Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 171652
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
952 AM MST Fri Nov 17 2017

.UPDATE...

A few minor updates made to the forecast based on current
rain/snow shower trends. The main piece of energy that brought
snow showers to the mountains, and in southern portions of the
forecast area, is quickly translating south and east out of the
region. Drier air is moving in from the northwest in it`s wake but
another piece of energy will drop southeast later this morning
into the afternoon giving the mountains another shot for snow.
Expecting accumulations to be lighter given the drier air moving
in, but can`t rule out an additional 1 to 3 inches for our
mountain locations.

Winds are still forecast to increase from the west this afternoon
and into the overnight hours as the pressure gradients tighten
across the Rocky Mountain front. Winds gusts should remain below
60 mph along the foothill locations like Livingston, Nye, and Big
Timber, but wind gusts should hit 40 to 55 mph after midnight.
Dobbs

&&

.SHORT TERM...valid for Tdy and Sat...

Upper trough was swinging across the Pacific Northwest and will
continue to advance east across the northern Rockies today. A slug
of tropical moisture was lining up on the front side of the
trough and this was streaming into the southwest mountains. As the
trough pushes east, this deep moisture source will get shunted
east and south of the area. Will keep the Winter Storm Warning
going for the Beartooth/Absarokas, with the heaviest snow early
this morning.

Latest models have pushed the best shot of precipitation over
southern sections of the forecast area. Evening crew adjusted the
morning PoPs to account for this. Adjusted PoPs back north just a
bit, as the ECMWF was still hanging on to things a little farther
north (although lower resolution does account for some of that),
also due to a band of returns on KBLX developing over the last
hour from just south of Livingston to Laurel. Instability, as
clearly evidenced on water vapor and infrared satellite loops,
will swing over the area today, so despite atmospheric moisture
depleting, will need to keep scattered PoPs going today as
instability will surely be enough to develop rain/snow showers.
Precipitation will likely be banded in nature from southwest to
northwest and contain bursts of precipitation.

Have raised PoPs and snow amounts from southern Big Horn county
southward. Kept snow amounts just below Advisory criteria in the
Bighorn mountains as the deep moisture source does sink south
through the morning, but it will be close. Sheridan will
experience snow showers that could quickly accumulate this morning
to an inch or so, but that appears to be mainly on the grassy
surfaces with road surface temperatures remaining relatively warm.
Will have to watch these areas closely though for potential
higher snow rates. Expect an inch or two of snow along the
foothills this morning and will need to keep a close eye there
too, should snow hang on longer than current models trends have it
doing.

Winds will increase this afternoon as the area dries out from
northwest to southeast. Winds should stay up tonight with a breezy
day in store for Saturday. Temperatures will be quite a bit
cooler today and Saturday compared to the very mild readings of
yesterday, some 15-20 degrees cooler. West to northwest winds will
make it feel cooler still. Winds will become strong this evening
from Livingston to Nye. Winds may approach Advisory criteria late
tonight and Saturday, but the period of strongest winds looks to
be Saturday night and Sunday. Pattern appears to be setting up for
several days of strong winds in these locations. Will issue a HWO
to advertise the potential for several days of strong winds for
the western foothills, especially from Livingston to Nye. TWH

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

Extended forecast continues to look warm, breezy, and mainly dry,
at least for the lower elevations.

Warm and continued breezy Sunday afternoon. gusty wins are
expected in favored gap flow areas around Livingston and Nye, as
lee trof builds into the region. Downsloping flow will also bring
increased winds to lower elevations. A disturbance moving east
through southern Canada will bring a cold front across the
region on Monday afternoon/evening. This will bring enhances
snow potential to the high terrain, but little chance of precip
across the lower elevations, with only a slight chance west of
Billings. Biggest impacts at this time appear to be a bit of a
cool off for Tuesday, a break from gusty winds.

Temps are expected back into the 50s Wednesday as downslope flow
returns and cool air retreats east. Some mountain snow is
possible Wednesday night into Thanksgiving, as Pacific moisture
continues continues to stream into the mountains, but do not
expect any snow into the Plains at this time. Expect to see highs
in the mid to upper 50s across the region Thanksgiving Day.

A cold front is progged to slide through the region Thursday
night, bringing potential for precip across the region. Precip
type across the plains will depend greatly timing of front, and
cool off across the region that night. Rain/ snow mix is possible
across lower elevation, before transitioning to snow. AAG

&&

.AVIATION...

Upper disturbance will bring isolated to scattered rain/snow
showers to the region today, especially along the southern
mountains and foothills. Expect occasional reductions to MVFR-IFR
at KSHR, and mountains will be frequently obscured. Expect
improvement to VFR everywhere tonight. W-NW winds will gust to
20-30 kts this afternoon and evening. Winds at KLVM will increase
to gusts 35-45 kts late tonight into early Saturday. JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Sat     Sun     Mon     Tue     Wed     Thu
-------------------------------------------------------
BIL 041 026/042 026/047 033/048 026/042 034/056 039/057
    2/W 00/N    00/B    02/W    21/B    11/B    11/B
LVM 037 023/039 025/045 032/045 028/045 038/054 042/053
    5/W 11/N    00/N    03/W    31/B    12/W    22/W
HDN 043 025/045 022/050 028/051 023/044 029/058 036/058
    3/W 00/N    00/U    01/E    11/B    11/B    11/U
MLS 044 025/043 023/049 029/048 020/037 025/054 036/056
    1/E 10/N    00/U    01/E    11/B    11/B    11/U
4BQ 042 026/043 023/051 028/052 023/041 027/055 037/059
    4/W 10/N    00/U    01/B    11/B    11/B    10/U
BHK 042 020/040 020/049 027/050 016/033 019/050 033/055
    2/W 10/N    00/U    01/B    11/B    11/B    10/B
SHR 040 021/043 020/052 025/052 024/045 028/058 034/059
    9/W 20/B    00/U    01/B    11/B    11/B    10/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Winter Storm Warning in effect until 5 PM MST this afternoon
      FOR ZONE 67.
WY...None.

&&

$$
weather.gov/billings



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