Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 190339
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
839 PM MST Sat Nov 18 2017

.UPDATE...

Winds have been increasing across the gap flow areas this evening
as the surface pressure gradients tighten. The Wind Advisory in
effect for the Livingston area and Beartooth Foothills is on track
with latest observations showing winds gusting in excess of 50 mph.
Have adjusted sky cover and dropped temperatures across portions
of the area. Some locations such as Sheridan were already
approaching their forecast lows this evening. Low temperatures
will range from the upper teens to lower 30s tonight. Otherwise,
the rest of the forecast remains on track and the previous
forecast discussion and an updated aviation discussion are below. STP

&&

.SHORT TERM...valid for Sun and Mon...

For the rest of the weekend the story will be the wind as strong
pressure gradients develop across the mountain foothills. The Idaho
to Lewistown pressure gradients have increased through the
morning and afternoon hours. The winds we experienced this
afternoon were a combination of these increasing pressure
gradients and warm temperatures allowing us to mix into some of
the stronger winds in the mid-levels.

Moving into tonight, we will lose the effect of the mixing so
expect winds in much of the lower elevations east of Harlowton
and Big Timber to weaken some overnight. The winds will slightly
weaken this evening along the foothills before increasing again
overnight. While the gradient remains steady through tonight,
warmer air moving in over the mountain-tops, and winds beginning
to turn more to the southwest, will help increase the winds in
our gap locations such as Livingston, and Nye where wind gusts up
to 60 mph are possible tonight. Windy conditions will keep temps
warm in the foothills and generally in the low 30s. East of
Billings and the Bighorn mountains, expect cooler temperatures in
the mid 20s as less wind is anticipated.

Strong winds continue through Sunday afternoon and then increase
again overnight Sunday into early Monday as even stronger pressure
gradients and mid-level winds move into our foothill locations. Currently
expecting 60 to 70 mph wind gusts for our foothill locations in
Livingston, and Nye. Expect these wind gusts to persist through
Monday morning before a cold front approaches the forecast area
from the north by the early afternoon. This front will help
decrease the pressure gradients across the foothills through the
afternoon so only have the wind advisory going through noon on
Monday. The main cold front pushes through the region Monday night
bringing scattered rain/snow showers behind the front into
Tuesday morning. The mountains should get another shot of snow
with about 2 to 4 inches of snow possible Monday night into
Tuesday morning. Dobbs

.LONG TERM...valid for Tue...Wed...Thu...Fri...Sat...

Tuesday will likely be the coolest day of the week as Canadian
surface high drops into the Dakotas giving us cooler east winds.
Cannot rule out some overrunning light snow or mixed precip across
our western and central cwa with moist isentropic ascent moving
across the Pac NW. Temps will be coolest in our east of course.
Temps in our west may jump up in the afternoon if SW winds develop
off the foothills, which seems like a decent bet as current
models show pressure falls in central and southeast MT by
afternoon. Have expanded pops a bit on Tuesday, and raised temps
slightly in our west...where we could see 50 again...as opposed to
the upper 20s or lower 30s in our far east.

Warming trend in store for Wednesday and Thursday as ridge settles
in with increased downslope gradients. Should see high temps to
near 60F Wednesday then well into the 60s on Thanksgiving. We
could reach record highs (lower-mid 60s) on the 23rd, but records
for Thanksgiving Day itself will be tougher. As for precip, we
could see some brief warm frontal rain/snow develop late Tuesday
night into Wednesday, otherwise expect a dry period for the lower
elevations. We`ll also see another period of enhanced winds along
our western foothills from Tuesday night through Thursday.
Advisory speeds are possible at Livingston and Nye.

Next potential weather-maker of interest will be a weak shortwave
coming off the Pacific on Friday. Airmass looks to stay warm
enough for mainly rain showers at lower elevations. Should see a
few inches of snow for our mountains. System exits Friday night
and ridging will build back in for Saturday. Should see temps
return to closer than normal by the end of the week.JKL

&&

.AVIATION...

VFR conditions will prevail over the next 24 hours. Expect
breezy conditions across much of southern MT, especially around
KLVM and the foothills with wind gusts 40-50 kts overnight and
into Sunday. BT

&&

.PRELIMINARY POINT TEMP/POPS...

    Sun     Mon     Tue     Wed     Thu     Fri     Sat
-----------------------------------------------------------
BIL 029/051 032/049 026/042 035/060 044/063 041/053 031/043
    00/N    02/W    22/W    21/N    11/B    22/W    11/B
LVM 030/050 035/045 031/049 040/059 047/060 042/049 027/041
    00/N    04/W    23/W    21/N    11/N    23/W    21/B
HDN 022/054 028/052 024/042 030/062 037/065 038/054 028/045
    00/U    02/W    21/B    11/N    11/B    22/W    11/B
MLS 025/053 027/049 018/033 025/060 037/063 039/053 027/040
    00/U    01/N    11/B    12/W    00/B    12/W    11/B
4BQ 024/057 027/052 022/039 028/061 040/064 039/054 029/043
    00/U    01/N    21/B    01/N    00/B    12/W    21/B
BHK 021/052 025/052 011/029 018/056 034/060 036/052 025/037
    00/U    01/N    10/U    02/W    11/B    12/W    10/B
SHR 017/055 028/053 025/043 029/063 035/065 036/054 027/045
    00/U    02/W    11/B    11/B    00/B    12/W    21/B

&&

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

&&

$$
weather.gov/billings



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