Area Forecast Discussion

FXUS65 KBYZ 200226
Area Forecast Discussion...Updated
National Weather Service Billings MT 
826 PM MDT Mon Mar 19 2018
Weak isolated to scattered shower activity has continued over the
southern mountains and foothills and northern portions of the area
this evening. Shower activity will gradually shift east overnight
as a PV axis slides through the region. Showers may be moderate to
heavy very briefly late tonight from Miles City to Baker, although
accumulations are only expected to be an inch or less. Have
updated pops and wind to current trends. Otherwise, the rest of
the forecast remains on track and the previous forecast discussion
is below. STP
.SHORT TERM...valid for Tue and Wed...
Shortwave currently in north central MT is moving slowly east.
Weak forcing and diurnal instability are allowing some shower
activity to develop over the past couple hours. Isolated to
scattered rain/snow showers can be expected mainly in west/central
parts this evening, then to the east overnight into early Friday
morning. PV axis w/ showalters near 0C will brush our far
northeast between 09-15z, with instability through dendritic
layer, so could be some briefly moderate to heavy snow showers 
from Miles City to Baker before the shortwave exits to the east.
Mainly quiet weather is in store Tuesday and Wednesday as upper
level ridge builds over the region. Temperatures will turn warmer,
with 40s to mid 50s by midweek. It will be warmest along the
western foothills where snow cover is somewhat spotty. Today's
satellite imagery shows nothing but snow cover east of Billings,
and this will have its usual cooling effect on what would be 
otherwise milder days. Western mountains will pick up some light 
warm frontal rain/snow Wednesday.
.LONG TERM...valid for Thu...Fri...Sat...Sun...Mon...
Ridge axis shifts east on Thursday, resulting in what should be
the warmest day of the week but also allowing for a moisture surge
through the great basin to begin affecting our western mountains.
Surface winds will strengthen out of the east, and this will
impact temperatures due to the abundant remaining snow cover east
of Billings. So, warmest temps should be along our western
foothills, near 60 degrees, with 40s to lower 50s further east.
Precip over our mountains will begin with high snow levels per
700mb temps rising near or a bit above 0C. Snow levels will fall
with the cold advection Thursday night and Friday. Passage of
shortwave will bring a good chance of showers to lower elevations
Thursday night into early Friday. Mixed precip and even some
freezing rain cannot be ruled out in our east with pockets of
below freezing air in valleys. Something to watch.
Active weather in store Friday through the weekend as Pacific 
trof moves through the northern Rockies over time. This will bring
at least a chance of showers each day, with periods of snow over 
the mountains, though models diverge greatly in details. Cannot 
rule out some lower elevation snow Saturday night through Sunday. 
Temps will fall back below normal. Should see drying by Monday.
Patchy fog with local IFR or lower conditions could impact areas 
from KMLS to KBHK tonight. Fog will dissipate early Tuesday with 
the passage of a weak cold front and wind shift. Otherwise, an 
upper disturbance will bring widely scattered rain/snow showers to
the area tonight...mainly in the west this evening, spreading 
east overnight. Local MVFR/IFR is possible in any heavier showers,
along with wind gusts of 20-25 kts. Mountains will be frequently 
obscured. VFR will prevail Tuesday late morning and afternoon. 
    Tue     Wed     Thu     Fri     Sat     Sun     Mon     
BIL 028/047 028/049 031/051 036/048 029/046 026/042 024/044
    10/U    00/B    01/B    22/W    23/R    42/O    21/B
LVM 027/048 028/053 033/060 035/052 028/046 023/041 022/043
    20/N    12/W    24/W    32/W    24/R    42/S    21/B
HDN 024/048 024/051 027/053 031/048 025/046 022/043 020/044
    20/U    00/U    01/B    22/W    23/O    42/O    21/B
MLS 023/038 019/041 024/042 030/041 025/041 022/037 018/039
    52/J    00/U    00/B    32/W    23/S    42/S    21/B
4BQ 021/043 020/048 026/049 033/048 026/046 023/040 020/042
    21/B    00/U    00/B    22/W    22/O    52/S    21/B
BHK 020/035 017/040 023/043 031/041 025/041 022/036 017/037
    66/J    00/U    00/B    53/W    22/S    53/S    21/B
SHR 023/046 023/050 027/055 035/051 027/048 023/042 021/043
    20/U    00/U    01/B    24/W    23/R    42/O    21/B