will
mostly be above 30 percent with cold temperatures in place.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Storm Warning until 5 AM MST Tuesday for WYZ112-114.

     Winter Weather Advisory until 5 PM MST this afternoon for WYZ110-
     111.

NE...Wind Advisory until 3 PM MST this afternoon for NEZ054-055.

&&

$$

UPDATE...RE
SHORT TERM...ZF
LONG TERM...CLH
AVIATION...RJM
FIRE WEATHER...ZF



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