947 
FXUS65 KMSO 102044
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
244 PM MDT Wed Oct 10 2018

.DISCUSSION...Light mountain showers continue to dance about parts
of SW and West Central Montana this afternoon, revealing yet again
the model bias which too quickly stabilizes and dries the
atmosphere following the passage of a northerly weather system.
That being said, the atmosphere will ultimately dry this evening,
and mostly clear conditions develop overnight. This will produce 
a rather chilly Thursday morning which is presently forecast to be 
about 5-7 degrees below normal.

Contrasting today, Thursday and Friday should be pleasantly warm
and welcomely sunny. We could even reach normal *gasp* (60 
degrees) on Friday, which would be our first day at or above
normal in nearly 2 weeks! But don't get too comfortable with 
those near normal conditions. Forecast models all agree that yet 
another unseasonably cold weather system will drop south out of 
Canada and bring with it a shot of cold, wet weather across much of
western Montana and perhaps even some of Idaho. Precipitation 
will begin along the Continental Divide in far NW Montana Friday 
night, advancing south and west overnight and persisting through 
much of Saturday. The snow level will initially be near 5500-6000
feet Friday night. But quickly come crashing down to near 2500
feet in NW Montana (Kalispell/Glacier NP) and 3000-3500 feet 
across points across West Central (Missoula) and SW Montana 
(Butte). Precipitation intensity at this time appears light and
thus valley (locations below 4000 feet) accumulations of not more
than a trace are expected. However the mountainous terrain is 
again set to receive another 2 to 4 inches with some local terrain
along the Mission/Swan/Flint Creek/Anaconda Mountains seeing 4 to
7 inches. 

Given the model bias stated above, it would not be surprising if 
precipitation lingered well into Saturday night and perhaps even 
Sunday morning. This would especially be the case across SW 
Montana where models particularly struggle with the post frontal 
northerly up slope flow. 

The very cold air mass with this weekend storm system appears to 
be the coldest thus far and therefore temperatures Sunday morning 
could turn very cold. This obviously depends upon wind and 
lingering cloud cover. But the situation certainly supports 
temperatures cold enough to advertise a wide spread hard and 
potentially damaging freeze. So stay tuned to forecast updates as 
we further refine these details.

Make no mistake about it, conditions these first 10 days of
October have been decidedly below normal. However hope for an
"indian summer", if you will, could be in the making should you
believe the long range weather models. These models do show the
possibility of one more weak weather feature bushing along the
Continental Divide on Tuesday. But thereafter conditions appear to
be trending towards high pressure supportive of drier and warmer
weather. In fact, we could see conditions more normal for early 
October (mid to upper 60s) or even early late September (upper 60s
to low 70s) if this trend holds.

&&

.AVIATION...

Low clouds and high-elevation snow showers will remain over the 
Northern Rockies air space through 11/0300Z. KBTM will continue to
see periods of MVFR conditions due to low ceilings, obscured 
terrain, and snow showers. Terrain obscurations continue to be 
concentrated near the Continental Divide and across southwest 
Montana, Lemhi County Idaho (including near KSMN). Cloud cover
will gradually dissipate overnight. There is also a chance of 
MVFR ceiling redeveloping due to stratus at KBTM overnight into 
tomorrow morning.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

$$