Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 201522

Area Forecast Discussion...Updated
National Weather Service Billings MT
922 AM MDT Sun Aug 20 2017


A few lingering showers should gradually dissipate through the
morning across eastern areas. Otherwise, we can expect a dry day
across much of southern Montana, before shower and thunderstorm
chances increase late today into tonight across our eastern areas
as moisture and instability combine with a developing low level
jet. Have adjusted sky cover and winds to current trends, as well
as removed any mention of smoke in the forecast for today. North
to northeast winds have pushed the higher concentrations of smoke
near the surface out of our area and improved air quality. This
will be short-lived however, as models indicate smoke
concentrations increasing once again later tonight. 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 Tdy and Mon...

Quiet weather pattern for most areas across our forecast area for
the next couple of days. A westerly flow aloft today will help to
continue to mix down smoke from western wildfires so areas of
smoke have been added to the forecast for areas along and west of
a Hysham to Sheridan line. A weak disturbance moving across
northern Wyoming has resulted in showers and thunderstorms to
develop early this morning across southern Carter County and
northeast Wyoming/northwest South Dakota. These should move out of
the area around or shortly after daybreak. Otherwise, outside of
areas of smoke today, skies are expected to be partly sunny with
afternoon highs mainly in the lower to middle 80s.

Models continue to show a low-level jet developing late tonight
across western South Dakota into southeast Montana bringing a
chance for elevated nocturnal thunderstorms to those areas. As a
result, will keep shower/thunderstorm chances across Custer,
Fallon, Powder River and Carter counties tonight, with the highest
chances along the Dakota borders.

High pressure ridging builds across the Pacific Northwest Monday
as an upper low will be over east central Canada. This will result
in the upper level flow switching from westerly to northwest.
This may help shift some of the smoke to the southwest but some
areas of smoke will still be possible from mainly Billings
westward. Afternoon highs on Monday will be very similar to today
or just a degree or two warmer, although smoke may hinder the
temperatures just a bit both today and Monday. Hooley

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

Long range progs continue to be in good agreement with regard to
the overall weather pattern. Tuesday through Wednesday looks quiet
and seasonably warm as high pressure dominates the region. A
strong upper trough over British Columbia will then track east
across Canada Thursday and Friday with height falls inducing lift
over the northern Rockies while associated circulations bring in
some monsoonal moisture. While the bulk of the forcing remains
well north of our CWA, there are some short waves rounding the
bottom of the trough which may affect our area. We will continue
to keep PoP`s relatively low for now as forcing and low level
convergence is questionable. Look for western and central zones to
see the best chance of precipitation by late Thursday, gradually
shifting to the central and eastern zones by Friday evening. A
strong ridge is then suggested by both the GFS and EC for next
weekend which means mainly dry and warm conditions. BT



VFR conditions will prevail today. No aviation hazards expected.



    Tdy Mon     Tue     Wed     Thu     Fri     Sat
BIL 085 057/086 055/089 059/092 062/088 060/084 057/085
    0/U 10/K    00/U    00/U    01/B    22/T    20/U
LVM 083 046/086 046/091 050/093 053/088 051/084 047/085
    0/U 00/K    00/U    00/U    12/T    32/T    10/U
HDN 087 056/086 053/091 054/094 057/090 057/086 053/087
    0/U 11/K    00/U    00/U    01/B    12/T    30/U
MLS 086 057/086 055/089 058/093 062/091 062/087 056/085
    2/T 21/B    00/U    00/U    01/U    12/W    10/U
4BQ 086 057/085 053/089 055/091 058/090 059/087 056/086
    1/U 21/B    00/U    00/U    01/B    22/T    20/U
BHK 081 055/083 048/085 052/088 055/087 057/085 054/082
    2/T 31/B    00/U    00/U    00/U    22/T    10/U
SHR 086 053/086 050/089 053/091 055/087 054/084 050/085
    0/U 10/K    00/U    00/U    12/T    12/T    30/U




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