Many Pineapple Express events follow or occur simultaneously with major arctic troughs in the northwestern United States , often leading to major snow-melt flooding with warm , tropical rains falling on frozen , snow laden ground . Examples of this are the Christmas flood of 1964 , Willamette Valley flood of 1996 , New Year 's Day Flood of 1997 , January 2006 Flood in Northern California , Great Coastal Gale of 2007 , January 2009 Flood in Washington , and the January 2012 Flood in Oregon
Christmas flood of 1964
Christmas flood of 1964
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