August 12, 2014

Fires in Pacific Northwest; Moderate AQIs in East

The EPA AQI loop below (top left) shows most of the Plains States and southern Rockies clear, with some areas of Moderate AQI from the Great Lakes into the Southeast, with a few smaller spots across New England and the Mid-Atlantic. One of the areas in Georgia got up to Unhealthy for Sensitive Groups early in the day before dropping back down. The Pacific Southwest has its own areas of Moderate AQI briefly reaching Unhealthy for Sensitive Groups, while the Pacific Northwest and northern Rocky Mountains are largely at Moderate AQIs or above. There are sustained regions of Unhealthy and Unhealthy for Sensitive Groups in northern Washington and central Idaho. NWS surface smoke predictions below (top right) show regions of smoke blanketing the Pacific Northwest and southwestern Canada, which makes that a likely cause. The USDA Large Incidents report shows upward of a dozen fires in the area feeding into the smoke, shown bottom left below, lends credence to that hypothesis.

Most of the Pacific Northwest has been under Red Flag Warnings due to the dry and windy conditions, so the fires there have plenty to work with. The NWS Storm Prediction Center's Fire Weather Outlook for tomorrow, below left, shows an increased risk for fires, so it may be a while before the fires are no longer an issue. The morning radiosonde from Spokane, WA, shown below right, shows a low inversion which, if not broken by diurnal heating, would keep all the aerosols causing the elevated AQIs near the surface, prolonging the event.

Posted by John Sullivan at August 12, 2014 9:57 PM
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