textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Through Tuesday: A slow moving weather system will bring prolonged, light to moderate rainfall focused along the Continental Divide and in the Glacier Park region.

- River, stream, and creek rises from widespread rain and snow melt will lead to the risk of minor flooding across northwest Montana.

- Active weather through the week into next week.

The low pressure system will continue to wrap gulf moisture into northwest Montana this afternoon into Tuesday morning. Many areas across northwest Montana particularly east of Highway 93 should expect an additional 0.25 to 1 inch of rainfall by Tuesday afternoon with the higher terrain along the Divide getting up to 2 inches. Snow levels will remain hovering around 7000 feet during this period. An Areal Flood Warning will remain in effect for the Flathead and Mission valleys until tomorrow for the flooding and ponding of water along the western slopes of the Mission and Swan mountain ranges. An Areal Flood Watch remains for the Glacier NP region for the potential of small stream flooding and rock/mud slides. A Flood Watch remains in effect for the Clark Fork river above Missoula as water from upstream makes its way through the region.

The Northern Rockies will experience a minor break in the precipitation along with some warming late Tuesday into Wednesday. Then a quick moving disturbance will push through the region on Thursday bringing widespread showers and the potential for a few thunderstorms.

Another break in the precipitation is expected for Friday. Then on the weekend a more significant low pressure system makes its way into the Pacific Northwest. The models diverge on how this low pressure system will move across the region Sunday into Monday. The latest guidance is leaning towards the low stretching and splitting into two system with the bulk of the energy going into Canada and a weak feature moving into California. The general consensus is for the Northern Rockies to remain in an active weather pattern this weekend into next week.

AVIATION

Low pressure east of the Continental Divide is sending moisture west into the Northern Rockies airspace today. The moisture feed is primarily affecting terminals along and north of about I-90 including KMSO. Expect rain to continue at KGPI and KMSO today, while migrating south to KHRF and KBTM later today and overnight while winds region-wide stay northwest or northerly on the backside of the departing low. Decreased visibility and ceiling will drop flight categories to MVFR at times due to rain and mist through Tuesday. Expect terrain to be obscured across all northwest Montana mountain ranges, especially along the Continental Divide.

MSO WATCHES/WARNINGS/ADVISORIES

MT...Flood Warning through Tuesday morning for Flathead and Mission valley. Flood Watch through Tuesday morning for West Glacier Region.

ID...None.