California gets most of its precipitation during winter. But the last two were below average, and 2013-14 is off to a dry start. Blame the prolonged dryness on the "Pacific Decadal Oscillation."
By Patrick Healy | KNBC-TV Los Angeles
Saturday, Dec 28, 2013 | Updated 12:21 PM PSTWith no significant moisture in the forecast and just days until New Year's Eve, it appears this year will go down in the books as the driest ever on record in Los Angeles.
Since the last Rose Parade, only 3.6 inches have registered on the official gauge located on the USC campus and monitored by the National Weather Service.
That's nearly half an inch less than the previous low of 4.08 recorded in 1953 and 1947.
"It's really dry," said JPL's renowned climatologist Bill Patzert, also known for his turn of a phrase. "As dry as a box of popcorn in the desert."
What's worse, the two previous winters were also below normal.
Last week, Gov. Jerry Brown activated a "Drought Task Force," though he has yet to issue an official drought declaration.
Last month, California's Department of Water Resources announced an allocation of only 5 percent of deliveries requested by public agencies from the State Water Project. The initial projection historically is revised during the season.
"We hope things improve with this winter's storms," said Water Resources Director Mark Corwin.
"But there is no guarantee that 2014 won't be our third consecutive dry year."
The Southland's main wholesale water importer, the Metropolitan Water District, reported last October that it has adequate supplies of stored water to get through another dry year. Its primary reservoir, Diamond Valley Lake, is at 72% of capacity, according to MWD Spokesman Armando Acuna.
Water suppliers and distributors have been encouraging Californians to continue conservation measures that date back to the last official drought in 2007. Yard watering is limited to three days a week in Los Angeles and numerous other cities.
"Whatever's necessary to maintain our water, I'm wiling to do," said Leroy Welch, who has reduced yard watering to one day a week at his east Pasadena home.
Over the years, conservation has resulted in significant reductionin water use. As of last summer,
DWP water usage since 2007 had fallen 20 per cent, according to Penny Falcon, DWP Water Conservation Manager.
But due to the dry conditions this past year, DWP has been purchasing as much as 80 percent of the water it delivers to customers.
Meantime, parks and beaches have been busy this end of year holiday week as Southlanders enjoy the prolonged unseasonably warm weather, with temperatures creeping into the 80s and relative humidity dipping into single digits.
"I love the weather," said Corrine Tomlinson of Sierra Madre as she cheered on three generations of her family in a game of touch football. "But I would like to see a little rain."
Meteorologists attribute the current heat wave to a strong, northern jetstream, and lingering high pressure over the great basin.
But climate scientists see the impact of a much larger and more long-lasting pattern known as
the Pacific Decadal Oscillation.
This longterm fluctuation of Pacific Ocean water surface temperature is believed to cause cyclical changes in climate, Patzert said. In the Southwest, the 1980s and 1990s were marked by numerous wet, "El Niño" winters, during which the Central Pacific is warmer than usual.
Since then, Patzert said, the PDO has entered new phase, with cooler ocean water, producing more "La Niña" winters.
"The West and Southwest are in the throes of 13 years of a drought," said Patzert, adding it may be the 2020s before the PDO phase reverses back.
However, year to year weather still varies markedly in a PDO phase. For example, the winter of 2004-05 was LA's wettest in more than a century.
To describe winters with neither an El Niño nor La Niña condition, Patzert coined the term, "La Nada" (the nothing).
La Nada winters can see extremes either way. The heavy rains of 2004-05 came during
a La Nada winter.
January and February historically are Southern California's two wettest months.
"After New Year's, I'm hoping the skies open up," Patzert said.
To augment local water supplies, The Los Angeles Department of Water and Power and other cities have had to import more water from the Colorado River and from Northern California through the state water project.
Imported water is often more expensive, and the added cost is passed through to consumers.
The tier one cost for water to DWP customers, for example, has increased significantly
this past year, from $3.96 per hundred cubic feet last January to $4.68, starting New Year's Day, according to DWP's website.
However, other factors affect retail prices, and not all of that increase can be attributed to importing costs.
In any event, the region-wide western drought ultimately limits the amount of water that Southern California can import.
The San Gabriel Valley community of Sierra Madre has long relied on groundwater, but in recent months has augmented its supply by purchasing from the Metropolitan Water District. Residential customers have been given conservation goals, at risk of higher charges.
"That's quite a good incentive, I think," Tomlinson said.
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