Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 231556

Area Forecast Discussion
National Weather Service Billings MT
856 AM MST Mon Jan 23 2017

Fog continues to advect/expand to the south/southwest and is
affecting Billings as well as parts of southeast MT. Miles City,
Baker and Forsyth have been showing visibility to a half mile or
less for a few hours now, and web cams confirm the widespread
nature of the fog. Have messaged the fog impacts thru social media
and issuance of SPS to midday. Will likely see areas of fog/
stratus through the afternoon as winds trend toward an upslope
direction and surface high builds from the north. As for
precipitation, not much going on now except for what looks like a
little light snow in our north central parts. Snow will expand as
upslope and low level moisture deepen over time later today into
this evening, and as Pacific trof moves into the central Rockies.
Will evaluate 12z runs for accums a bit later and will make no
changes at this time. Winter wx advisories exist for our southern
upslope areas beginning 00z. JKL


.SHORT TERM...valid for Tdy and Tue...

Seeing areas of dense fog this morning on IR satellite imagery.
Expecting fog to develop and persist from central Yellowstone
County through Miles City and Baker. Increasing upper-level clouds
will limit the intensity of the fog over Yellowstone, but
expecting fog to remain dense into the early afternoon over the
northeastern Plains.

A storm system begins to push into Beartooth/Absarokas this
morning. Upslope flow deepens and extended from Red Lodge
foothills to about Billings by late afternoon. Snow spreads
eastward Monday night and Tuesday.

Models have continued to trend weaker with this system and we have
lowered snow totals especially for areas such as Livingston and
Billings where 1 to 3 inches is likely. Thinking the big winners
for this event will be the areas where we see persistent upslope
through Monday night such as Red Lodge Foothills, southern
Bighorn County, and Sheridan County. Winter Weather Advisory
highlights have been pushed out this package for Monday night
through Tuesday afternoon.

Held off on Winter Weather Advisories for Powder River and Carter
for now. Right now we have around 4 inches of snowfall for those
areas but the trends have been lower with each run of the global
models, so we will let the day crew make the decision for those
areas. Bottom line, travel conditions will worsen especially over
southeastern Montana and northern Wyoming by Monday evening. Those
of you who will be traveling on Monday evening through Tuesday
should keep advised of the latest road conditions for those areas.
Additional factor to consider for the eastern Plains and northern
Wyoming will be the increasing winds on Tuesday afternoon which
could cause some impacts from blowing snow.

Only a slight chance of snow on Tuesday night and Wednesday as our
storm system slides into the central U.S.. Temperatures will fall
into the single digits for most of the area by Wednesday morning.

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

Model ensemble spreads for 850 MB and thickness are quite narrow
through Thursday, so confidence is high in temperature forecasts
up to this point. However, spreads quickly widen Friday and
beyond, but do indicate an overall warming trend. Thus, just how
much we warm up at the end of the week is still in question.

Looking at precipitation, residual moisture and strong cyclonic
flow aloft will result in isolated to scattered snow showers over
our CWA at midweek. However, toward the end of the work week an
amplified west coast ridge flops over the divide resulting in
drier and stable air through the weekend. That said, the pattern
will be favorable for strong winds (highest in the western zones)
Friday and through the weekend. BT



Fog and low stratus are expected to persist across east central
sections of Montana today including KMLS and KBHK. MVFR, IFR and
LIFR cigs and vsbys are possible. For the rest of the area, expect
VFR ceilings to prevail most of the day though area mountains may
become obscured as snow showers increase over the higher terrain
through the day. After 21Z, MVFR to IFR conditions with light snow
will spread over the lower elevations generally from west to
east. BT/Hooley



    Tdy Tue     Wed     Thu     Fri     Sat     Sun
BIL 027 016/024 010/027 013/027 016/032 018/035 023/038
    3/J 76/S    12/J    10/B    00/N    00/N    00/N
LVM 032 012/026 009/027 011/026 011/031 016/035 021/041
    4/J 64/S    22/J    10/N    00/N    00/N    00/N
HDN 025 011/023 001/025 007/025 009/030 009/031 015/036
    2/J 86/S    22/J    10/B    00/B    00/U    00/B
MLS 024 012/021 005/021 006/022 009/028 012/030 016/034
    2/J 44/S    22/J    20/B    00/U    00/U    00/B
4BQ 027 014/023 005/023 007/024 011/029 013/032 018/037
    2/J 88/S    22/J    20/B    00/N    00/U    00/B
BHK 024 012/019 006/019 004/020 007/026 012/029 016/034
    2/J 44/S    22/J    20/B    00/N    00/B    00/B
SHR 028 011/022 003/024 005/026 008/031 012/035 017/040
    2/J 98/S    22/J    10/B    00/U    00/U    00/B


MT...Winter Weather Advisory in effect from 5 PM this afternoon to
      2 PM MST Tuesday FOR ZONES 38-56-66.
WY...Winter Weather Advisory in effect from 5 PM this afternoon to
      2 PM MST Tuesday FOR ZONES 98-99.


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