textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Warming and drying trend through Tuesday, reaching into the upper 70s to 80s for most valleys by Tuesday.

- Showers and isolated thunderstorms possible Tuesday evening, with potential for gusty winds, especially in north central Idaho.

- Widespread rain and much cooler temperatures arrive Wednesday through Friday.

Get ready for a massive weather swing this week, starting with unseasonably warm temperatures before a dramatic cool down. Today and Monday will kick off a significant warming trend, with valley temperatures peaking in the 70s and 80s by Tuesday. This is about 25 degrees warmer than average and will likely break a few local daily records. By late Tuesday afternoon and evening, we expect thunderstorms with lightning and gusty winds to develop, primarily across north-central Idaho including over the Camas Prairie. Meanwhile, southwest Montana will face elevated fire danger through Tuesday evening due to a combination of very dry air and gusty winds.

The warm weather will end abruptly Tuesday night into Wednesday as a cold front sweeps through the region. We are highly confident that this will bring much cooler temperatures, breezy conditions, and widespread rain and snow. In fact, temperatures will be as much as 30 to 40 degrees cooler by Friday! Expect moderate to heavy rain from Wednesday through Thursday, particularly over the Clearwater Mountains and the Continental Divide, where over an inch of rain is likely. There is a small chance (10 to 20 percent) that an even heavier surge of moisture could drop two to three inches of rain and snow water equivalent (SWE) along the Divide. Rising water levels in local rivers and streams is anticipated, though widespread flooding isn't expected right now. Please stay alert for water ponding on roadways and the potential for small rockslides or debris flows in steep areas.

As temperatures continue to drop, the chance for snow will increase by Thursday for higher valleys and mountain passes along the Continental Divide and in southwest Montana, including Butte, Homestake and MacDonald passes. If you are traveling through these areas, be prepared for potential winter driving conditions, though exact travel impacts will depend on the storm's final path. Looking ahead to the weekend, the weather will remain unusually cool and showery. There is also a slight chance (about 20 percent) that a second blast of cold Canadian air could sweep in over the weekend, potentially bringing snow all the way down to the valley floors in western Montana.

AVIATION

VFR weather conditions are anticipated through the forecast period with generally light and terrain driven winds.

MSO WATCHES/WARNINGS/ADVISORIES

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