textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Dry and warm weather this week, with above normal temperatures.

- Showers and isolated thunderstorms across Flathead and Lincoln Counties this afternoon and evening.

Numerous showers and thunderstorms developed across northwest Montana overnight through the early morning today, with a handful of observing sites, including West Glacier recording 0.25 inches or more of precipitation. This activity was driven by an upper level trough passage within northwest flow. High-resolution models suggest shower activity will continue on the backside of this trough through mid-morning across northwest Montana. A west-northwest gradient will lead widespread breezy winds this afternoon, with gusts reaching 15-30 mph across valley areas (highest gusts south of I-90). The atmosphere will destabilize this afternoon, with scattered showers and isolated thunderstorms redeveloping across Flathead and Lincoln Counties.

Model guidance remains in strong agreement for a broad ridge of high pressure to amplify across the Northern Rockies Friday into the weekend. This will bring noticeable warming trend, especially by Sunday under a southwest flow aloft.

Looking ahead to early next week, confidence is medium-high (80% probability) for warm and dry conditions to continue with high pressure remaining over the Northern Rockies. A minority of global ensembles (20% of members) suggest a breakdown of the ridge with a quick moving Pacific system bringing a return of showers and thunderstorms during the Monday-Tuesday timeframe.

AVIATION

Rain showers will continue across northwest Montana this morning through at least 07/1400Z as an upper level trough passes within northwest flow. Terrain obscurations will be common, especially along the divide, where shower activity will focus this morning. A west-northwest gradient will set up across the Northern Rockies airspace by late morning through the afternoon, with area terminals seeing gusts of 15-25kt. High- resolution models and forecast soundings suggest the atmosphere will destabilize by 07/1900Z, with scattered showers developing across northwest Montana. The threat for lightning will focus along the divide, with lightning probabilities peaking at 20-30% across Flathead County, including KGPI by 08/0000Z.

MSO WATCHES/WARNINGS/ADVISORIES

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