Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 220354

Area Forecast Discussion...Updated
National Weather Service Billings MT
854 PM MST Sat Jan 21 2017

Fog redeveloping across portions of southeast Montana and in a few
areas it never fully cleared out today. Further west winds are
keeping temperatures a bit warmer so any fog that forms may be
patchy in nature. Current forecast covers trends well and no
update expected. borsum


.SHORT TERM...valid for Sun and Mon...

Quiet day across the region...with generally light winds. The
quiet pattern will persist through Monday...with 500mb ridging
building through the weekend...and next weather system moving into
and across the region Monday night.

Southwest flow sets up over the region tonight...bringing Pacific
moisture into the Absarokas...resulting in scattered snow
showers. Showers are not expected to reach the plains. Daytime
snowmelt and rapid radiational cooling overnight point to fog
across eastern zones again tonight...with some patchy fog possible
for central zones as well. Central zones may see some stratus
development later this evening which would limit fog
potential...but early morning clearing may still allow some
localized development.

A weak shortwave in the Pacific flow slides into the CWA Sunday
evening...bringing a bit better chance of snow to the high
terrain...and slight chance into the western plains/foothills. Any
precip is expected to be minimal...due to dry air at lower continued with lower pops.

A closed off Pacific low makes its way into eastern Idaho by
Monday evening...and southwest flow spreads east...spreading snow
across western and southern zones. The broad Pacific trof remains
over the region through the night...with closed low shifting
quickly east...and into southwest South Dakota by Tuesday morning.
This system will spread snow across the region through the
night...with greatest accumulation across the southern tier of the
region. This system is moving pretty quickly...limiting snow
accumulation at this time...but wouldn`t take much of change in
path and timing to make drastic changes to impacts. AAG

.LONG TERM...valid for Tue...Wed...Thu...Fri...Sat...

Storm system Monday night will continue into Tuesday as the upper
low pushes southeast of the area. Lingering upslope flow will keep
most intense snowfall over the north facing foothills in the
morning, shifting into far southeast MT in the afternoon before
snow tapers off Tuesday evening. General QPF amounts for the
system currently range from a tenth of an inch over northern zones
to around 4 tenths in the south. This equates to 1 to 2 inches of
snow north and 4 to 6 inches south with locally heavier
accumulations possible. Overall track of the system hasn`t changed
much in the past 12 hours, but still enough of a spread that
snow accumulations could change +/- several inches. In addition to
the snow, tightening pressure gradient will bring some blowing
snow into the picture Tuesday into Tuesday evening over southern
and eastern zones. Not enough certainty for a watch at this point
but will probably need some winter highlites with this system,
most likely south of a Livingston to Billings to Ekalaka line.
Those with travel plans late Monday through Tuesday night should
pay close attention to the forecast the next 36 hours, especially
anyone heading to the south.

Northerly unstable flow persists Wednesday into Friday with cool
temperatures and a chance of snow showers, though nothing heavy.
Ridge aloft over the west coast tries to spill into the area by
late Friday with drier and warmer air for the weekend. Some
periods of gusty west to northwest winds can be expected from
Friday through the weekend as well. Chambers


VFR conditions will prevail through this evening, though isolated
areas of fog will persist in river valley locations across
southeast Montana. By late tonight expect fog development to
become widespread again from Billings east, including KMLS and
KBHK. Cloud cover will work against fog development at KBIL but it
will be close by, the same for KSHR. Areas with fog will be IFR or
lower with some locations VLIFR at under a 1/4sm visibility.
Western mountains will see snow showers through tonight with
periods of obscuration. Chambers


    Sun     Mon     Tue     Wed     Thu     Fri     Sat
BIL 020/032 017/028 018/024 010/025 011/025 017/031 020/033
    00/U    12/S    76/S    22/J    11/U    11/N    00/N
LVM 019/038 019/034 014/024 009/025 008/022 013/029 015/032
    21/B    24/S    76/S    22/J    11/U    22/J    11/N
HDN 010/030 009/026 012/024 003/024 007/022 012/029 012/031
    00/U    02/S    76/S    22/J    21/B    11/B    00/U
MLS 013/028 010/024 013/023 008/020 004/019 009/027 016/030
    00/B    01/B    55/S    22/J    21/E    11/B    00/U
4BQ 013/032 009/027 013/022 007/021 005/019 008/027 014/030
    00/U    02/S    77/S    22/J    22/J    11/B    10/U
BHK 015/027 009/025 013/021 010/018 005/017 006/025 014/028
    00/B    01/B    46/S    32/J    22/J    11/B    10/U
SHR 012/033 012/029 011/022 006/023 005/021 010/030 012/033
    00/U    02/S    77/S    22/J    21/B    11/B    10/U




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