textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Areas of degraded air quality from regional wildfire smoke.

- Warming trend through Friday this week.

- Elevated fire weather concerns by Friday, from hot, dry, and breezy conditions.

Satellite imagery this afternoon shows widespread smoke impacting the Northern Rockies associated with wildfire activity. This smoke has reduced visibility and has prompted to the issuance of various air quality alerts from the Idaho and Montana DEQ offices. Surface observations highlight a cold front tracking along and east of the divide. Looking ahead to this evening and overnight, a pressure gradient will strengthen along the divide, with easterly winds being felt as far west as the US-93 corridor from Kalispell through the Bitterroot Valley. The strongest winds overnight will focus over the higher terrain, with gusts of 20-25 mph.

Confidence is high for a warming trend through Friday this week. Global ensembles show a large ridge of high pressure slowly shifting eastward from the Pacific Northwest over the Northern Rockies by Thursday into Friday. A hot, dry and warm airmass will settle across the region during this time, increasing fire weather concerns. We are closely monitoring Friday for potential critical fire weather as model guidance suggests an upper level wave will move across the ridge, with increasing winds by Friday afternoon and evening. The highest probabilities (40-60%) for gusts to 30 mph or higher are focused along and east of the divide.

Looking ahead to next weekend, global ensembles and their clusters suggest the ridge of high pressure will become centered across the Four Corners region, with a dry westerly flow pattern across the Northern Rockies. This pattern suggests seasonably warm temperatures, with little to any chances for precipitation.

AVIATION

Smoke will continue to be primary impact during the next 24 hours. Surface observations point towards areas of visibility between 3-6 miles across much of the airspace, with valley areas seeing the worst conditions as inversions have been slow to erode this morning into the early afternoon. Looking ahead to this evening an easterly gradient will strengthen along the divide, helping usher in cleaner air for KGPI and KBTM. Generally speaking, the lowest visibilities associated with smoke will be found across central Idaho and along the ID/MT border tonight into Tuesday morning.

MSO WATCHES/WARNINGS/ADVISORIES

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