Wednesday, September 11, 2013

9/11/2013 Rim Fire Extended Air Quality Report

As air quality impacts from the Rim Fire diminish over the next several days this report and the morning Air Quality Report will be replaced with a less formal informational update, produced as needed if air quality impacts are forecast.

Rim Fire, Air Quality Resource Advisor Report                        Patriot Day, September 11, 2013
 Prepared by: Ryan Bauer, Leland Tarnay, and Sharon Grant
Key Points:
  • The fire size is currently 255,146 acres and is 80% contained.  About 700 acres of growth occurred yesterday. Approximately 400 acres of those acres burned in green islands within the fire perimeter. Roughly 4,600 acres of green islands remain within the perimeter. Approximately 300 acres of new growth occurred on the eastern portion of the fire.
  • Temperature and humidity moderate slightly today before hot and dry conditions return this weekend. Instability remains high along with the potential for spotting. A chance for more thunderstorms over the Sierra crest remains today. Slope and drainage winds will be fairly light except where they align with west facing drainages in the afternoon. Weaker easterly winds will return tonight, but increase over the weekend.
·         The fire will continue to spread interior of containment lines in the Clavey River
drainage, and the Reynolds Creek and Jawbone Creek drainages in the north and northeast
areas of the fire. Fire will also spread interior of containment lines west of Harden Lake and
Harden Road, and west of Tioga Road in the east and southeast areas of the fire. Modest
spread to the northeast into the Yosemite Wilderness north of Hetch Hetchy reservoir is
expected. All Divisions continue mop-up, patrol, and suppression damage repair.

Figure 1 Rim fire operations map for 9/11/2013 showing MODIS satellite heat detections for the past 6 hours from 09:30, 9/11/2013.

Figure 2 Rim fire burned area as of 23:22, 9/11/2013 showing areas of potential continued interior burning (red) with yesterday’s fire activity (green).

Interior burning continues to clean up islands of remaining unburned fuel. This progression is shown in figure 2, above. Yesterday, another 400-500 acres burned within the fire perimeter, leaving approximately 4,600 acres of remaining islands to produce emissions over the next several days (Figure 2). An additional 300 acres of growth occurred within the timber stringers east of the fire that terminate in the rocky peaks of the Yosemite Wilderness. About the same amount of growth is possible in this area over the next two days.

Satellite imagery from this morning showed the fire area mostly obscured by clouds. Some smoke was visible in the Tuolumne River Drainage, suggesting morning impacts similar to yesterday. Only two stations, Tuolumne City and Drew Meadow ICP, reported particulate concentrations above the moderate AQI range this morning, and all areas saw better air quality than past mornings (Figure 3). Due to a significant reduction in acres burned and some favorable smoke mixing yesterday from thunderstorm activity along the Sierra crest, impacts are generally lighter and more localized.

Figure 3 3-hour average fine particulate (PM 2.5) concentration at five (5) monitoring locations near the Rim fire with associated Air Quality Index (AQI) health hazard ranges and adjectives. All data are preliminary and have not undergone quality assurance review.
Air quality monitoring continues at the two incident base camps. Smoke impacts continue at about the same time each day. Due to their topographical position relative to the fire, impacts are expected to continue until smoke production is significantly reduced (Figure 4).

Figure 4 3-hour average fine particulate (PM 2.5) concentration in the Drew Meadow and Tuolumne City Incident Base Camps with associated AQI ranges and adjectives. All data are preliminary and have not undergone quality assurance review.
Air quality within Yosemite National Park has improved considerably. Currently impacts are primarily visual in nature although conditions are expected to deteriorate into the weekend with possible negative impacts to air quality in the park. The new air quality monitors in the park are now operating properly.
Figure 5 air quality monitoring sites in the Rim Fire area with Rim fire infrared perimeter from 9/3/2013.

Table 1 selected air quality monitor data and corresponding AQI rating, meanings, and recommendations with forecast levels for today. Data are preliminary and have not undergone quality assurance review.
Follow the links in the following table to view real-time air quality monitoring data for each site.

