The wildfires across California have been covered extensively by the news and social media lately. The Lion wildfire had burned 15,450 acres by early 13 Oct 2017 in Tulare County in central California. This wildfire was in a remote area in the southern Sierra mountains in the Sequoia National Forest, so firefighters would let it burn. It’s position in the middle of the Kern River valley and abundant smoke provided a great visualization of up-valley/down-valley winds (Fig. 1).
At night well after sunset and under an inversion, draining of cold air off the slopes (katabatic winds) converges in the valley and creates relative high pressure, accelerating down-valley. During the day, the slopes and valley floor are heated, creating relative low pressure and upslope and up-valley flow. The smoke from the Lion fire could be seen flowing down-valley just after sunrise in GOES-16 visible imagery (Fig. 2). After a few hours of heating under clear skies, the smoke reverses course and begins to move up-valley. The inversion eventually breaks leading to smoke being dispersed out of the valley as well. The high temporal (5-min) and spatial (0.5 km) resolution from GOES-16 visible imagery and presence of wildfire smoke allowed for this mountain meteorology process to be clearly visualized. Such a reversal of winds in the vicinity of a wildfire is important information for firefighting efforts.
-Bill Line, NWS
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