Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 130134

Area Forecast Discussion
National Weather Service Billings MT
634 PM MST Tue Dec 12 2017

Water vapor imagery shows NW flow aloft with a shortwave dropping
thru southern Alberta and Saskatchewan. Plenty of high clouds
exist over our cwa and have raised sky grids accordingly for the
evening. We will see clearing skies overnight. Dry conditions will
prevail outside of a possible sprinkle or flurry over the
mountains. As for wind, winds have decreased along our western
foothills as pressures are now rising east of the divide. Have
cancelled all wind highlights, with expectation of 30-40 mph gusts
for the rest of tonight, highest this evening. We will see an
increase in frontal winds at Sheridan this evening, and in fact
that is already starting to occur with gusts in the 20s. Could see
some 40 mph gusts in exposed areas along the eastern slopes of
the Bighorns, but low level lapse rates do not appear steep enough
to cause more of an issue, and mid level will begin to decrease
by late evening. Will see gusty NW winds develop across our
eastern plains as well, especially over the hills. JKL


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

Shortwave responsible for the very warm and windy conditions this
afternoon was moving SE into southeast Alberta this afternoon.
Pressure rises were slowly nosing down the Rockey mountain front
and were lessening the winds along the mountain foothills
northwest of our region in locations like Great Falls. These will
push through to our mountain foothills later tonight which should
put an end to the very strong winds in Livingston, Big Timber, and
other foothill locations. In and east of Billings and towards the
Dakotas border, these winds will take a little time to subside as
a strong push of northwest winds along and ahead of the shortwave
keeps conditions breezy through 3am tonight. Fire concerns will
slowly alleviate through the night as relative humidities recover
and winds slowly diminish.

Cooler conditions are anticipated Wednesday afternoon as heights
lower across the region. Another weak shortwave will move through
western Montana through the day. The best chance for precipitation
with this system will be in the mountains and nearby foothills
from Big Timber west and over the Beartooth mountains. Expect the
low levels to see rain and the mountains could see around an inch
of new snow above 6/7000 feet. High temperatures across the region
will be in the mid to upper 40s. Thursday will be another
relatively quiet day with high temperatures in the mid to upper
40s again. Could see another increase in our winds along the
mountain foothills into Friday morning as pressure gradients
increase along our mountain foothills. Dobbs

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

No major changes to the extended. The main time period of concern
is the precipitation mainly on Saturday as a shortwave begins
breaking down the ridge. The GFS, with a higher resolution, is
still showing more limited precip, mainly in the higher terrain.
The EC is still going with a more widespread precip event. Have
continued the higher PoPs in the mountains with mainly chance PoPs
elsewhere. Sunday looks like another potential windy day for much
of the area behind the departing shortwave. Winds around
Livingston still are potentially in wind advisory range.
Temperatures will continue to be warmer than normal through the

Farther out the general trend has continued with the pattern
changing to colder and snowier pattern. The EC is still not bring
as much cold air into the area. The GFS continues to show
temperatures dropping below 10 degrees for highs. Will continue
to monitor these changes as we approach the Christmas travel time.



VFR conditions will continue into Wednesday across the area.
Expect breezy conditions around KLVM, K6S0, and KBIL, with gusts
of 20 to 30 knots possible overnight. Winds around KMLS and KSHR
remain breezy overnight. AAG



    Wed     Thu     Fri     Sat     Sun     Mon     Tue
BIL 036/046 031/046 032/053 031/042 025/046 031/046 028/045
    00/B    10/U    00/B    33/O    11/B    11/B    12/O
LVM 034/039 028/043 031/047 030/038 025/041 032/043 031/044
    04/O    10/U    01/N    43/O    11/N    22/O    32/O
HDN 033/047 028/044 027/054 029/042 023/046 028/047 025/047
    00/B    11/U    00/B    43/O    11/U    12/O    12/O
MLS 033/044 028/038 025/051 029/041 023/044 028/043 025/045
    00/N    32/S    10/B    23/O    11/U    11/B    11/E
4BQ 035/044 029/039 025/053 029/041 023/045 029/045 025/046
    00/N    32/S    10/B    23/O    11/U    11/B    11/B
BHK 030/037 025/033 021/047 025/037 020/041 025/041 022/041
    01/N    43/S    00/B    22/O    11/B    11/B    11/E
SHR 034/045 027/042 024/055 027/040 020/045 025/047 023/047
    00/N    22/S    00/B    34/O    21/U    12/O    11/B




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