Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 291641
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
941 AM MST Tue Nov 29 2016

.UPDATE...

Updated winter storm highlites to cancel Winter Weather
Advisories for Sheridan county, Southern Big Horn county, and
Rosebud county. Downgraded Winter Storm Warning for Custer and
Powder River county to an Advisory through midnight tonight. Left
Winter Storm Warning in place for Fallon and Carter counties.

Strong storm system continues to rotate over far eastern North
Dakota this morning wrapping snow and wind back into the area.
Heaviest snowfall looks to be over for the area with lingering
snow bands working through areas east of Billings over toward
Miles City, and more persistent light snow for far eastern zones.
Picked up 5 to 7 inches of snow according to early reports over
the warned area overnight. Northerly winds gusting 35 to 50 mph
will continue to produce significant blowing and drifting of this
snow today in areas with continued warnings and advisories.
Further west the light snow on the ground and light additional
accumulations should present only a nuisance impact so highlites
have been cancelled in these areas.

Have seen some fairly intense but shortlived snow shower activity
over western foothills and mountains this morning. latest models
indicate this activity should diminish through the day. Increased
morning and early afternoon pops to account for this. Travelers
should be prepared for some tricky road conditions for the
Paradise Valley and I-90 from Livingston over Bozeman Pass.

Dakotas storm system should begin to pull eastward this afternoon
allowing improving conditions through the day from west to east.
Chambers

&&

.SHORT TERM...valid for Tdy and Wed...

The strong winter storm over the Eastern Dakotas was beginning to
weaken as it moves southeast. Light snow, along with bands of
heavier snow, were continuing to wrap around this storm into
eastern Montana. Winds have been elevated all night, allowing
falling snow to quickly turn into blowing snow. This has caused
slick roads, some drifting snow, and reduced visibilities on areas
roads in the east. Across western zones near Livingston,
Melville, and Big Timber, light snow showers were associated with
a weak wave moving overhead. Accumulations with this wave will be
light and will primarily be confined near the higher terrain.

In regards to the winter storm to east, we are still expecting
the heaviest snows to be early this morning across eastern Montana
and this is when the impacts will be the greatest. Drier air
across central Montana will filter south and east through the day
as the storm system shifts off to the east. This dry air is what
has kept many locations from Billings-Reed Point-Harlowtown-
Roundup mostly dry. Some of this dry air has already filtered
south this morning, helping to lighten some of the snow over the
Pryors, Bighorns, and to a lesser extent, Sheridan county. By this
afternoon much of the snow should be ending in locations like
Miles City, Forsyth, Lame Deer, and Sheridan as the drier air
moves in and the upper level support slowly wanes. By later this
evening we should see the snow ending over the rest of eastern
Montana as the drier air progresses east. With the strong
northwest flow in place can`t rule our some mountain aided snow on
our north and northwest facing slopes over the Beartooths, Pryors,
and Bighorns, but we expect much lighter snow in the afternoon
compared to the morning hours.

Minimal changes were needed to the snowfall forecast. We still
expect an additional 1-3 inches of snow across eastern Montana,
and 0-2 inches across the higher terrain in the Pryors, Bighorns,
and north facing slopes of Sheridan county through the rest of
today. The biggest hazardous from the snow today will be slick
roads, reduced visibilities due to blowing snow (even after the
snow has ended), and high winds across the entire forecast area.
We expect to see peek wind gusts across the region around 35 to
45 mph this morning and early afternoon, especially in Carter,
Powder River, and Sheridan Counties where some 50 mph gusts are
not out of the question. While the winds will lessen as the
snowfall ends today folks should still expect 25 to 35 mph winds
through the evening hours. Cold temperatures in place across the
east will still allow patchy areas of blowing snow through the
evening hours before winds lessen further late tonight. With this
in mind, and little melting of snow on roads, we encourage users
to take extra caution on area roads, and always re-check the road
conditions before heading out.

Conditions will remain mostly quiet on Wednesday as high pressure
moves into the forecast area. A weak wave is expected to move over
the region late Wednesday night into Thursday, possibly
generating some light snow showers over the western terrain and into
central zones such as Billings. Dobbs

.LONG TERM...valid for Thu...Fri...Sat...Sun...Mon...

Most of the changes in the extended period were early next week.
Thursday still looks like a shortwave moving through western
Montana. As the moisture and energy moves across the western
mountains, they will see a chance for some snow. The majority of
the precip will be over the higher terrain, leaving the plains
dry. Friday a weak ridge will try to build in, but the main axis
will be titled. This will leave the area in more of an unstable
northwesterly flow. Through the weekend this unsettled flow will
result in chances for snow, or a rain snow mix in the lower
elevations, with the best chances over the mountains.

Early next week, models are shifting back towards more of an
arctic solution. Thus have trended temperatures down, mainly
opting towards more of the unbias-corrected guidance. At this
point there is still plenty of uncertainty in the guidance, but
the overall trend in the ensembles is for cooling temperatures.
Reimer
&&

.AVIATION...

VFR conditions will prevail west of a Hysham to Sheridan Wyoming
line today, with isolated MVFR conditions near snow showers. To
the east expect MVFR to IFR conditions the further east you go.
Northwest Winds gusting 30 to 45 kts can be expected from
Billings east through early evening. Expect overall conditions to
improve from west to east this afternoon through tonight as strong
storm system over the Dakotas moves eastward into the Great Lakes
region. Chambers

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Wed     Thu     Fri     Sat     Sun     Mon
-------------------------------------------------------
BIL 038 023/038 026/038 023/037 027/044 029/042 027/033
    2/W 10/U    22/S    21/B    12/W    22/O    23/S
LVM 035 022/036 027/036 021/035 028/043 030/042 027/030
    4/J 11/N    33/S    21/B    32/W    33/O    33/S
HDN 037 021/037 023/038 020/036 023/043 026/041 023/034
    3/W 10/U    12/S    21/B    12/W    22/O    23/S
MLS 034 022/034 014/034 018/034 021/044 023/040 021/032
    5/J 31/B    11/B    21/B    12/W    21/B    23/S
4BQ 032 019/035 013/036 016/032 018/042 021/039 019/033
    9/S 31/B    12/J    21/B    02/W    21/B    12/S
BHK 027 017/027 008/028 012/029 015/039 018/036 016/029
    +/S 53/J    11/B    21/B    13/J    21/B    13/S
SHR 030 017/034 014/034 014/031 015/040 021/038 019/032
    4/J 10/U    12/S    21/B    11/B    11/B    12/S

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory in effect until midnight MST tonight
      FOR ZONES 32-36.
     Winter Storm Warning in effect until 6 AM MST Wednesday FOR
      ZONES 33-37.
WY...None.

&&

$$
weather.gov/billings


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