After a brief break from the wildfire smoke in the western valleys, the smoke settled back in last night and air quality is poor again. Cumulative particulate concentrations are HAZARDOUS in Hamilton and the Bitterroot Valley, and hourly concentrations are UNHEALTHY. Cumulative concentrations in Missoula, Frenchtown, and Seeley Lake are UNHEALTHY, but hourly concentrations are UNHEALTHY FOR SENSITIVE GROUPS and MODERATE, with an upward trend. Cumulative concentrations in the Flathead Valley are UNHEALTHY FOR SENSITIVE GROUPS, but hourly concentrations are GOOD. Other locations have had enough GOOD observations that we can say that the air quality is GOOD in Helena, Butte, Bozeman, West Yellowstone, Dillon, and most of eastern Montana.
The presence of clouds and the changing locations of smoke impacts are from a low pressure system that is making its way through parts of the western US. For the last week, we have been under a large, stable ridge of high pressure, and we saw mostly calm winds, clear skies, and heavy smoke because of it. That ridge is still over us, but this low pressure system is slowly cutting its way through the ridge. This morning, it is near the Oregon/Idaho/Nevada border. Its proximity to western Montana will continue to have an effect on our winds, which in turns affects our smoke impacts. Atmospheric winds are fairly variable in direction over western Montana, and will change throughout the day. In general, winds should generally blow from the east and southeast this afternoon, so smoke impacts will remain heaviest west of the Divide.
There will be another update this afternoon with the latest wildfire activity, smoke conditions, and a full forecast. |
Please see "Today's Report and Forecast" (left). There will be another update this afternoon with the latest wildfire activity, smoke conditions, and a full forecast. |