Area Forecast Discussion

KEY MESSAGES

- Areas of rain near the Canadian border late today into tonight.

- Dry Wednesday ahead of showers and thunderstorms Thursday and Friday.

- Warmer and drier by the end of the weekend.

DISCUSSION

- Meteorological Overview: A fast moving trough within a northwesterly flow aloft along the BC/Pac NW coast will slow considerably through the day today as it intensifies and eventually splits some of its energy. The weaker portion of this troughing skirts across the Canadian border this evening and tonight, which will foster some generally light rain near and north of Highway 2.

The stronger portion of the aforementioned trough becomes cutoff over northern CA/vicinity Wednesday, leading to a southwesterly flow aloft developing across the Northern Rockies. Temperatures look to trend warmer as a result of this flow aloft, but given the anticyclonic nature of the flow typical afternoon and evening shower and thunderstorm activity looks to hold off til Thursday as the core of the upper disturbance begins its approach.

Showers and thunderstorms, a few on the strong side, look to develop Thursday afternoon, initially across Southwest Montana. Uncertainty increases Thursday night into Friday with respect to the track and timing of the upper disturbance, though there will be at least some risk for another round of showers and thunderstorms by Friday afternoon.

Looking toward the weekend the upper level disturbance begins to exit eastward. A few lingering showers early Saturday morning cannot be ruled out ahead of a drying trend through the remainder of the weekend into early next week. -AM

- Forecast Confidence & Scenarios: The largest source of uncertainty is with respect to the timing and track of the upper level disturbance Thursday into Friday. A slower track, or one that keeps the Northern Rockies within a southwesterly flow aloft longer would foster a second day of showers and thunderstorms. The track of this disturbance will also play a large role in how much shear and resulting risk for organized severe weather will materialize. -AM

AVIATION

15/06Z TAF Period

Fairly quiet conditions expected overnight and through this afternoon, other than some passing clouds. An upper level disturbance will move from west to east along the US/Canadian border after 00z Wed, which will bring in some lower clouds and a chance for showers near the US/Canadian border, mostly after 00z Wed. Brusda

PRELIMINARY POINT TEMPS/POPS

TFX WATCHES / WARNINGS / ADVISORIES

None.