Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 110147

Area Forecast Discussion
National Weather Service Billings MT
647 PM MST Tue Jan 10 2017


Made a quick update this evening due to deteriorating conditions
in Judith Gap area. Chose to upgrade highlight in that area to a
Blizzard Warning as wind gusts are approaching 50 mph...creating
severe blowing and drifting snow. Highway 191 has already been
closed through that area due to poor visibility and dangerous
driving conditions.

Along with upgrade of the highlight, associated forecast
grids were updated to reflect current conditions, and expected
continuation of conditions, in and around Judith Gap. Changes
centered mainly around strong gusty winds and chances for blowing

Otherwise the inherited forecast appears to be in good shape. AAG


.SHORT TERM...valid for Wed and Thu...

Period of increased snowfall expected across the western half of
the area tonight as a wave moving onto the Pacific Northwest coast
brings lift to the area and tightens a baroclinic zone over the
area as a reinforcing shot of arctic air moves into the area from
the north. This band of snow continues into Wednesday as energy
from the wave moves across southern Montana and northern Wyoming
augment by upslope pressure gradients. Have not changed snowfall
amounts much and most soundings look like dendritic growth regions
will be not too deep so do not expect real rapid accumulations or
reductions to visibility. May be some localized blowing snow as
the high builds in tonight so current advisory looks good with
the warning in the mountains continuing with westerly aspects more
likely to see the heaviest snow tonight.

As the cold air deepens on Wednesday it will limit accumulations
for areas north and east of Billings but locations west of
Billings like Big Timber and along the foothills will see higher
amounts. Do not think any lower elevation accumulations will
exceed 8 inches in the above mentioned areas but will have to
watch snowfall intensity this evening to see if this remains on

Wednesday will be a cold day as the arctic air is entrenched over
the area but the core of the high pressure will retreat eastward
on Thursday. Still cyclonic flow aloft over the western half of
the region so lack of a real cold pooling of high pressure west
and south of the continental divide will limit development of
westerly winds. Otherwise looks mainly dry and cold bet some
mixing overnight will keep Thursday night temperatures warmer.

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

No major changes were needed for the extended period beginning on
Friday. The overall trend in the weather pattern will bring a
welcome change for most folks. The forecast trend will bring
increasing heights, and accordingly, warmer air to the region. The
only issue through the extended period will be the winds, and a
chance for blowing this weekend in zones west of Billings.

Winds should increase across Livingston, Nye, and Big Timber on
Saturday morning as weak disturbances passing overhead in the
westerly flow induce pressure falls across the Plains through the
weekend. With temperatures expected to remain below freezing
until at least Sunday afternoon, blowing snow will likely cause
issues until then. It appears that the strongest winds and
blowing snow threat will be overnight Saturday and into early
Sunday morning. After a brief reduction in the winds on Sunday
night, well see the winds pick up again on Monday. Mid level flow
looks a bit faster at the beginning of next week so stronger
winds are certainly a possibility. Dobbs



Conditions will gradually deteriorate late this afternoon as snow
showers overspread the region with widespread IFR conditions.
Brief periods of LIFR cigs/vis are possible in the heavier bands.
As the arctic front moves south overnight. Snow will gradually
thin with improving conditions after 12/18z Wednesday. Dobbs


    Wed     Thu     Fri     Sat     Sun     Mon     Tue
BIL 904/007 904/012 004/024 010/028 016/033 020/036 022/038
    94/S    21/B    00/U    00/U    00/N    00/N    11/N
LVM 001/014 000/024 007/028 010/031 016/036 019/040 025/041
    97/S    31/N    00/Q    00/Q    01/Q    10/N    11/N
HDN 907/007 911/014 902/022 901/025 007/030 011/033 013/036
    84/S    21/B    00/U    00/U    00/U    00/B    01/B
MLS 913/002 916/007 905/021 903/024 008/028 011/033 019/035
    61/B    11/U    00/U    00/U    00/U    00/U    01/U
4BQ 907/009 912/013 000/023 901/026 008/031 012/033 016/036
    63/S    21/U    00/U    00/U    00/U    00/U    01/U
BHK 912/001 913/005 909/019 000/024 008/028 011/031 017/036
    61/B    11/U    00/U    00/U    00/U    00/U    01/B
SHR 905/008 904/018 000/026 001/030 006/035 010/038 016/040
    66/S    42/J    00/U    00/U    00/U    00/B    01/U


MT...Winter Weather Advisory in effect until 11 AM MST Wednesday
      FOR ZONES 28>31-35-42-57-58.
     Winter Weather Advisory in effect until 5 PM MST Wednesday
      FOR ZONES 34-38>41-56-64>66.
     Blizzard Warning in effect until 11 AM MST Wednesday FOR ZONE
     Winter Storm Warning in effect until 6 AM MST Thursday FOR
      ZONE 67.
WY...Winter Weather Advisory in effect until 5 PM MST Wednesday
      FOR ZONE 99.


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