24-hour Avg PM2.5
3-hour Max PM2.5
Level of Health Concern


Actions to Protect Yourself
For Wed.
Sept 11, 2013
Yesterday, Sept. 10
Bear Valley
S. Lk. Tahoe Carson City Minden
Air quality is satisfactory and poses little or no health risk
Bear Valley
S. Lk. Tahoe
Mariposa Greeley Hill
La Grange
El Portal
Yosemite Vly Groveland Tuol. Mdws
Air quality is acceptable for most. There may be moderate health concern for a small number of sensitive people.
Unusually sensitive people should consider reducing prolonged or heavy outdoor exertion.
La Grange
Yosemite Vly
Tuol. City



Unhealthy for Sensitive Groups
Members of sensitive groups may experience health effects.  The general public is not likely to be affected.
People with heart or lung disease, children and older adults should reduce prolonged or heavy outdoor exertion.  Everyone else should limit prolonged or heavy exertion.
Tuol. City


Drew Mdw ICP


Everyone may begin to experience more serious health effects.
The following groups should avoid all physical outdoor activity: People with heart or lung disease, children and older adults.  Everyone else should avoid prolonged or heavy exertion.

Air Quality Index (AQI) ratings are derived based on the recommendations found in Wildfire Smoke: A Guide for Public Health Officials.
Wednesday, September 11, 2013
Light downslope winds overnight carried less smoke than on recent mornings down the Clavey and Tuolumne River Drainages. Smoke impacts in the communities usually affected by morning inversions were lighter today, with Pinecrest, Columbia, Groveland, Greeley Hill, La Grange, El Portal, and Mariposa all in the good to moderate AQI ranges. Light smoke will linger in the Yosemite Valley and foothill communities for most of the day. Transport winds will remain light through the day. Diurnal upslope/upcanyon flows will be the dominant winds. A slightly better chance of thunderstorms over the Sierras today could again help smoke mix into the upper atmosphere, improving air quality conditions at the surface. Easterly winds will remain fairly weak tonight bringing nighttime and early morning impacts tomorrow similar to this morning for the Yosemite and San Joaquin Valley foothill region (Figure 6).

Figure 6 2km BlueSky particle model prediction for 07:00, 9/12/2013 showing air quality monitor locations in the Rim Fire area.
Thursday, September 12, 2013
Not much changes from Wednesday as we go into Thursday. Similar morning impacts can be expected in areas where the inversion will cause smoke to settle (Figure 6). Afternoon thunderstorm chances are lower than for Wednesday, but still possible. Transport winds may begin to turn a little more northerly late in the day as high pressure begins to rebound over southern and central California, sending smoke toward the Yosemite region (Figure 7). Nighttime easterlies will begin to strengthen over the next couple days, but impacts will likely remain about the same for the Yosemite region and San Joaquin Valley foothills due to reduction in emissions from the Rim Fire.
Figure 7 2km BlueSky particle model prediction for 16:00 9/12/2013. Predictions north of the white line are for the American fire which is not producing emissions at this level and should be disregarded.

Friday, September 13, 2013
Morning smoke impacts will be similar to Thursday, possibly extending slightly further into the San Joaquin Valley due to an increase in the strength of nighttime easterly winds. Smoke dispersion conditions worsen, with very light transport flows and lowering mixing heights. Diurnal upslope/upcanyon winds may provide some limited clearing during the afternoon, but mostly smoke will linger through the day (Figure 8). Smoke production should begin to lessen as the Rim fire nears full containment, currently expected on September 20, relieving some of the potential impacts of the deteriorating atmospheric conditions expected over the weekend.

Figure 8 2km BlueSky particle model prediction for 16:00 9/13/2013. Smoke predictions above the white line are for the American Fire which is no longer having air quality impacts and should be disregarded.
Long Term Forecast:      
Poor smoke dispersion conditions through the weekend. Reduction in the amount of emissions from the Rim Fire as containment is reached should lessen impacts. Southwest winds and normal temperatures may return by the middle of next week.


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