Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 132126

Area Forecast Discussion
National Weather Service Billings MT
326 PM MDT Sun Aug 13 2017

.SHORT TERM...valid for Mon and Tue...

Weather system over British Columbia/Pacific NW still set to move
into the northern Rockies over the next 24-36 hrs. This will
transition us to a cool and rainy period to start the work week.

Associated cold front is situated out west of our CWA at this time
with plenty of shower activity being generated by large scale
height falls/vorticity. Frontal precipitation is expected to move
into our western CWA by the end of the day and spread across the
western and central zones overnight, but fade before it really
reaches our far eastern zones due to outrunning supportive
dynamics. However, secondary vorticity will move across our region
from the southwest by morning. This looks moderately potent and
should provide wetting rain to much of our zones as it moves
across Monday. There will be a low level convergent line across
the eastern zones. Bulk shear looks decent here as well to support
sustained updrafts. So a few strong storms may develop out across
our eastern zones Monday, even as early as midday. Yet another
piece of energy drives up in the south/southwest flow from Wyoming
on Tuesday morning and should be a good precipitation maker for
the southern and eastern zones.

Look for temperatures in the 70s for most locations at the lower
elevations with 50s and 60s in the high country.

A side note...we will carry a mention of smoke in the western
zones tonight as front may push some western wildfire smoke into
the area. We may extend this into Monday, but will wait to see how
it plays out. BT

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

Models appear to have come into much better agreement for the
extended forecast period, pointing toward mostly dry conditions,
with temperatures trending upward toward 90s by the weekend.

Weak zonal to slightly northwesterly flow aloft will persist
through Thursday night. There appears to be only one significant
wave crossing the region through the period that may allow for
some development. A weak wave crossing the region Wednesday
night/Thursday, could bringing a chance for showers and thunder to
mainly eastern zones. The wave appears to manifest like a dry
line at this time, due to very limited moisture availability in
the west, collecting what little moisture is available until can
build up enough to support development. Eastern zones appear to
have slightly better PWATs, and may bringing improved PoPs in that
area through the day Thursday. That said...bulk of activity could
end up east, so will have to continue to watch. Continued with
slight pops at this time, but did expand slightly further west.
Shortwave ridging aloft crosses the region Friday...with a return
to dry zonal flow by Saturday morning. AAG



VFR will prevail at the terminals today. Scattered showers
continue across southern zones...including the Bighorn mountains.
More showers and thunderstorms are expected to develop across the
plains west of Billings through this afternoon, and activity will
continue to spread eastward across the region this evening. Mountains
will be obscured at times. Localized reduction in VIS to MVFR
conditions is possible in showers. AAG


    Mon     Tue     Wed     Thu     Fri     Sat     Sun
BIL 060/075 057/077 054/083 057/083 056/087 058/089 058/090
    66/T    43/T    20/B    11/U    00/U    01/U    10/U
LVM 053/075 047/077 046/081 048/083 046/087 048/088 050/089
    57/T    43/T    20/B    10/U    00/U    00/U    00/U
HDN 059/075 056/078 052/085 055/085 055/089 056/092 056/093
    46/T    44/T    11/B    11/B    00/U    01/U    10/U
MLS 062/079 058/079 055/086 057/086 056/088 059/093 059/093
    23/T    34/T    10/U    12/T    10/U    00/U    00/U
4BQ 060/080 056/077 052/085 056/086 055/088 057/092 058/093
    23/T    45/T    11/U    12/T    10/U    00/U    00/U
BHK 054/076 055/076 051/082 055/082 053/085 054/089 056/091
    15/T    65/T    21/U    12/T    20/U    00/U    00/U
SHR 056/076 053/073 048/082 051/082 050/086 052/089 052/090
    35/T    43/T    22/T    12/T    00/U    01/U    10/U


MT...Red Flag Warning in effect until 9 PM MDT this evening FOR
      ZONE 117.


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