Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 200402

Area Forecast Discussion...Updated
National Weather Service Billings MT
902 PM MST Thu Jan 19 2017

Light precipitation falling over the central portion of the
forecast area is mainly a very light rain given temperatures are
still in the mid 30s. Precipitation has advanced very little
eastward so not concerned about any local freezing rain where cold
air has developed over Miles City and Sheridan areas. Despite
radar showing some stronger returns north of Billings melting
layer algortihims indicate this is likely wet snow flakes changing
to rain so do not believe precipitation is much heavier north of
town. Chances for precipitation reaching the ground increase
overnight as the airmass becomes more saturated and still suspect
a change to snow will occur given opportunity for evaporative
cooling. no updates to current forecast. borsum


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

Gap winds continue to gust to around 50 mph in Livingston DOT
station, as Pacific trof moving inland seems to have slowed a bit.
Winds should taper off later this afternoon/evening as trof
proceeds eastward.

The bulk of changes to the short term forecast centered around
slight adjustment in pops to slow progression eastward across the
west this evening. Otherwise...the best chances across the west
and central zones appear to be between about 03z and 09z Friday
morning. System will proceed east and northeast...with jet streak
shifting quickly northeast on Friday morning. Some energy does
linger...but much of upper level lift is defendant on jet

Uncertainties remain regarding breakdown of precip type...and
timing of changes...however chances for freezing rain appears
less likely. Although all dynamics appear to be in the mid and
upper level...resulting in precip forming higher in atmosphere
and falling through a warmer layer of air to reach the surface.
Higher dewpoints at the sfc...resulting from snowmelt/evaporation
across the region...should limit freezing rain potential...pointing
toward better potential for wet snow and/or rain/snow mix.
Therefore...wet/slushie roads refreezing overnight and remaining
slick for the Friday morning commute is of greatest concern at
this time. Additionally...this will not be a cold system...which
further favors mixed precip.

Have continued with snow amounts of 2 inches or less in
west/central parts, with 3-5 over the mountains. We will need to
monitor surface temps and potential areas of enhanced
frontogenesis with this event as precip begins to move across the
region. Snow appears to linger in the east into Saturday...based
on slightly slower progression of trof across the region...but
will amount to little in the way of precip. Meanwhile shortwave
ridging sets up over west and central zones.

Temperatures will be cooler the next couple of days, with 30s on
Friday and Saturday. AAG

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

Upper trof dominates over the west coast Sunday and Monday with
weak W-SW flow aloft pushing mid level moisture and a few weak
disturbances through the area. This will produce mainly mountain
snow showers. With jet to the south and cross mountain flow fairly
weak will see temperatures around freezing for highs Sunday,
dropping into the 20s on Monday. Core of energy from the west
coast trof will slide east across Wyoming late Monday and Tuesday
producing a period of better precipitation chances across the area
with QG forcing and favorable upslope winds. A lobe off the Hudson
Bay Low drops south behind the Pacific system for
Wednesday/Thursday keeping temperatures about 10 degrees below
normal along with a chance for snow showers, especially over SE
MT. Chambers



Wind gusts in the western foothills will continue to weaken this
afternoon from gusts in the 40kt range to gusts in the 25kt range
by 01z. Pacific moisture and a weak cold front will bring MVFR
ceilings to areas west of a Miles City to Broadus line tonight,
with local IFR conditions in a mix of rain/snow anticipated
especially after 07z. There is a very slight chance of light
freezing rain for these areas as well tonight, including KLVM,
KBIL, and KSHR taf locations. Expect flight conditions to improve
late Friday morning as precipitation tapers off. Chambers



    Fri     Sat     Sun     Mon     Tue     Wed     Thu
BIL 030/037 019/031 020/032 015/027 017/026 014/025 013/028
    76/W    20/U    11/B    12/J    53/J    22/J    11/B
LVM 026/039 014/037 018/037 017/033 012/028 010/028 011/028
    65/W    21/B    21/B    22/J    42/J    22/J    11/B
HDN 024/035 012/029 010/031 006/026 012/025 007/024 007/026
    56/W    20/B    11/B    11/B    53/J    22/J    21/B
MLS 022/036 020/029 014/029 007/024 010/023 008/023 008/025
    12/W    32/J    11/B    11/B    32/J    22/J    21/B
4BQ 018/036 017/032 012/032 005/026 010/025 009/024 007/026
    14/W    32/J    11/B    11/B    43/J    22/J    21/B
BHK 018/034 021/031 014/028 007/023 009/023 010/022 009/023
    02/W    22/J    21/B    01/B    32/J    22/J    22/S
SHR 020/034 011/031 010/033 008/028 011/025 006/025 006/027
    36/W    30/B    11/B    12/J    53/J    22/J    21/B




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