October 17, 2009
Code Orange PM2.5 in San Joaquin Valley, California due to Haze; Extremely Dangerous Hurricane Rick Strengthening off Southern Coast of Mexico
It's a quiet day for air quality across most of the nation, with Code Green (Good) conditions prevalent across the Central and Eastern portions of the country. The exception is California's San Joaquin Valley, where PM2.5 levels are Code Orange (Unhealthy for Sensitive Groups) due to widespread haze. The haze is not visible in today's MODIS Terra true color image (below on upper left, overlaid with current AQI values in Google Earth), but I know it's there because Automated Surface Observing Stations (ASOS) across the San Joaquin Valley are reporting haze. Visibility is reduced as a result; at this hour, visibility is reported as 4 miles in Bakersfield (KBFL), 6 miles in Fresno (KFAT), and 2 miles in Merced (KMCE). Calm winds and a moist airmass over the region are providing favorable conditions for haze formation. The evolution of the Code OrangePM2.5 conditions are shown in today's loop of AQI values for California (below on right, courtesy of AIRNow), and more details of the current AQI values are given by the San Joaquin Valley Air Pollution District (below on lower left). Haze will likely continue to be a problem tomorrow, as the San Joaquin Valley Air Pollution District is forecasting Code Orange PM2.5 for Kern County on Sunday.
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In the Pacific, off of the southern coast of Mexico, Hurricane Rick is currently a dangerous category 4 storm on the Saffir-Simpson scale. A GOES IR image of the hurricane (below on left, courtesy of NOAA) shows its tight formation and well-defined eye. The National Hurricane Center (NHC) expects Rick to strengthen to an extremely dangerous category 5 storm over the next 12 hours. Rick is forecast to move parallel to the coast until Monday afternoon, when it will make a turn to the north-northeast and weaken somewhat before eventually making landfall on the Baja California coast sometime on Wednesday (forecast track below on right, courtesy of NHC).
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