July 7, 2008
Fires and Unhealthy Air Quality Continue in California; Code Orange Conditions in Ohio
As we begin the second week in July, the wildfires that started on June 21 are still keeping air quality in the Unhealthy range throughout central and northern California. This afternoon, PM2.5 is Code Red (Unhealthy) throughout the greater Sacramento area. The image below of today’s MODIS Terra true color image overlaid with the 21:00 UTC AQI values shows predominately Code Red and Code Orange (Unhealthy for Sensitive Groups) air quality in the Central Valley. Smoke from the fires is evident across the state, and several distinct plumes can be seen streaming into the Central Valley on its northeast and southeast sides. The National Interagency Fire Center reports there are currently 25 fires in California that have burned over 500,000 acres, and no fires are contained.
The MODIS Terra true color image from the AERONET Moss Landing region (below on left) gives a clear view of the smoke from the fires in central California. Note that the variation in surface color between the left and right portions of the image are due to the different passes of the satellite. The corresponding MODIS Terra AOD image from Region 9 (below on right) indicates elevated AOD associated with smoke from the fires in central California.
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Residents of the fire regions will not get any relief over the next few days. A strong ridge of high pressure is expected to usher a heat wave into California that will peak on Wednesday and Thursday. High temperatures, low humidities, and northeasterly winds will make conditions ideal for fire growth and concomitant poor air quality. Several Red Flag warnings are posted for coastal California and southwestern Oregon for Tuesday through Thursday. A Red Flag warning means that critical fire weather conditions are either occurring now… or will occur shortly. If you live in the warned regions, keep an eye on the existing fires and be on the lookout for new fires to develop over the next 24 to 48 hours.
Across the rest of the nation, air quality is mostly good to moderate, as seen in the image below (on the left) of today’s MODIS Terra true color overlaid with the 21:00 UTC AQI values for the eastern United States. The exception is Ohio, where PM2.5 and ozone are at Code Orange levels. The PM2.5 monitor in Wilmington, Delaware is reading in the Code Red range this afternoon, but that is likely an instrument error, since nearby monitors in New Jersey, Maryland, and Pennsylvania are Code Yellow and Green. No evidence of haze associated with the elevated PM2.5 readings is evident in the nation-wide MODIS Terra true color image, shown below on the right.
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