For the latest graphs of particulate date from Yosemite Valley click here.
Fore the latest graphs of particulate data from other Central Sierra sites click here.
Figure 1: NOAA Hazard Mapping System showing smoke plumes at the end of the day on Sept. 14th. The 350-acre Courtney Fire near Bass Lake is sending smoke across the Meadow Fire. Another new fire near Coulterville was stopped without any major smoke production. The King Fire in the American River Canyon is sending dense smoke over Lake Tahoe and Reno.
Yesterday Morning smoke in the Merced River Canyon was lifted out around 10-11am in most places. This lingering nighttime diurnal smoke caused light general haze near the Merced River Canyon. Yosemite Valley was in the Moderate AQI range for both the 3- and 24-hr. rolling averages all day yesterday. Devil’s Postpile and Tuolumne Meadows were in the Moderate Range for the 24-hr. PM2.5 average yesterday, reflecting lingering haze along the Sierra Crest. All other stations were in the Good AQI range for both 3- and 24-hr. averages.
Today Increasing transport winds and scattered clouds helped scour smoke from the Merced River drainage today, and decreasing fuel consumption continued to improved visibility in Yosemite Valley. All nearby particulate monitoring sites began the day in the Good AQI range for 3-hr. average PM 2.5 concentrations and remained there all day (no data from Oakhurst), except for Yosemite Valley, which was briefly in the Moderate AQI range right after midnight. The 24-hr. average concentrations in Yosemite Valley stayed in the Moderate range all day.
Tomorrow Smoke transport will be similar to today, however 24- and 3-hr. PM 2.5 concentrations are forecasted to improve, so long as suppression efforts are successful. Firefighters continue to face increasing winds, but humidity recovery and daytime low RH are increasing with the increasing onshore flow. The 3-hr. rolling average PM2.5 concentrations in nearby communities should remain in the Good 24-hr AQI range throughout the day, unless they are impacted by new nearby fires. Tuolumne Meadows and Devils Postpile, as well as Lee Vining, will all be impacted by smoke from the fire outside of Oakhurst, which is sending a plume over the Sierra Crest and Mono Lake.
Table 1: Observed and forecast 24- and 3-hour rolling average Air Quality Index (AQI) values for Sept.14th (observed), Sept 15th (forecast) for communities with air quality monitors. Oakhurst BAM is not reporting, but there is a strong likelihood Oakhurst will be impacted by the Courtney Fire tomorrow.
Table 2: PM2.5 1-hr. (point data) and 24-hr rolling average (line) plotted along with daily acres burned on the Meadow Fire.