Northwest Montana Regional Forecast

Includes Lincoln and Sanders Counties ( Libby, Troy, Eureka, Yaak, Bull Lake, Noxon, Heron, Trout Creek, Thompson Falls, and The Cabinet Mountains)

Issued Monday August 19, 2019 - 7:55 p.m.

Monday night…Fair skies. Lows in the lower 40s to lower 50s with upper 50s on slopes, ridge tops and around 5000 feet. Light wind.

Tuesday…Mostly sunny and hot. Highs in the mid 80s to mid 90s with lower 70s around 5000 feet. Afternoon southwest wind 5 to 10 mph.

Tuesday night…Fair skies except for occasional high clouds. Lows in the mid 40s to mid 50s with upper 50s on slopes, ridge tops and around 5000 feet. Light wind.

Wednesday…Mostly sunny in the morning. Increasing clouds and locally breezy in the afternoon. Highs in the 80s to lower 90s with upper 60s around 5000 feet. Afternoon southwest wind 5 to 15 mph with gusts to 20 mph. Ridge top winds southwest 10 to 20 mph with gusts to 30 mph.

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Extended Outlook (Thursday through Monday)

Thursday…Cooler with a slight chance of early morning showers. Lows in the upper 40s to mid 50s with mid 40s around 5000 feet. Highs in the 70s to near 80 with mid 50s around 5000 feet.

Friday through Monday…Dry with seasonal temperatures. Lows in the upper 30s to near 50 with near 50 around 5000 feet. Highs in the mid 70s to mid 80s with near 60 around 5000 feet.

In-Depth Weather Discussion for Northwest Montana/Rockies

Issued 08/19/2019 8:10 p.m.

Short term (Monday night through Wednesday):

Temperatures warmed close to average for mid August across Lincoln and Sanders Counties give or take a degree on Monday with an abundance of sunshine. Expect Tuesday to be the warmest day of this week as an upper level ridge amplifies northward across our region ahead of a rather strong (for August) upper level trough in the Eastern Pacific. Some high cloudiness will drift across the region at times on Tuesday but the cloud cover will likely not be enough to take any edge off of the hot temperatures on Tuesday with mid 90s likely in the typical hotter locations in the valleys such as Troy, Libby and Thompson Falls with upper 80s to lower 90s elsewhere across valley locations. High elevations will also see very warm temperatures up into the lower 70s around 5000 feet. These readings will be close to 10 degrees above average for mid August. Occasional high cloudiness will stream across the region on Tuesday night which will help hold temperatures up overnight and make for a rather warm start to the day on Wednesday. Speaking of Wednesday the upper level trough will begin to approach the Washington coast and spread increasing cloud cover across our area especially in the afternoon which may help to knock down high temperatures some on Wednesday but still likely be above mid August averages. This system lacks strong dynamics and lift but will contain an impressive amount of available moisture content so the prospects for some light measurable rainfall are fairly good for Wednesday night especially for the upslope regions of the Cabinet and Coeur d’Alene Mountains and the Bull River/Clark Fork River drainages.

Long term (Wednesday night through Monday):

Strong and sharp upper level trough will pass through the region Wednesday night with at least scattered showers across much of the region with the most widespread shower activity being focused for those locations along and west of the Cabinet Mountains where some areas may pick up a tenth of an inch or so of rainfall while most other locations will only see a couple of hundreths of an inch. Cooler temperatures will follow on Thursday with seasonal temperatures persisting through the remainder of the week into the weekend and the start of the next week. A shortwave will skirt by on Saturday in the fast flow aloft and may produce one or two showers near the Canadian border but for now have left out the chances of precipitation at this time. The bigger story will likely be the pockets of frost that may develop across colder valleys Friday morning and other select mornings when skies clear and winds are light. It is going to be late August by the weekend and into next week so the chances for frost are increasing with the longer nights and dry air.