Sierra Summit

Conversations and observations about California's mountains

January 6, 2009
California and Sierra weather 2008 - Year in Review
    DSC_0158.jpg

         Some 100 miles east of the Sierra Nevada, Death Valley has a well-deserved reputation as one of the planet's hottest places. In 1913, the temperature reached 134 degrees, a world record at the time. (Libya has since topped it by two degrees.)

         Last year, Death Valley - shown here -  set a different kind of warming record: It reached 120 degrees on May 19th, the earliest ever recording for that temperature.

         That is just one of many noteworthy weather events recorded by the Western Regional Climate Center at the Desert Research Institute in Reno, which tracks climate and weather patterns across the western United States.

         Overall, it was another hot, dry year for California: here in the Sierra, it warmed up early - and burned early - then stayed toasty and largely snow-free nto early December. To see my piece on the tardy debut of winter in the Sierra, click on this link:

http://www.sacbee.com/sierrawarming/story/1499249.html

        Climate scientists say the western U.S. is more vulnerable to climate change  than the rest of the country and it sure seemed like that last year.  Two-thousand and eight toyed with us - it started with a bang (big snows in January) and then tapered off into the second year of a statewide drought. The climate center's monthly reports, which are prepared for the federal government, reflect the drama. Here are some of the highlights:

                     January 4-7, 2008: One of the more powerful storms in the past few years slammed into California adding much needed snow in the mountains. Wind damage was severe wiith gusts to as high as 165 mph on the Sierra ridge crests.  Snow pack in the Lake Tahoe area increased from 51% of average on the morning of January 3rd to about 104% three days later.

                     Heavy snow in the mountains of the West pushed the snow pack to near or above normal in nearly all locations by February 1st. In the Sierra Nevada the snow water equivalent increased from 53% of normal at the beginning of the month to about 115% by the end. Rainfall totals range from 8 inches along the north coast to 12 inches in the southern California mountains. Up to 10 feet of snow fell in the central Sierra. In the Owens Valley, Bishop measured an astonishing 4.29 inches of rain on the 4th and 5th, an amount that is 85 percent of its annual average.

                   February  -- A moderate La Nina (cooler-than-usual ocean water on the equator between Peru and the Date Line) has been under way for most of this winter. Typically, this condition is associated with dry winters in the far Southwest and wet winters in the Pacific Northwest and northern Rockies.  

·      March was extremely dry in much of California, tying the driest in 68 years at Sacramento airport with 0.05 inches.  The Sierra Nevada snow pack dropped to about 95 % of normal as of the important April 1st survey; only 17 inches of snow fell near Donner Summit for the month.

·      In April, precipitation was below normal throughout the West.  Many stations in California and Nevada reported their driest March-April total precipitation. While mountain snowpacks were healthy in the Rockies and the Northwest, the central Sierra Nevada snowpack dropped to a dismal 56% of normal.  The Central Sierra Snow Lab, near Donner Summit, CA, measured only 26 inches of snow for March and April combined.  The average is 112 inches."

 

·      In May, temperatures ranged from 2 to 4 degrees above normal in parts of California. Las Vegas, NV, reported a record high of 108F on the 19th  - the same day Death Valley National Park, seen below, topped out at 120. DSC_0279.jpgOn May 23, Bakersfield reported .08 inches of precipitation, breaking an 87-day period with no measurable rain. The climate center reports that statewide, California experienced its driest spring (March-April-May) in over a century.

·      In June, temperature across the 11 western states were almost perfectly split with the northern half two to four degrees  below normal and the southern half two to four degrees above normal. From the 19th to the 22nd southern California suffered through record heat. On the 20th, Santa Maria, on the south coast, recorded it all time highest temperature with 110 F.  Also in June, Gov. Arnold Schwarzenegger declared a statewide drought after 2 consecutive years of below normal rainfall, especially from late winter to early summer. By June 30, much of California had received only 75 percent of its normal precipitation, after a promising start. Many locations recorded less rain over the previous two years than their annual average. June 21st brought dry lightning to much of the northern half of the state sparking over 800 fires and producing very thick smoke.  Unhealthy air quality persisted through the end of the month in numerous California, Oregon and Nevada locations.

·      On July 9th 110-degree heat northwest of Bakersfield led to a vineyard worker dying due to the excessive heat conditions. Parts of the Intermountain West were extremely warm, as well, with Denver recording its second warmest July on record dating back 60 years. On July 12th an intense thunderstorm just north of Mt. Whitney near Independence dropped heavy rain, reportedly 6-7 inches, causing a flash flood and a 300-yard wide mudflow that seriously damaged 25 homes near Oak Creek and closed U.S. Highway 395 for 2 days.

·      In August, temperatures across the West ranged from above normal in the Great Basin and the Southwest to below normal in the Pacific Northwest. California was very warm inland. Redding and Modesto recorded their warmest Augusts on record, as did Reno, NV.

On August 31, a climate station atop White Mountain Summit measured a daily mean speed of 60.6 miles per hours. Another station on Mt Warren, near Yosemite National Park, recorded a mean daily wind speed of 66.3 mph and five hours over 100 mph, highly unusual for summer.  Cottonwood trees were blown over north of Lee Vining, and a kayaker drowned during reported 80 mph winds on adjoining Mono Lake.

§      In September, temperatures were very near normal across the West with slightly below readings in the intermountain region and northwest to slightly above normal in the southwest. Precipitation was generally below to near normal throughout the region.

·    In October, numerous Santa Ana events in southern California led to the highest average maximum temperature (dating back 103 years) in downtown Los Angeles at 84.9 deg F. On the 13th, strong high pressure produced windy and warm conditions across southern California and fanned fires that eventually burned over 20,000 acres and destroyed over 50 residences. One fatality was reported.  A gust to 87 mph was noted at an automated station in the San Gabriel Mountains with extremely low humidities.

·    In November, temperatures were above to well above normal across the West. The average maximum temperature in downtown Los Angeles was 77.7 degrees which combined with October's average maximum temperature of 84.9 was the warmest Oct-Nov average maximum on record.

·    By Dec. 1, warmer temperatures had dropped mountain snowpacks across the region to well below average.  The Lake Tahoe drainage was at 3% of normal and the lake level had dropped to just 2 inches above its natural rim. measured in 2007.

Through December 12th, New Orleans measured more snow than Lake Tahoe, but that changed quickly.  By the end of the month, the Sierra Nevada snowpack had risen from 3% of normal to 85% of normal.

Overall, temperatures across the west, including California, were mostly below normal in December but the dip was not enough to offset another warmer than average year for California and the Sierra Nevada.

In the Sierra, the mean annual temperature in 2008 was 50 degrees, one degree warmer than normal. Overall, 2008 was one of the 20 warmest years in the range since 1895 but more importantly it comes on the heels of nine consecutive warmer-than-average years - a pattern that holds true statewide, too. And that is a concern to scientists who believe it is yet another indication that rising levels of greenhouse gases from the burning of fossil fuels are already starting to influence the state's climate.

"It continues a recent pattern," Kelly Redmond, deputy director of the Western Regional Climate Center told me this week. "Taken as a group, there is no other set of years that looks like that. It says to me there is something new going on."

Photos by Tom Knudson, Sacramento Bee

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About Sierra Summit

The Author
Tom Knudson lives in the Sierra Nevada and travels widely throughout the range. His hobbies include fly-fishing, backpacking and cross-country skiing. He is the recipient of numerous journalistic awards, including two Pulitzer Prizes, one for a 1992 Sacramento Bee series "Sierra in Peril," a watershed work about environmental threats to the mountain range. E-mail Tom at tknudson@sacbee.com.

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