Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 222121

Area Forecast Discussion
National Weather Service Billings MT
321 PM MDT Thu Sep 22 2016

.SHORT TERM...valid for Fri and Sat...

Precipitation forecast still remains fairly complex in the short
term. Bands of showers are beginning to develop over western
Wyoming and eastern Idaho ahead of a digging upper-low. Hi-res
guidance suggests two areas of highest qpf tonight. One along the
Beartooth/Absarokas and north toward Harlowton and the second
area over the Bighorns extending northeastward to the eastern
Plains. Billings, although still expected to receive rain, may
fall in between these heaviest bands, therefore I have scaled
back qpf amounts for the Billings area tonight. Precip amounts
should range between 0.25 and 0.50 inches in most places during
the overnight hours. Moist easterly flow over the eastern Plains
should allow for areas of fog to develop, reducing visibilities
for the better part of the morning hours.

Like today, expecting coverage of showers to reduce during the
day. There will be bands of rain in the area but exact placement
is still uncertain, so most areas are carrying a 40-50 percent PoP
during the day until things become more definitive. Next wave of
rain arrives late Friday into Saturday morning as the Low pressure
system slides northeastward across the area. Model has trended
toward a stronger solution for the low and therefore more wrap
around rainfall on the back side.

Rainfall will clear from west to east Saturday afternoon as the
Low departs. Have included Billings on the westernmost edge of the
heavier rain band on the backside of the low on Saturday
afternoon. This wrap around moisture position will be critical in
determining whether Saturday afternoon in Billings will be wet
and muddy, or just cloudy and cool. If you are planning outdoor
activities this weekend, expect wet conditions and keep posted to
the latest updates.

The models have trended toward a stronger surface low over eastern
Montana on Sat afternoon which should produce gusty winds from Billings
to Roundup and eastward over the Plains. Northwest winds 30 to 40
mph will likely persist through much of the day.

Friday night into Saturday accumulating snow will cause impacts to
mountain passes in the Beartooth/Absarokas and Bighorn Mountains.
Given the amount of qpf and the proximity of the upper-low several
inches of snow is possible.

System finally clears the area Saturday night. Skies clearing
should allow low 40s to upper 30s on Sunday morning. Walsh

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

Long term period will be mostly benign as the upper level low`s
influence on our weather departs on Sunday and is replaced by
upper level ridging through next week. A weak piece of energy is
forecast by some models to split off the parent low and dive south
and strengthen over the southern US early next week. This could
give extreme eastern parts of the forecast area a chance at
showers in the middle of the week, but for now left any mention of
rain out of the forecast. As the upper level flow turns more
westerly late next week a weak disturbance could pass through the
region next Thursday, so for now just mentioned a slight chance of
rain in western zones.

As for temperatures, folks can expect the lower 60s on Sunday
with a warm up into the low 70s by Thursday of next week. Overall,
a very seasonable start to the Fall season. Dobbs


IFR/LIFR conditions will return to area terminals after 00z as
showers move into the region. These conditions should last through
at 12z with occasional relief to MVFR during the period. After
12z, expect a gradual lifting of CIGS and VIS to IFR/MVFR levels
tomorrow afternoon. Mountains will be obscured through the
overnight and daytime hours. Dobbs



    Fri     Sat     Sun     Mon     Tue     Wed     Thu
BIL 051/058 048/057 043/063 043/067 046/072 048/073 048/071
    97/T    77/W    31/B    01/U    11/U    11/U    11/B
LVM 047/054 043/055 037/061 040/067 044/071 045/073 045/072
    87/T    74/W    21/U    01/U    11/U    11/U    11/B
HDN 051/062 047/057 042/063 041/067 044/072 046/073 047/072
    84/T    78/W    31/B    11/U    11/U    11/U    11/U
MLS 053/063 049/055 042/061 040/064 043/070 047/072 048/071
    96/T    88/W    51/N    11/U    11/U    11/U    11/U
4BQ 052/069 049/055 042/060 038/064 041/069 046/074 047/074
    64/T    77/W    41/N    01/U    11/U    11/U    11/U
BHK 049/061 049/056 042/057 038/061 040/065 044/070 045/071
    67/T    76/W    52/W    11/U    11/U    11/U    11/U
SHR 051/065 046/055 041/059 040/066 041/071 044/073 046/074
    84/T    66/W    31/B    11/U    11/U    11/U    11/B




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