By John Antczak
Saturday, June 30, 2007
LOS ANGELES, June 29 -- Barring a surprise arrival of the kind of gully washers Texas is getting these days, Los Angeles's driest year in 130 years of recordkeeping will go into the books this weekend.
The nation's second-largest city is short nearly a foot of rain for the year from July 1, 2006, to June 30. Just 3.21 inches has fallen downtown in those 12 months, closer to Death Valley's numbers than the normal average of 15.14 inches.
It is much the same all over the West, from the measly snowpack and fire-scarred Lake Tahoe in the Sierra Nevada to Arizona's shrinking Lake Powell and the shriveling Colorado River watershed.
The weather that is withering Los Angeles and drowning Texas are connected, said Bill Patzert, a Jet Propulsion Laboratory scientist who researches the ocean's role in climate variations and has watched a Western drought grow for seven years.
Stationary high pressure has pushed the moisture-bringing jet stream to the north, which has also allowed moist air to linger over Texas, he said.
"This last year, it's definitely like the nail in the coffin," Patzert said of California's drought. "This is where the pain really comes home. One of these droughts -- you kind of creep into it slowly -- and it then takes a long time to get out of it."
Los Angeles has already called for a voluntary 10 percent cut in water use, and in recent months, its fire department has faced wildfires more typical of fall.
While the West is parched, Texas has experienced one of its wettest springs after back-to-back years of record drought.
As of Friday morning, 10.97 inches of rain had fallen for the month at Dallas-Fort Worth International Airport. That is half an inch short of what fell in June 1928, the rainiest month on record.
The weather extremes have a common thread, Patzert said: the jet stream.
"Although we had a lot of storms in the Gulf of Alaska this winter, we had just a big, stationary high-pressure system either offshore or to the east of us, and really what it did was it just drove that rain-delivery jet stream into the Pacific Northwest and just totally bypassed us," he said.
The circulation of high pressure also tends to cause Southern California's Santa Anas, the dry, warm winds that descend out of the high desert north of Los Angeles and are often linked to terrible fires in fall and winter. In the past year, there have been three times the normal number of Santa Ana days, Patzert said, and a "more-or-less continuous fire season."
The shift in the jet stream to the north has also kept rain over Texas, he said.
The central Texas cities of Austin and San Antonio have received nearly twice as much rain as usual for June. And earlier this week, about 18 inches of rain fell overnight near Marble Falls, about 40 miles northwest of Austin. Boats and helicopters rescued people who scrambled atop buildings and vehicles.
Even typically parched West Texas is getting drenched. So far this year, Lubbock had received 17.39 inches of rain -- just over an inch shy of the amount it usually gets during the entire year.