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Mother Nature packs a wallop | ||||
February 27, 2004 |
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Following are first-hand accounts from Geosciences faculty John Monteverdi and David Dempsey of the Feb. 25 storm and associated campus floods and power outages which resulted in the canceling of classes for the day. --- Feb. 25, 2004 -- Several small, but very intense thunderstorm cells embedded in the larger frontal system currently impinging upon California passed through parts of the San Francisco Peninsula, including parts of San Francisco, this morning, dumping at least an inch of rain in under an hour in some places. The rain ran off the hills flanking the eastern side of campus and funneled to the low spot on 19th Avenue just east of Hensill and Thornton halls, which are built on the topographic depression that at one time constituted a seasonal stream canyon leading to Lake Merced. We've modified the landscape, but the water still remembers where to go! The surging flood cascaded from 19th Avenue into the depressed area behind the two science towers, washing away part of the embankment beside the road, exposing a large water main, and weakening the roots of several large Monterey pines growing there. That water then formed a temporary, fast-moving river up to a foot deep that flowed around Thornton Hall, past the stadium and eventually into the lower levels of the Lot 19 parking garage, where it overwhelmed the storm drainage system and resulted in water fountaining out of storm grates. More water poured off of 19th Avenue and into the open-air street-level walkway beneath the overhanging Hensill Hall, then cascaded spectacularly down the stairs in front of Thornton Hall or drained down inside both buildings, creating attractive waterfalls down interior stairwells and elevator shafts and in some cases back outside, forming exterior waterfalls from the 3rd floor down. --- Feb. 25, 2004 –- San Francisco State University and southwestern San Francisco County were hit with a torrential rain storm associated with a convective element that passed over the area between 8:30 a.m. and 9 a.m. Unfortunately, our rain gage is out, would you believe it? However, the rainfall was the most intense I have ever seen at San Francisco State since I have been here (1979). I would estimate at least 1 inch in that one half hour. The resulting flooding was awesome. Nineteenth Avenue had water estimated by a chemistry colleague of mine to be 4 feet deep, which then spilled over the sidewalks and down to the play field adjacent to this building. The cascades down that 15-foot section were reminiscent of pictures you see of waterfall/cascades in tropical rain forests. All the streets around Thornton Hall were flooded to about 2 1/2 feet to 3 feet. Students reported that Lake Merced Boulevard had 4 feet of standing water; 19th Avenue through Golden Gate Park was so flooded that cars were up to their hoods and stranded. Nevertheless, it appears that the extraordinary rainfall was local, as many other areas in San Francisco County's northern and eastern portions did not experience this remarkable event. Radar clearly shows one small VIP 5-6 cell, elongated from southwest to northeast about 15 kilometers long, but only about 5 kilometers or so wide approaching our area before the power went out. --- More photos and weather images are available at a Feb. 25 flash flood event Web site put together by Monteverdi.
Feedback?
Contact Ellen Griffin.
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1600 Holloway Avenue, San Francisco, CA 94132 (415) 338-1111 |