First Storm Gives Way To More Drought
A soaking of much needed rain and blanketing of Sierra Nevada snow delighted parched Central California October 31 and November 1 but the Golden State’s stubborn drought wasted no time in returning dry, fair and unseasonably warm weather to the valley.
Precipitation amounts of about one inch were common throughout much of the valley and in the mountains.
Several inches of snow fell in the higher Sierra with the snowline falling in some areas below 5,000 feet.
FIRST IN SIX MONTHS
It was the first really good storm across much of California in well over six months and one of only a relatively few that have occurred since the drought, now entering its fourth year, began.
This event was a good old fashioned, well defined Pacific winter-type cold front and associated trough of low pressure. It had enough oomph to at least briefly dislodge what seems to have become a permanent ridge of high pressure
blocking storms from entering all but the northernmost parts of the state.
Throughout the Friant Division, the rain that washed out many a Halloween trick-or-treat adventure for disappointed youngsters replaced the deep dust in citrus groves, fruit orchards, vineyards and fields with mud. With the Friant Division and many other valley irrigation delivery systems struggling without water allocations because of the drought and U.S. Bureau of Reclamation and State Water Resources Control Board water management actions, the natural late season irrigation, while too late for 2014 production, was welcomed.
So dry are conditions in the foothills and mountains, however, that the San Joaquin River’s calculated full natural flow at Friant (as if there were no dams) had only a small spike that lasted but three days. During much of this fall, the river’s natural flow has been calculated on several days to have fallen to nothing at all. The U.S. Bureau of Reclamation reported during a November 7 meeting in Visalia that October’s natural runoff was the driest in more than 100 years. Reclamation added that November may set a similar San Joaquin record.
Eight automated San Joaquin River watershed snow sensors on November 5 were showing the early season snowpack water content to be averaging less than three quarters of an inch, 2% of the normal on April 1 when snow conditions are presumed to peak.
MORE HIGH PRESSURE
High pressure quickly built back in during the week of November 3 and long-range forecasts have not proven encouraging. Through November 19, precipitation in most of Northern California is expected to be below average with “equal chances” of above- or below-normal precipitation into early December.
Then, the National Weather Service’s Climate Prediction Center begins to show some modest extended-range improvement. From December through April, charts are suggesting Central and Northern California precipitation may be somewhat above average.
Unfortunately, hydrologists around the state have indicated a water year (ending September 30) that is 150% of average or more would be required to make a decent dent in the drought.
DEPLETED STORAGE
Throughout the San Joaquin River system of reservoirs, which include the U.S. Bureau of Reclamation’s Millerton Lake as well as Southern California Edison Company and Pacific Gas and Electric Company hydroelectric storage facilities, water reserves are largely depleted.
As of November 5, the San Joaquin’s total reservoir storage amounted to 340,848 acre-feet, 30% of available capacity (1,131,900 acre-feet). (Please see water report, Page 2.)
Millerton Lake storage has actually been rising slowly and is 34% of capacity. However, the 179,595 acre-feet behind Friant Dam remains uncomfortably close to the lake’s “dead storage” pool of 135,000 acre-feet, below which releases cannot be made to the Friant-Kern and Madera canals. Millerton storage is nearly 100,000 acre-feet less than it was at the same time a year ago.
Total upstream storage on November 5 was 161,253 acre-feet, 26% of capacity. The total water in storage in all San Joaquin River reservoirs is actually about 180,000 acre-feet less than Millerton Lake’s storage alone.
