Visibility and air quality are actually getting worse in parts of western and southwestern Montana this afternoon. Smoke plumes are visible again on the satellite image below, but the weather today isn’t ideal for erratic fire behavior. What we have seen recently are strong winds and low relative humidities that fuel fires to grow so large in the afternoons, that smoke is able to rise so high into the atmosphere that very high and fast atmospheric winds carry it from place to place. However today, with less fire activity, the smoke is not rising to these very high levels of the atmosphere, and so it is under the control of the wind direction in the lower parts of the atmosphere. These winds are blowing more from the west than from the northwest at higher levels. Therefore, smoke in Idaho is blowing almost due east and places like Missoula and Helena are seeing smoke impacts this afternoon. Air quality in Missoula has risen to UNHEALTHY FOR SENSITIVE GROUPS and Helena is trending towards MODERATE. Air quality is generally the same in the Bitterroot, Butte, and West Yellowstone, where air is UNHEALTHY FOR SENSITIVE GROUPS to UNHEALTHY. To the northwest and along the hi-line, air quality is GOOD. To the east and southeast, air quality is mostly GOOD with some areas of MODERATE smoke.
A cold front is currently forecasted to start making its way across northern Montana this evening, which will continue through the night and into the morning across the south and southeast. Clouds are already starting to build across northern Montana right now, as the cold front is knocking on our door step. Winds will be very strong around the cold front—both in front of it and behind it—and the wind will change direction as the front passes. Throughout the day tomorrow, winds near the surface will blow mostly from the north, so any location south of an active fire is susceptible to smoke impacts. Also throughout the day, those winds that are very high up in the atmosphere will also change direction and will eventually come out of the north. This will reinforce the much cooler temperatures that we are expecting tomorrow, but it will also work to keep most of the smoke from Idaho away from our borders. This should also be true on Friday, but a ridge of high pressure will be building in to the western US. When this happens, we usually see a warming trend (which we will over the weekend), and atmospheric winds start to blow from the southwest. The weather will become more favorable for fire activity, and much of western and central Montana will be “downwind” of the fires again, so it looks likely that we have another smoky weekend in store for much of the state. By Monday into Tuesday, a weather system and cold front will trek across the state, bringing very strong winds and another round of fire danger on Monday. Behind the front and possibly for much of the rest of the week, fire activity will be less and so smoke impacts should be slightly less. |
Smoke in Idaho is blowing almost due east and places like Missoula and Helena are seeing smoke impacts this afternoon. Air quality in Missoula has risen to UNHEALTHY FOR SENSITIVE GROUPS and Helena is trending towards MODERATE. Air quality is generally the same in the Bitterroot, Butte, and West Yellowstone, where air is UNHEALTHY FOR SENSITIVE GROUPS to UNHEALTHY. To the northwest and along the hi-line, air quality is GOOD. To the east and southeast, air quality is mostly GOOD with some areas of MODERATE smoke. |