FXUS65 KMSO 122021 AFDMSO

Area Forecast Discussion National Weather Service Missoula MT 221 PM MDT Thu Sep 12 2024

DISCUSSION
A slow moving low pressure system will drift to the northeast tonight into Friday morning. A band of steady precipitation, currently located over north central Idaho, will shift into western Montana, with wrap-around moisture developing into northwest Montana near the Continental Divide. Precipitation will continue to largely be beneficial to the region with amounts of 1 to 2 inches of liquid already occurring through portions of Clearwater County and the Lower Clark Fork Region. Snow levels as low as 7500 feet have been observed and will likely result in a few inches of slushy wet snow in the highest terrain of southwest Montana, Lemhi County and along the Continental Divide into Friday morning. Those recreating in the backcountry will encounter wet, raw conditions, and potentially challenging travel on high- elevation roads.

The low pressure system will exit the region during the day on Friday, leaving cool and showery conditions in its wake.
Temperatures still look to trend warmer this weekend, approaching near normal values for this time of year of upper 60s and 70s.
However, forecast models have been trending away from high pressure ridging and show periods of showers and clouds continuing, especially across northwest Montana. Locations that do see some overnight clearing will likely see development of fog and low stratus in the morning hours.

Forecast models continue to indicate another low pressure system will cut off along the west coast, dig south into the Great Basin and then lift northward through the Northern Rockies Region Tuesday into Wednesday. There is still some difference in the exact track this low pressure system will take and thus confidence in potential precipitation amounts is still somewhat low. That being said, another round of potentially significant rainfall is possible for portions of western Montana and north central Idaho.
And we can say with high confidence (close to 100 percent) that we will not be returning to hot and dry conditions through at least mid to late next week.
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