Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 170942
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
242 AM MST Tue Jan 17 2017

.SHORT TERM...valid for Tdy and Wed...

Short term forecast remains in good shape so only a few
adjustments were made with this issuance. High pressure ridging
gets flattened somewhat today as a surface low moves across
southern Canada. This low combined with surface high pressure over
southeast Idaho will allow for the continued development of lee-
side troughing. Winds are currently gusting around 40 mph for the
Livingston area but the strong wind gusts have not yet
materialized. This is due to the fact that the pressure gradient
orientation has been more east/west instead of the preferred
north/south orientation perpendicular to the Paradise Valley. In
any case, winds will continue to be gusty with the stronger winds
arriving this evening and especially through the day Wednesday. As
a result, the wind advisory for the foothills areas from
Livingston to Nye will continue.

Mid and high level clouds will rotate around the periphery of the
ridge and move south out of Canada and across our forecast area
today with partly sunny skies prevailing. Temperatures aloft
continue to warm and these are expected to start mixing down today
and especially for Wednesday allowing most areas to warm above
freezing for the first time in several weeks. An upper low and
trough approach the Pacific northwest coast Wednesday allowing the
ridge to build once again over the northern Rockies. This
combined with downslope flow should bring the warmest temperatures
of the week with most areas across the lower elevations warming
into the 40s. Hooley

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

Warm temperatures will continue Thursday as flow backs to the
southwest with height falls in advance of a Pacific trof moving
into the Great Basin. Temps will not be as warm as Wednesday but
should still make it into the 40s most areas. Have scaled back
pops over our mountains on Thursday due to trofs later arrival.
Still looks like a fair chance of light precipitation for our west
to central parts Thursday night into Friday, with divergence in
RRQ of 100+kt H3 southerly jet, along with modest mid level
frontogenesis, though southern portion of splitting trof will be
well to our S/SE. Models not quite in agreement here in terms of
forcing and QPF, and overall have shifted best potential a bit
west from where it appeared yesterday. Thus, have lowered pops
across the eastern third of our cwa where it may remain completely
dry. Precipitation type still looks to be rain to wet snow as
850mb temps fall to near zero. GFS lifts a shortwave north of our
cwa by Friday night, whereas the ECMWF keeps troffing and some
light precipitation along convergent axis from near Harlowton to
Sheridan, so details still very much uncertain. In any event, have
kept some low pops through Friday night.

Models not in very good agreement Saturday through Monday.
Consensus is for some kind of troffing and weak flow aloft
Saturday, with a weak low lifting through the Dakotas, shifting to
a low amplitude ridge but with below normal heights as another
Pacific trof begins to move into the western CONUS Sunday and
Monday. Will keep some low pops thru these periods, but does not
look like anything too dynamic.

Temperatures will cool gradually Friday through Monday, with near
to slightly below normal values by the first part of next week. No
arctic air in sight.

JKL

&&

.AVIATION...

VFR conditions will prevail across the forecast area today and
tonight. Southwest to west winds will be gusty along the western
foothills today, with gusts of 35-45 kts at KLVM/K6S0/K3HT,
increasing to 50 kts at KLVM late tonight. Local drifting snow is
possible in these areas. Gusts to 30 kts will extend as far east
as KBIL. JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Wed     Thu     Fri     Sat     Sun     Mon
-------------------------------------------------------
BIL 042 031/047 032/044 028/038 020/033 020/033 017/030
    0/N 00/U    00/B    32/W    22/J    21/B    11/B
LVM 045 031/048 034/046 026/040 018/037 019/035 017/034
    0/N 00/N    02/W    53/W    22/J    21/B    12/J
HDN 039 024/045 025/041 021/035 016/031 014/031 010/028
    0/U 00/U    00/B    22/W    22/J    21/B    11/B
MLS 035 025/043 022/040 020/035 018/031 018/031 010/027
    0/U 00/U    00/U    11/B    12/J    22/J    11/B
4BQ 040 023/045 022/042 017/035 016/033 017/033 008/027
    0/U 00/U    00/U    11/B    22/J    22/J    11/B
BHK 036 024/038 020/041 021/034 017/032 017/030 011/028
    0/U 00/U    00/U    00/U    12/J    22/J    11/U
SHR 040 025/045 024/044 019/036 014/034 015/034 011/029
    0/U 00/U    00/B    12/W    22/J    21/B    11/B

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Wind Advisory in effect until 6 AM MST Thursday FOR ZONES
      65-66.
WY...None.

&&

$$
weather.gov/billings



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