Thursday, September 12, 2013

9/12/2013 Rim Fire Extended Air Quality Report

As air quality impacts continue to diminish over the next several days this report format will be replaced with situational updates posted as necessary if the forecast indicates smoke impacts from the Rim fire are likely.

Rim Fire, Air Quality Resource Advisor Report                            Thursday, September 12, 2013
 Prepared by: Ryan Bauer, Leland Tarnay, and Sharon Grant
Key Points:
  • The fire size is currently 255,560 acres and remains 80% contained.  About 350 acres of growth occurred yesterday. All but 5 of those acres burned in green islands within the fire perimeter. Roughly 4,300 acres of green islands remain within the perimeter. Only 5 acres of new growth occurred on the eastern portion of the fire near Lake Eleanor.
  • Hotter and drier conditions will return today and tomorrow. Instability remains significant enough for a slight chance of thunderstorms along the Sierra crest. Spotting is still a concern as islands continue to burn within the fire’s perimeter.  Slope and drainage winds will be fairly light except where they align with west facing drainages in the afternoon. Easterly winds will remain fairly weak tonight, but increase tomorrow into 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 9/12/2013 showing MODIS satellite heat detections for the past 12 hours from 08:45, 9/12/2013 (Orange). MODIS did not detect any heat within the past 6 hours so older data are shown.

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 350 acres burned within the fire perimeter, leaving approximately 4,300 acres of remaining islands to produce emissions over the next several days (Figure 2). Only 5 acres of growth occurred within the timber stringers east of the fire that terminate in the rocky peaks of the Yosemite Wilderness.

Satellite imagery from this morning showed the fire area obscured by clouds. Smoke was not visible but monitoring data indicate that morning impacts similar to yesterday are likely to occur as the inversion breaks. Due to the further reduction in acres burned some of these impacts may be a bit lighter today, but less mixing and transport of smoke may produce more concentrated localized impacts such as those seen last night in Tuolumne Meadows.

Figure 3 3-hour average fine particulate (PM 2.5) concentration at seven (7) 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 3).
As expected, air quality within Yosemite National Park has deteriorated with the return of poor dispersion conditions and light northwesterly transport flows (Figure 3). Impacts yesterday evening were in the unhealthy for sensitive groups range in Tuolumne Meadows and nearly so in the Yosemite Valley. Similar conditions are likely through Saturday.
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 Thurs.
Sept 12, 2013
Yesterday, Sept. 11
S. Lk. Tahoe Carson City Mariposa
La Grange

Air quality is satisfactory and poses little or no health risk
S. Lk. Tahoe
Bear Valley
Bear Valley
Greeley Hill
El Portal
Yosemite Vly
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

Groveland Tuol. Mdws
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.
Yosemite Vly
Tuol. City
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.

Thursday, September 12, 2013
Light downslope winds and a moderate inversion caused smoke to drain down the Clavey and Tuolumne River Drainages. Smoke impacts in the communities of Pinecrest, Columbia, Groveland, Greeley Hill, La Grange, El Portal, and Mariposa will be about the same as yesterday reaching their highest intensity early in the day and improving by afternoon. With transport winds still fairly light smoke impacts will remain localized. Evening impacts can be expected again for Tuolumne Meadows and Yosemite Valley with northwest transport winds forecast. Impacts are also predicted further southeast in the Mammoth area, but the concentrations predicted are likely significantly over-predicted (Figure 6). Diurnal upslope/upcanyon flows will be the dominant surface winds. A slightly chance of thunderstorms over the Sierras again today could aid smoke dispersion some in the late afternoon. Easterly winds will remain fairly light again tonight keeping impacts localized and probably not extending into the San Joaquin Valley.

Figure 6 2km BlueSky particle model prediction for 16:00, 9/12/2013 showing air quality monitor locations in the Rim Fire area. Smoke predictions above the white line are for the American Fire which is no longer having air quality impacts and should be disregarded.
Friday, September 13, 2013
Similar morning impacts can be expected in areas where the inversion will cause smoke to settle (Figure 7). Transport winds may be a little lighter, taking longer to clear smoke from foothill communities. Afternoon thunderstorm chances are lower than for Thursday. Northwesterly ridgetop winds will continue to send smoke toward the Yosemite region, which is likely to settle in the Tuolumne Meadows and Yosemite Valley basins in the evening (Figure 8). Nighttime easterlies will strengthen a bit, possibly moving smoke a little further into the San Joaquin Valley.
Figure 7 2km BlueSky particle model prediction for 07:00 9/13/2013.

Figure 8 2km BlueSky particle model prediction for 17:00, 9/13/2013.

Saturday, September 14, 2013
Morning smoke impacts will be similar to Friday, possibly extending slightly further into the San Joaquin Valley due to an increase in the strength of nighttime easterly winds (Figure 9). Smoke dispersion conditions remain fairly poor with light transport flows. The model is hinting at a more west-southwesterly component to afternoon transport on Saturday, potentially shifting smoke impacts a little north into Bridgeport and Lee Vining, but the Yosemite region is still within the area of impacts as well. Diurnal upslope/upcanyon winds may provide some limited clearing west of the fire during the afternoon, but mostly smoke will linger through the day (Figure 10).
Figure 9 2km BlueSky particle model prediction for 07:00, 9/14/2013.

Figure 10 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:      
Sunday looks like the transition day when a low pressure trough approaching the coast will reinstate the southwest flow over the region. Temperatures will cool and all areas south and west of the fire will get some clean air. Depending on the amount of emissions still coming from the Rim fire by next week, communities north and east of the fire could see some smoke return to their area.


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