2007 Western United States freeze

January 13–17, 2007 high/low temperatures

The Western United States freeze of 2007 was a weather event affecting California, Oregon, and Washington from January 12 to January 18, 2007. An Arctic low pressure system dipped extremely far west, resulting in record cold temperatures in the western states, damaged citrus crops in California, and extremely unusual snow accumulation occurring in areas of Southern California.

Buildup

An unusually mild winter across many parts of the Southwest and Pacific Northwest paved the way for an extreme blast of Arctic air that dipped extremely far south causing Arctic snow conditions in the Pacific Northwest and unusually frigid temperatures in Southern California and the San Joaquin Valley. December brought extremely dry conditions for Southern California as well as unusually warm weather, with relatively little cloud cover in the area. Los Angeles averaged well over 3 degrees above average for the month of December. In the Pacific Northwest, the area was continually blasted with unusually large rain storms, causing flooding in much of Washington and Oregon. Temperatures began to drop below average in the San Joaquin Valley beginning January 11 and January 12 in California. The first freeze occurred in the San Joaquin Valley around midnight on January 13. During this time, the middle of the nation was being affected by a severe ice storm system caused by the tail end of the same arctic air afflicting the west.

Impact

The invasion of cold air ranged from January 13 to January 18, 2007 and affected several areas of California, Oregon, and Washington in different ways.

Southern California

Heavy snowfall in San Bernardino, California

Areas that rarely experience snow in Southern California received a glimpse of it during this cold spell. January 17 brought snow to areas of Malibu and West Los Angeles. Snow was reported nearly down to sea level during this cold snap. However, no precipitation fell during January 14, January 15, or January 16 in the area, when temperatures were at their coldest. Records were set across Southern California for temperatures. January 14, 2007, saw a low of 36°F (2°C) in downtown Los Angeles, a record for the day.^[1] San Diego bottomed out at 36°F and 35°F (2°C) on consecutive mornings. Lancaster, a city set in the high desert of Los Angeles County, reached just 3°F (-16°C).^[2] Many sections of the Grapevine freeway were closed due to snow, and several accidents occurred as a result of black ice.

Other consequences of this cold snap in Southern California were dying palm trees and other tropical plants that had thrived here.

In the San Diego region, areas that usually do not see snow, such as the inland areas of La Mesa (540 feet), Spring Valley (390–459 feet) and Mt. Helix (1,386 feet) saw snow flurries early in the morning (around 8:30 a.m.) following the initial passage of the cold front that brought the unusually cold air mass. A small eddy just off the coast spun up some moisture at the same time record low temperatures in the 20's had been recorded. This caused snow flurries to fall in said areas, as well as other communities at similar altitude, such as nearby Lemon Grove, and even at the Rancho Bernardo office of the National Weather Service. Of course, it didn't stick and concluded by 10 a.m.

The San Joaquin Valley

The San Joaquin Valley is the largest citrus producing region in the United States, and the production of these fruits was adversely affected by this weather system. Cold-sensitive plants that grow in this area such as oranges, lemons, avocados, and flowers were greatly damaged due to the cold because they cannot tolerate a hard freeze. Temperatures in Los Banos, California, dipped to 21°F (-6°C) on both January 14 and January 15. An estimated 75% of the nation's citrus crop has been destroyed by the cold weather, with damages to some other crops such as strawberries and avocados and even fresh-cut flowers. The total damage in the area was estimated at around $1 billion. Governor Arnold Schwarzenegger requested federal disaster aid.^[3]

Washington and Oregon

The states of Washington and Oregon are much more prepared for cold temperatures, since they frequently receive them. However, Seattle, Washington, dipped to 17 °F (-8.3 °C) on January 14,^[4] and during this storm on the 16th and 17th, snow was recorded in record amounts in both Washington and Oregon, with some areas receiving upwards of 12 inches (30 cm) of snow in the valleys, and 50 inches (1.3 m) in the mountain areas over the two-day period. This benefited the local ski resorts in the Cascade Range and Sierra Nevada.

See also

• January 2007 North American Ice Storm
• Global storm activity of 2007

References