[Water_news] 2. DWR'S CALIFORNIA WATER NEWS: SUPPLY -11/18/08

Department of Water Resources

California Water News

A daily compilation of significant news articles and comment 

 

November 18, 2008

 

2. Supply –

 

 

Solar cycles and Sierra weather: Are they related?

Sierra Sun – 11/18/08

By Mark McLaughlin

 

It’s November and skiers and snowboarders are biting at the bit to get out on the slopes. Getting enough natural snowfall in November for skiing is often a challenge in the Sierra, but colder temperatures usually give regional resorts an opportunity to pump out an early base with snowmaking equipment.

At the Central Sierra Snow Laboratory near Donner Pass, November storms are important, as they usually produce more than 10 percent of the average yearly totals, with 48 inches of snow and enough rain to total more than six inches of precipitation. On average, about 75 percent of California’s annual precipitation falls between November and March; half occurs between December and February.

When it comes to weather in the West, averages are hard to come by. More often than not, desiccating droughts are broken by heavy winters, when torrential downpours soak the lower elevations and snow falls thick and deep in the High Sierra. The resulting snowmelt invigorates parched rivers, replenishes empty reservoirs, and resuscitates the withered landscape in a natural cycle as old as the West itself.

Drought-busting seasons come along every so often, but after 100 years, the wild winter of 1906-07 continues to reign as the snowiest on record in the Sierra Nevada. The winter of ’07 ranks as the 10th snowiest on Donner Pass, at just over 7,000 feet. But at the higher elevations the snowfall was epic. Powerful Pacific storms that year buried elevations above 8,000 feet with a snowpack that averaged 30-feet deep, and established California’s greatest seasonal snowfall total of 884 inches — more than 73 feet!

The big winter of 1907 was not entirely unexpected. On Dec. 14, 1906, the Reno Evening Gazette reported, “[Weather] Prophets in various sections of the country and Nevada have been foretelling a long, hard winter, beginning immediately after Thanksgiving.” Weather prophets were purveyors of 19th century Victorian meteorology, who foretold weather events based on natural cycles and spurious astronomical techniques.

The two winters prior to 1907 had been drier than normal, so in the fall of 1906, Western farmers, ranchers and residents were hoping for a big winter to break the drought and fill their rivers and reservoirs. The long-range forecasts proclaimed by weather prophets were often wrong, but this time they got it right. True to predictions, heavy snow invaded the Sierra Nevada on Nov. 21, 1906, the day before Thanksgiving. When the wintry storm stalled in the Great Basin — northerly winds over Nevada and California drove temperatures down to freezing in Los Angeles and San Diego. Snow fell near San Francisco and ice formed in Golden Gate Park.

On Dec. 11, a tremendous blizzard dumped nearly four feet of snow on the Sierra. Hurricane-force winds snapped power lines in the mountains and plunged Reno, Carson City and Virginia City into an eerie darkness. The next day, two seasoned Southern Pacific linemen, Peter Robinson and Fred Rogers, were ordered to find and repair the breaks in the mountains west of Reno. They finished their task near dusk and prepared to ski down, but the sun had set leaving a hard, icy crust on the snowpack. When Robinson began his descent, his long pole slipped from his grasp and he soon was hurtling at breakneck speed down the slope. Rogers sped recklessly after his friend. Nearing the bottom of the hill, both skiers aimed for a 20-foot-high snowdrift. The deep snow buried them completely and saved them from serious injury.

On Jan. 5, 1907, two miners were trapped in the mountains east of Gardnerville, Nev., in an abandoned cabin where they had taken refuge from the snowy gales. Chris Jepperson and Jack Reynolds had floundered helplessly in 15-foot drifts, and now they were stranded at an isolated mine. After three days snowbound without food, the men turned to their one possible savior — Jepperson’s cocker spaniel. They tied a message around its neck, offered a few encouraging words, and forced the dog out into the drifts to die or reach the town of Gardnerville, about 20 miles away. The heroic canine struggled into town three days later, and then it wandered around for two more days before someone noticed the emergency plea for help. Rescuers trailed the exhausted canine back into the mountains where they found Jepperson and Reynolds unconscious, but still alive!

In February the jet stream shifted north, and the harsh weather and frigid temperatures moderated. The welcome respite didn’t last long, however, and March arrived roaring like a lion. Rain and snow were recorded nearly every day of the month. High Sierra locations got plastered with wet, heavy snow, which added another eight feet to the burgeoning snowpack.

The record winter snow of 1906-07 occurred during what climatologists call a “La Niña” event, when sea surface temperatures (SST) in the equatorial Pacific Ocean cool below average. But there may have been another factor that influenced the weather in 1907 as it coincided with a distinct dip, or low value point, in the solar constant cycle. The solar constant represents the amount of the sun’s energy reaching the Earth’s atmosphere and surface.

Scientific measurements first began in the mid-1800s, but more recently researchers have analyzed carbon in tree rings to measure changes in the output of energetic particles from the sun. Today, relatively long and reliable records are now available to profile the fluctuations of solar variability. The word “constant” may be a poor choice — the trend is definitely upwards — with the highest values occurring in the last 50 years. This trend will be one of many factors that has an impact on global climate change.

The sun is the engine that drives all weather on planet Earth, so the winds and circulations of ocean patterns are all affected by the sun’s energy output. From 1890 to 1910, there was a significant drop in the solar constant. Snowfall data from the 125 years of record on Donner Summit indicate out of the top 21 all-time greatest seasonal snowfalls measured there, seven occurred during this period of diminished solar value. In fact, nine out of the top 23 snowiest winters on Donner Summit occurred during the 1890 to 1910 time span.

Remarkably, despite the heavy amounts of snow during that time period, when measured for precipitation (water value), only one of the 20 wettest seasons on Donner Summit occurred between 1890 and 1910. The high snowfall accumulation combined with low water content in these years indicate winter storms were cold, with light, powdery snow, as opposed to the more typical, high-water content snowfall most common in the Sierra.

Although no one can say with certainty a reduced solar value at the turn of the 20th century spawned the record winter of 1906-07, as well as the unusual cluster of snowy winters on Donner Summit around that time, but the anecdotal evidence is certainly food for thought. The media today is mostly focused on global climate change as a result of greenhouse gas emissions, but not all scientists have jumped on the bandwagon just yet. Planet Earth’s climate is always in flux and ever changing. There will always be forces involved that we poorly understand.#

http://www.sierrasun.com/article/20081117/NEWS/811179981/1051&title=Solar%20cycles%20and%20Sierra%20weather:%20Are%20they%20related%3F

 

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

DWR's California Water News is distributed to California Department of Water Resources management and staff, for information purposes, by the DWR Public Affairs Office. For reader's services, including new subscriptions, temporary cancellations and address changes, please use the online page: http://listhost2.water.ca.gov/mailman/listinfo/water_news. DWR operates and maintains the State Water Project, provides dam safety and flood control and inspection services, assists local water districts in water management and water conservation planning, and plans for future statewide water needs. Inclusion of materials is not to be construed as an endorsement of any programs, projects, or viewpoints by the Department or the State of California.