Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 090314
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
814 PM MST Thu Dec 8 2016

.UPDATE...

Clear skies, light winds, snow cover and arctic high pressure
combining for plummeting temperatures over eastern zones this
evening. Already -14 in Baker and near to below zero in many other
locations. HRRR seems to have caught on to the areas of snow cover
this evening showing a good contrast between snow and no-snow
areas in the temperature field so trended temperature forecast
toward it. With increasing cloud cover spreading west to east
overnight expect the temperature drop to end shortly after
midnight with steady or slowly rising temperatures toward sunrise.
Isolated to scattered snow showers should develop around midnight
over western zones and shift eastward with mid level warm
advection increasing. Falling pressures west of the divide
inducing easterly low level flow east of the divide should enhance
lift in the foothills where the best pops are. No big changes to
the precipitation forecast this evening. Rest of the forecast is
in good shape. Chambers

&&

.SHORT TERM...valid for Fri and Sat...

Snow chances will increase over the next 24 hours to 36 hours. An
approaching shortwave, along with moisture associated with an
Atmospheric River, will move into the area. Tonight into Friday
morning, most of the snowfall will be over the mountains. Winds
across the area will be lighter tonight, so wind chill issues will
be very marginal. For now will not issue any highlights.

Friday will see the moisture, and therefore chances for snowfall,
slowly spread east and into lower elevations. This will result in
an extended period of light to moderate snowfall through Saturday.
The best chance for snowfall will be Saturday morning as the best
push of energy and moisture moves through. The complicating factor
for the snow amounts will be a push of westerly winds during the
day on Saturday. Not only will this reduce the snowfall with
downslope flow, it will also bring warmer temperatures. Given the
finer scale nature of where that boundary will be, there is still
some model discrepancies with the placement. For now will not have
an advisory, but this will continue to be monitored. Reimer

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


Sunday will feature the warmest day across the forecast area as
west and southwest flow aloft, and at the surface, move in. This
will help erode the arctic air mass in place and get temperatures
back into the 30s in all locations but extreme eastern zones near
Miles City, Baker, and Ekalaka where mid to upper 20s are
expected. A large upper level low will be on the US doorstep
early Sunday night so dont expect the warmup to last long. If this
low moves in earlier expect less erosion of the air mass and
cooler temperatures Sunday. Some snow showers are possible over
the higher terrain with isolated snow showers expected over the
plains.

The aforementioned upper level low dives southeast on Monday
morning...driving another strong arctic front through the region.
Models are fairly consistent in developing a band of snow that pushes
south along and behind the front so folks should be ready for a
quick shot of 1-3 inches of snow Monday. Some residual snow
showers could stick around in southern zones, and along the higher
terrain Tuesday, but model uncertainty is high with regards to
snow (some solutions keeping light snow showers around the region)
but are in agreement on cold temperatures in the single digits
and teens.

Cold temperatures continue Wednesday and Thursday but model
uncertainty increases towards Fri and next weekend. The trend at
this point seems to indicate another round of cold air and snow
returning late Thursday into Friday. Dobbs
&&

.AVIATION...


An approaching disturbance from the west will bring some snow and
MVFR/IFR restrictions to KLVM after 06z. Expect these lower cigs
and vicinity snow showers to spread east to KBIL after 12z. KSHR
and KMLS should remain VFR with wave passage. Expect brief period
of VFR conditions to return after 18z at KBIL and KLVM and before
MVFR/IFR conditions potentially return after 00z Friday.
Dobbs/Chambers

&&

.PRELIMINARY POINT TEMP/POPS...

    Fri     Sat     Sun     Mon     Tue     Wed     Thu
-----------------------------------------------------------
BIL 903/008 005/019 012/031 006/016 901/010 003/016 001/009
    24/S    54/S    22/J    34/J    31/B    11/U    12/J
LVM 903/020 015/030 021/030 016/024 000/012 003/018 004/011
    35/S    65/S    32/J    34/J    22/J    11/B    24/J
HDN 901/011 006/017 008/032 006/014 902/012 902/015 901/012
    12/S    44/S    22/J    34/J    21/B    11/U    12/J
MLS 907/005 901/009 000/026 002/007 907/007 902/012 905/006
    02/S    65/S    22/J    33/J    21/B    10/B    02/J
4BQ 907/009 002/016 006/030 005/014 904/009 000/015 902/010
    01/E    33/S    21/B    23/J    21/B    00/B    02/J
BHK 918/003 905/007 903/020 902/003 907/004 903/008 906/004
    01/E    45/S    22/J    22/J    21/B    00/B    02/J
SHR 910/014 008/024 012/030 013/017 905/007 901/015 000/012
    01/B    24/S    22/J    23/J    20/B    10/U    12/J

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.

&&

$$
weather.gov/billings


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