Scientific Forecaster Discussion
fxus65 kmso 191936
Area forecast discussion
National Weather Service Missoula Montana
136 PM MDT Thu Oct 19 2017
..cooler temperatures and mountain Snow/Valley rain expected
with cold front tonight into Friday...
..more significant rain and precipitation hitting this weekend
especially in the higher terrain...
a cold front expected late tonight will result in showers, wind
shift from the northwest and falling temperatures. Highs Friday
should be 15 to 20 degrees cooler than today per latest forecast.
Snow developing in the mountains by sunrise could accumulate up
to a couple inches near I-90 Lookout Pass, Highway 12 Lolo Pass
and especially Highway 93 over Lost Trail Pass. Showers
continuing Friday are then expected to decrease ahead of a more
significant jet stream punching into the Pacific northwest.
The timing of the weekend weather system from computer model runs
has been pretty consistent for rain and stronger wind to develop
first in Idaho late Saturday afternoon, then spread farther east
by Sunday morning. Snow levels will be somewhat higher around 6000
feet this weekend with rain amounts in the terrain below this
level in the 1 to 3 inch range resulting in local mud and rock
slides. Broader valleys like the Flathead and Missoula/bitteroot
should be shadowed due to the strong west wind with half inch to
1 inch rain. The winds in the higher terrain will also increase
the chance of falling trees in recent burn areas. After Monday it
looks generally drier, though a weather system midweek moving into
the plains may brush northwest Montana. /Ss
Aviation...late tonight into Friday, a moist cold front will
bring a west to east progression of lower ceilings and reduced
visibilities associated with rain and mountain snow above 5,000
feet. Wind shift from southerly to more northerly is expected
with the front.