Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 081045

Area Forecast Discussion
National Weather Service Billings MT
345 AM MST Thu Dec 8 2016

.SHORT TERM...valid for Tdy and Fri...

Active weather pattern in store across our forecast area through
the short term and beyond. A strong jet stream is progged to move
onshore across the Pacific northwest and move eastward across the
northern Rockies today into Saturday. This flow will also bring
abundant Pacific moisture across these areas as well, with nearly
continuous snow for the mountain locations across Idaho, as well
as western Montana and Wyoming.

Models keep things precip-free today with the exception of some
mountain snow showers. However, by tonight a disturbance within a
northwest flow aloft will bring increasing snow shower chances for
our western areas mainly west of Billings overnight and spreading
east toward Miles City during the day Friday. Dynamics are not
strong with this system with accumulations looking to be around a
half inch for the above mentioned areas with a couple inches for
the Beartooth/Absaroka Mountains.

Models then bring a stronger disturbance across the forecast area
Friday night along with Pacific moisture overrunning the current
arctic air in place. The GFS is snowier than the ECMWF, but both
models bring snow across the western and central portions of the
forecast area. The best chances look to be along and north of a
Livingston- Billings-Forsyth line where accumulations could be in
the 2-4 inch range. As a result, I did increase precip chances to
likely for these areas Friday night. However, we will hold off on
any advisories given the event is 48 hours out and there remains
some uncertainty.

Temperatures will again be in the single digits to lower teens
today and Friday. Although there are some indications the arctic
may retreat briefly across the Beartooth/Absaroka foothills where
temperatures may reach the 20s on Friday. Hooley

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

On Saturday, warm/moist air overrunning the arctic air looks to
bring some light snow to the area...but with westerly 700 mb winds
think that downsloping is going to dry out the lower atmosphere
some. Could receive some light snowfall amounts (generally less
than an inch over the plains and a few inches over the
Beartooth/Absaroka/Bighorn Mountains).

A shortwave ridge over the northern Plains should then propagate
eastward Saturday night...which should help to push the surface
high associated with the arctic air mass to the east. This
changing surface pressure pattern should allow our surface winds
to turn southwesterly. These winds should bring in relatively
warmer air that has been sitting to our southwest late Saturday
night into Sunday. High temperatures on Sunday could approach the
freezing mark in the lower elevations of south central MT and
north central WY...teens for eastern MT where arctic air will
linger a little longer.

For Sunday night into arctic front looks to drop
southward across MT...plunging temperatures again. A period of
light snow is possible with the front late Sunday night into early
Monday, although the timing is a bit uncertain at this lead time. The
arctic air mass then largely looks to stay entrenched through
next Thursday with some fluctuations in temperatures day-to-day as
waves rotate through upper cyclonic flow centered over Canada.
The Tue.-Thu. period looks mostly dry as upper ridging should
suppress most precipitation development, though a stray snow
shower cannot be ruled out if a wave travels close enough to the
area. RMS/Hooley



Most of the region will see VFR conditions and light winds today.
Locally lower ceilings may be encountered near KBIL due to
industrial activity near the airport. A band of occasional MVFR
cloud cover will persist along the eastern state line into the
afternoon as well, including the KBHK vicinity. RMS/Hooley



    Tdy Fri     Sat     Sun     Mon     Tue     Wed
BIL 005 904/008 004/018 008/026 005/011 000/015 004/019
    1/U 23/S    64/J    22/J    34/J    31/B    11/B
LVM 010 001/023 016/029 019/030 013/018 002/017 008/023
    1/U 44/S    65/J    32/J    34/J    23/J    22/J
HDN 008 000/013 007/017 006/026 003/014 903/015 000/019
    1/U 12/S    44/J    22/J    34/J    21/B    11/B
MLS 003 906/005 901/008 903/018 000/007 906/011 901/014
    0/U 02/S    64/J    22/J    34/J    21/B    11/B
4BQ 006 905/010 004/015 003/025 003/013 903/014 002/018
    0/U 01/E    34/J    22/J    33/J    21/B    11/B
BHK 001 913/003 904/006 906/015 902/004 907/008 902/011
    0/B 01/E    34/J    22/J    22/J    21/B    10/B
SHR 010 902/016 009/023 009/027 004/014 903/012 002/020
    1/U 11/B    24/J    22/J    23/J    32/J    11/B


MT...Wind Chill Advisory in effect until 11 AM MST this morning
      FOR ZONES 33-37.


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