Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 170849

Area Forecast Discussion
National Weather Service Billings MT
249 AM MDT Sun Sep 17 2017

.SHORT TERM...valid for Tdy and Mon...

Satellite imagery shows flat ridging over the region with high
cloud streaming in from the west in advance of weak shortwave
moving through ID. We will not see any precipitation with this
wave, but the increased cloud cover is likely having a negative
effect on fog formation across our west/central parts as of 230am.
Fog with a visibility to a quarter mile occurred briefly at Miles
City within the past hour. Though high res models do not show much
in the way of fog early this morning, the MLS ob is an indication
that we will see some localized fog especially in river valleys
across our east. This is to be expected after our recent rain
event. Will keep mention of fog this morning but have lowered
coverage to patchy, and dropped mention of fog over our western
foothills where light downslope winds have developed. Main fog
impacts will be with regard to aviation of course.

There will be some theta-e return near the MT/Dakotas border
today, which with aforementioned shortwave could allow some
convection to develop tonight a little east/southeast of our cwa.
Something to watch today.

Otherwise we will see a period of dry and warmer weather today and
Monday under a zonal flow aloft. Expect highs back to the 60s to
near 70F today, then 70s to near 80F on Monday, the latter of
which with some pre-frontal assistance. Well-mixed SW winds will
increase ahead of the front in our west, and could see gusts near
50 mph across our western foothills including at Livingston.

Surface front associated with deep Pacific trof will bring a good
chance of showers along with some frontal wind across the area
Monday night. Expect snow levels to fall to 6500-7000 feet over
our western mountains by late Monday night or early Tuesday, so
there will be snow accumulation over the high terrain. This
includes Beartooth Pass.


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

Pacific trof for all intents and purposes sits over the region
through the period, with the trof axis moving over the area toward
the end of the week. This will keep temperatures cool and chances
for precipitation going through the extended forecast period.
Latest GEFS Plumes show significant moisture potential through the
extended period and the latest GFS is hinting at precipitation
totals well over an inch over the next 7 days. With the cold trof
aloft, mountain locations will see periods of snow through the
week. The Monday night-Tuesday, and Thursday into Saturday period
look like the heaviest snow potential periods in the mountains,
and could be talking close to a foot in some of the highest
elevations during this period. This may keep Beartooth Highway
availability for travel in question. Highs look to be in the 50 to
65 degree range, with lows from 30 to 45 degrees through the
extended forecast period. In Summary, Showery and Cool look to be
the rule for the week ahead into next weekend. Chambers



Areas of fog are expected across the lower elevations this morning
and may be dense in spots from Billings to the east. Already have
visibility reported to 1/4sm in Miles City this morning. Billings
and Sheridan TAF sites could also see 1/2sm or lower visibility
at times through 15z. Fog should dissipate by 16z with VFR
conditions in place for the rest of the day and into tonight.



    Tdy Mon     Tue     Wed     Thu     Fri     Sat
BIL 068 047/076 046/055 040/063 042/055 040/053 040/058
    0/B 00/B    56/T    31/B    24/W    76/W    32/W
LVM 067 042/072 037/051 039/055 035/049 033/050 030/053
    0/N 02/T    76/T    45/T    44/W    55/W    31/B
HDN 069 042/079 045/056 038/066 041/057 038/054 038/060
    0/B 00/B    46/T    31/B    23/W    76/W    32/W
MLS 068 043/080 048/058 038/066 043/061 039/056 038/061
    0/B 00/B    35/W    31/U    22/W    55/W    32/W
4BQ 067 041/081 047/056 037/067 042/062 039/055 037/060
    0/B 00/U    35/T    41/U    22/W    54/W    22/W
BHK 065 040/080 048/058 038/066 043/064 041/057 037/060
    0/B 00/U    24/W    41/U    22/W    65/W    32/W
SHR 067 039/080 043/052 033/063 038/056 036/051 032/055
    0/B 00/U    47/T    42/W    23/W    55/W    23/W




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