textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Elevated, gusty west winds continue through tonight before calming on Saturday.

- A Winter Weather Advisory remains in effect for the Glacier Park Region and US Highway 2 through Saturday morning for snow and blowing snow.

- Mild and dry conditions prevail Sunday through Tuesday, followed by a return to active weather mid-to-late next week.

Elevated, gusty westerly winds remain the primary short-term concern, with valley gusts of 25-40 mph and ridgetop gusts of 50-70 mph continuing through tonight. These winds will gradually calm on Saturday as upper-level ridging and a split-flow pattern build in. The one exception will be Lemhi County, where a 90-knot 250mb jet streak will brush the area, maintaining breezy conditions aloft through Sunday morning.

A Winter Weather Advisory is in effect for the Glacier Park Region and US Highway 2 from Essex to Marias Pass through Saturday morning. A backdoor cold front will bank against the Continental Divide, bringing light snow. Combined with strong winds, this will create blowing snow, reduced visibility, and difficult conditions for both roadways and backcountry travel. The core of the dense, cold air mass will remain confined east of the Divide.

High pressure promotes mild, dry conditions Sunday through Tuesday. By Wednesday and Thursday, a Pacific trough moves inland. While the best moisture and dynamics track south into the Great Basin, light precipitation will return. Snow levels will start around 5,000 feet on Wednesday before dropping to 3,000-4,000 feet by Thursday. Looking ahead to the March 7-9 timeframe, global ensembles hint at a deeper, colder trough settling in. While specific details remain uncertain at this range, this pattern would be much more conducive to cooler-than-normal temperatures and widespread lower-elevation snow.

AVIATION

VFR weather conditions prevail, except for a window of MVFR ceilings and light snow at KGPI after 08Z.

Deep boundary layer mixing will drive widespread westerly surface gusts of 25-35 kts through 28/02Z, generating moderate to severe low-level mechanical turbulence and mountain wave activity across the airspace.

Between 28/02Z and 28/03Z, most valley inversions will establish and surface winds will rapidly decouple. However, a 40-50 kt westerly jet will persist at and above 2,000 ft AGL, setting up a sharp non-convective LLWS boundary overnight. KHRF is the localized exception, remaining mechanically mixed with channeled southerly gusts and no significant LLWS threat. Widespread diurnal mixing and gusty westerlies will resume by 16Z Saturday though much calmer than recent days.

MSO WATCHES/WARNINGS/ADVISORIES

MT...Winter Weather Advisory until 2 AM MST Saturday for West Glacier Region.

ID...None.