Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 200352
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
852 PM MST Sun Nov 19 2017

.UPDATE...

Winds have been gusting to 65 mph this evening near Livingston and
Nye as surface pressure gradients tighten. Expect the winds to
continue to increase overnight, spreading farther out onto the
foothills for places like Big Timber as winds increase aloft and
subsidence moves overhead. The High Wind warnings for the
Livingston area and Beartooth Foothills remain on track. Have gone
ahead and expanded the warning to include the Northern Sweet Grass
zone, where gusts of 55 to 65 mph are possible late tonight
through tomorrow. The strongest winds are expected to affect the
Big Timber area around sunrise. 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 Mon and Tue...

Two weather stories we want to highlight in the short term period.
The first will be very strong winds along our mountain foothills
in locations like Livingston, Nye, and Big Timber. The second will
be a cold front pushing into the region from the north that will
give much of south-central Montana a chance for rain and snow
showers.

The winds have been routinely gusting to 50 to 60 mph this
afternoon along our mountain foothills at Livingston, Nye, and
other locations along the Beartooth Front. As the sun sets we
will see these winds pick back up as the pressure gradient
strengthens across the rocky mountain front and stronger mid-
level winds move into the region. With this in mind, have upgraded
the Beartooth Foothills near Nye, and the Livingston area into a
High Wind Warning. Folks should be ready for the possibility of 75
mph winds which will bring hazardous crosswinds for semi-trucks,
high-profile vehicles, and anyone trailing items behind vehicles.
Please consider alternate routes tonight. The strongest winds
will occur from 6pm tonight to 6am Monday before an approaching
cold front from the north gradually reduces the pressure gradient
through the morning and early afternoon hours.

By Monday afternoon the cold front begins entering northern
portions of the forecast area by Roundup and Miles City. As this
front pushes south Monday evening, it will combine with moisture
moving in from the west in association with a Pacific disturbance
to produce scattered rain showers across the Plains and Mountain
snow to our west. The rain showers will turn to snow by Tuesday
morning as cold air moves in from the north. Latest trends in the
model guidance have increased the precip amounts and brought in
cooler conditions so rain/snow chances were increased and brought
additional snow accumulations into the forecast for both the
Mountains and the lower elevations. The heaviest amounts will be
over the mountains and along/east of the cold front depending how
far south and west it can make it. West of this cold front,
downslope conditions caused by the Pacific disturbance moving east
will keep a majority of the precipitation out of these areas.

Winds quickly switch back to the west on Tuesday afternoon into
Wednesday morning as the disturbance moves east. Will need to
watch these winds for possible advisory conditions as pressure
falls redevelop along the Rocky Mountain front. Dobbs

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

Wednesday and Thanksgiving Day will be much warmer than normal
with strong downslope flow under ridging aloft. Expect highs into
the 60s, with near 70F possible on turkey day, which will be the
warmer of the two days. Only possible issue is cloud cover as a
cirrus shield could hold back temps a bit. Record highs will be
challenged on the 23rd.

SW winds at Livingston and Nye could reach advisory criteria both
Wednesday and Thanksgiving Day, i.e. gusts to 60 mph possible.
With mid level winds to near 50 kts and a favorable gradient and
stability, advisory level gusts look like a good bet at this time.
A heads up for holiday travelers that strong cross winds are
likely on I-90.

Models are in good agreement with timing of a Pacific shortwave
late Thursday night and Friday. It will be brief, but there is a
decent chance of lower elevation rain showers and some mountain
snowfall. Given the increased confidence have raised pops.

Dry and cooler but certainly not cold weather in store for next
weekend in the wake of the Friday wave. Look for temps to remain
above late November normals. JKL

&&

.AVIATION...

VFR conditions will prevail through tonight and Monday morning.
However, look for some obstructions to the Absaroka/Beartooth
Mountains Monday afternoon. Main threat to aviation in our region
is the very strong surface winds from KLVM to K6S0 through
tomorrow. Winds gusting from 50 to over 60 kts is expected,
strongest between 10Z and 18Z. In addition, some LLWS is possible
around KMLS and KBHK tonight. BT

&&

.PRELIMINARY POINT TEMP/POPS...

    Mon     Tue     Wed     Thu     Fri     Sat     Sun
-----------------------------------------------------------
BIL 035/050 026/042 038/063 045/064 044/055 032/047 031/051
    03/W    42/W    21/N    00/B    03/W    00/B    11/B
LVM 035/046 030/050 042/059 048/063 044/051 029/046 031/049
    07/W    63/W    21/N    11/N    15/W    11/B    11/B
HDN 030/051 024/040 033/064 037/064 038/057 029/048 027/050
    03/W    52/W    11/N    00/B    03/W    00/B    11/B
MLS 029/050 018/031 026/061 038/065 039/054 027/045 025/046
    03/W    31/B    12/W    00/B    03/W    00/B    11/B
4BQ 030/053 022/037 031/063 040/065 040/056 029/047 026/050
    03/W    62/J    11/N    00/B    03/W    10/B    01/B
BHK 028/052 012/029 021/059 034/062 038/053 024/043 021/044
    03/W    21/U    12/W    00/B    03/W    00/B    11/B
SHR 026/054 025/045 032/063 035/067 038/056 027/049 026/052
    02/W    42/W    11/B    00/B    03/W    10/B    01/B

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...High Wind Warning in effect from 2 AM to 6 PM MST Monday FOR
      ZONE 41.
     High Wind Warning in effect until 6 PM MST Monday FOR ZONES
      65-66.
WY...None.

&&

$$
weather.gov/billings



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