Historic rain/snow event continuing in California!
A classic "Pineapple Express" flow pattern has been pounding parts of California with record-breaking rain and snowfall over the past few days and should continue through Wednesday night. The extremely moist jet stream of Hawaiian origin can be seen clearly in the water vapor image at left, continuing northeast all the way through the Sierra Nevada mountains where up to 13 feet of storm total snow has been reported already. The main culprit for this flow pattern is the negative North Atlantic Oscillation phase, which typically causes stagnant and blocking flow patterns, and a near stationary and very intense upper-level low wobbling just off the Pacific Northwest Coast. La Nina events in the Pacific are also associated historically with very wet conditions in the Pacific Northwest, and a full-blown, mature La Nina is holding strong. Mammoth Mountain, CA is the hardest hit area in terms of snowfall so far, with 8.5-13 feet of new snowfall and an unofficial report of a 155 mph wind gust on top of the mountain yesterday. This month is only 5 inches shy of the snowiest December on record for Mammoth, and with another 3-6 feet expected through Wednesday night, I'd say it's a done deal. In fact, Mammoth Mountain currently
has more snow on the ground than any other location in North America (
www.MammothMountain.com). Over 4 inches of rain fell in Los Angeles over the last few days with residents near burn areas on high alert for mudslides, especially given that another 4 inches could easily fall over Southern California before this storm is over. The effects are beginning to spill east of the Sierra Nevadas as well, with winter storm warnings in effect for most mountain regions in the Western U.S. where a couple feet could easily fall before Christmas Eve. We really should have been in the Sierra Nevadas for this snowstorm. TVN will deploy for the next one!
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