textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Cool mornings and pleasant afternoons the rest of the week.

- Gusty winds and choppy lakes on Saturday, especially across northwest MT.

- Pattern shift early next week, gradually cooling and a chance of showers.

High pressure will bring mostly sunny skies and pleasant mid-October weather across the region through Friday, aside from some patchy morning valley fog. High temperatures on Friday may be slightly cooler in the valleys than some forecast models suggest due to stable conditions and stubborn nighttime inversions.

The pattern shifts on Saturday as a dry cold front sweeps through western Montana and north-central Idaho by the evening. Ahead of the front, breezy westerly winds will help warm daytime temperatures. Expect surface wind gusts of 30 to 40 mph, with exposed higher terrain seeing gusts near 50 mph. These winds will create choppy conditions on local lakes and pose hazards for small watercraft. While a few light showers may clip northwest Montana, precipitation will be negligible. Cooler air arrives Sunday behind the front, though temperatures will still remain slightly above normal for this time of year.

By early next week, a broader weather system will move into the western US, bringing a shift toward a more active pattern. While the most significant moisture and storm energy are expected to track well south of our area into the Great Basin, the Northern Rockies will still transition to a more unsettled regime. Expect a return of precipitation chances and a cool down to near-average seasonal temperatures.

AVIATION

Upper-level ridging will build over the region through Friday, generally favoring VFR conditions. However, a cooler Canadian air mass accompanied by a 1042 millibar surface high, will build into central Montana today. This will establish a moderate easterly wind gradient across north- central Idaho and western Montana lasting from 1200z Thursday through 1400z Friday. Expect breezy easterly winds up to 20 knots in the gaps and channels extending westward from the Continental Divide. This gradient will largely keep fog at bay for most airfields, though some localized fog will be possible near river bottoms. High resolution forecast soundings suggest that KBTM may be decoupled and moist enough for fog development to form by daybreak this morning.

MSO WATCHES/WARNINGS/ADVISORIES

MT...None. ID...None.