textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Mild weather pattern continues under southwest flow into next week.

- Periods of valley fog and low clouds (stratus), especially in western Montana.

- A weather system will bring showers, light rain or snow, and high-elevation snow on Sunday.

High pressure is re-establishing itself over the Northern Rockies today, resulting in daily fog and stratus developing each morning through Saturday. Patchy areas, especially along bodies of water, can expect dense fog. Once the fog and low clouds settle in, they will linger for several hours and be slow to clear. If widespread low clouds persist, afternoon temperatures will struggle to reach forecast highs.

The next weather system will track through the Northwest, moving along the Canadian border on Sunday. A trough will break down the ridge of high pressure, bringing showers and high-elevation snow (above 5,500 feet) along the Idaho/Montana border and in northwest Montana. Winds will also increase, with valley gusts up to 25 mph and higher elevations experiencing gusts of 30 to 40 mph. These winds will also help break up the valley inversions that develop on Friday and Saturday.

Long-range forecast models suggest high pressure will rebuild to start next week. This pattern will once again favor areas of valley fog and stratus.

AVIATION

Valley fog and low clouds have redeveloped across western Montana this morning as high pressure re-establishes itself over the Northern Rockies. The fog and low clouds will be very slow to clear this morning, as surface winds will not be strong enough to mix out the valleys. Ridge tops will likely see southwest winds between 10 and 20 knots. Daily fog and stratus will be a impact each morning through Saturday, before another weak weather system moves through Sunday to clear out the valleys.

MSO WATCHES/WARNINGS/ADVISORIES

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