Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Missoula Montana
245 PM MDT Tue Oct 25 2016
Discussion... rain and stable conditions today will again lead
to the potential for patchy fog for Wednesday morning, so patchy
fog has been expanded to more valley locations in the forecast.
The next weather disturbance is still expected to produce rain
mostly north of Highway 12 on Wednesday. The rain will then linger
in northwest Montana for Thursday, while the rest of the region
stays fairly dry until Thursday afternoon or evening. By Thursday
night moisture ahead of friday's system starts leading to
Models have trended faster with the end of work week weather
system, which now is forecast to move through during the day
Friday. Additionally, central Idaho and southwest Montana now
look to be under the core of the system, where rainfall totals are
expected to be highest. Snow level remain high (above 7000 feet)
as the system passes.
After the system moves through, a short-lived ridge of high
pressure builds Saturday morning. Partial clearing of cloud cover
could make Saturday a foggy morning for valleys due to antecedent
By the end of the weekend, a large trough off the West Coast
begins to push east. This results in a switch to a westerly flow
pattern and cooler air over the northern rockies. Continued
moisture in the flow will mean more showers, likely with snow for
mountain passes. Timing for the most widespread showers is still
uncertain this far out, but the take away is lower snow level than
we have seen the last 2 weeks.
Aviation... off and on light to moderate rain showers will
continue throughout the northern rockies until around 26/0000z
this evening. All aviation sites will have a chance to see these
showers, that will temporarily reduce visibility and lower
ceilings. Patchy fog will again be present around most valleys in
western Montana and north-central Idaho tomorrow morning. Another
shortwave trough will push through the region beginning tomorrow.
The main focus of precipitation with this disturbance will be
northwest Montana through much of the day.