[californiadisasters] Signs of La Nina, and higher fire risk

Signs of La Nina, and higher fire risk

By Gary Robbins

San Diego Union-Tribune

Originally published June 24, 2010 at 6:07 a.m., updated June 24, 2010 at 8:29 p.m.

Updated: 2 p.m., Thursday

New satellite images of the eastern Pacific show that a fading El Nino has given way to an emerging La Nina -- a change that could result in more frequent wildfires in distant San Diego County later this year.

La Nina typically results in below average rainfall, which allows the landscape to remain drier for longer periods of time, often resulting in more wildfires. The grasses that sprouted to life after last winter's rains have already turned brown or yellow in many parts of eastern San Diego County. And NOAA said last week that this summer could turn out to be warmer than normal, which would hasten the drying process countywide.

East county is a special area of concern because it sometimes gets summer thunderstorms whose lightning can start wildfires.

Scientists detect El Nino and La Nina by monitoring changes in sea surface temperatures in the central equatorial Pacific. Above average temperatures represent El Nino, which can enhance winter rainfall in Southern California. Cold temperatures represent La Nina, a natural, periodic drying trend.

Southern California was under the influence of El Nino during the past winter. And for awhile, it appeared that San Diego would finish the rainy season (July 1-June 30) with above average precipitation. But the city has recorded 10.55'' of rain so far this season. That's about one-quarter inch below average, and significant rain isn't expected for the rest of June, although the marine layer will be thick the next couple of days.

"The next few months will reveal if the current cooling trend will eventually evolve into a long-lasting La Nina situation," Bill Patzert, a Jet Propulsion Laboratory climatologist said in a statement.

San Diego seasonal rainfall (July 1-June 30).

The historic average annual rainfall at Lindbergh Field is 10.7''

2009-10: 10.55''

2008-09: 9.15''

2007-08: 7.25''

2006-07: 3.85''

2005-06: 5.42''

Source: http://www.signonsandiego.com/news/2010/jun/24/grsq-la-nina-takes-hold-could-worsen-wildfires/?sciquest

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