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FXUS65 KBYZ 261032

Area Forecast Discussion
National Weather Service Billings MT 
432 AM MDT Tue Sep 26 2017

.SHORT TERM...valid for Tdy and Wed...

A few days of pleasant mild weather ahead as high pressure gains
the upper hand over our region. After some morning fog in the
eastern zones, there is just a slight chance of some convective 
activity over the high country today thanks to a period of 
unstable NW flow. Otherwise, we will see fair skies and milder 
temps. More sun expected Wednesday as ridging increases. 
Temperatures will be well into the 60s with a few lower 70s 
likely. BT

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

Upper ridge dominates our weather Thursday into Saturday morning
with dry and mild weather. High temperatures are expected to be in
the upper 60s to lower 70s Thursday through Saturday. This upper
ridge will be sliding eastward during this time so that it should
be exiting MT Friday night. A weak shortwave is then progged to 
track northward Friday night, which could produce an isolated 
shower over the Bighorn Mountains.

An upper low tracking eastward over the Pacific Northwest should
bring scattered showers and thunderstorms to our southwest 
mountains Saturday morning, western areas Saturday afternoon, and 
to our whole CWA Saturday night. Showers are still possible during
the day on Sunday with the upper low over central MT, which is a 
change from last night's model runs. A surface cold front should 
also move through the region Saturday night, bringing in cooler 
air for Sunday through early next week, with high temperatures
generally in the 50s across the lower elevations. The air will be
cool enough to change rain to accumulating snow in the mountains 
beginning Saturday night.

Surface and mid-level pressure gradients behind the cold front 
appear favorable for breezy conditions for much of the area 
Saturday night through early next week. In addition, gap flow 
winds near Livingston are possible beginning Sunday afternoon and 
then continuing into early next week.

For Monday, models diverge with the GFS moving the upper low more
slowly and thus keeping showers possible and the ECMWF moving the
low more quickly, giving a mostly dry day. Given the model 
uncertainty kept chance PoPs going on Monday. RMS


Patchy fog is possible this morning over eastern MT and north
central WY. A few showers are possible over the mountains this
afternoon. Mountains will be obscured at times today. Otherwise,
VFR will prevail. RMS


    Tdy Wed     Thu     Fri     Sat     Sun     Mon     
BIL 065 043/069 044/070 046/071 047/070 045/058 041/057
    0/B 00/U    00/U    00/U    01/B    33/W    22/W
LVM 062 037/067 036/068 038/071 043/066 039/053 037/052
    1/B 10/U    00/U    00/U    02/T    42/W    23/W
HDN 066 041/071 042/073 045/073 045/073 045/061 041/059
    0/B 00/U    00/U    00/U    01/U    33/W    12/W
MLS 065 042/071 045/073 046/073 049/073 048/061 042/058
    0/F 00/U    00/U    00/U    11/U    33/W    12/W
4BQ 064 041/069 042/072 045/071 047/073 046/060 040/057
    0/U 00/U    00/U    01/N    11/U    33/W    11/N
BHK 062 040/070 043/071 045/071 047/073 046/062 041/058
    1/B 00/U    00/U    00/N    11/U    32/W    11/N
SHR 062 038/067 039/068 042/069 042/070 042/057 037/056
    0/B 00/U    00/U    00/B    00/U    23/W    11/B



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