[californiadisasters] Dry Start for 2012 Could Raise Fire Risk

Dry start for 2012 could raise fire risk

posted by Pat Brennan, O.C. Register science, environment editor

January 9th, 2012, 4:32 pm

Dry conditions could extend through early spring in Southern California, ratcheting wildfire risk into the 'above normal' range for parts of Orange County, according to National Forest Service forecasters.

A weak La Niña pattern helped keep December largely dry, and while fall rains encouraged a bit of a "green up" in the hills, those grasses could soon dry out — providing potential ignition points for spring fires.

Wildfire risk should be above normal for the Santa Ana Mountains and nearby areas in Orange County in late winter and early spring, said Tom Rolinski, meteorologist with the Forest Service's Predictive Services Group — with more red-tinted "above normal" zones on its February to April Seasonal Outlook map.

"It looks worse than what we're actually thinking," Rolinski said. "This time of year, you don't get many, if any, large fires. If you look at the map, with above-normal everywhere, it looks really bad, but we're not saying we're going to have all these horrendous fires. We're thinking, a little bit more fire activity."

That means wildfire might be possible in a season where we normally would expect no large fires.

The periodic cooling of the waters of the eastern tropical Pacific, known as La Niña, is likely a factor in keeping things dry, Rolinski said, although La Niña's effects are often over-emphasized at the expense of other patterns affecting precipitation.

Last year, for instance, a "negative Artic oscillation" helped bring low-pressure air systems and powerful storms to the region despite a stronger La Niña in the Pacific.

This year, a positive oscillation may be helping increase high pressure, fostering drier conditions, the Seasonal Outlook says.

Rain and snowfall in the region should be below normal for the remainder of winter and early spring, the Outlook says, with fire potential remaining normal until it shifts toward above normal at the beginning of April.

Dry conditions are already registering on rain and snow gauges around the state.

California mountain snow levels on Jan. 3 were among the lowest ever recorded, only 19 percent of normal for that time of year.

Rainfall totals in Santa Ana, meanwhile, were more than an inch and a half below normal for December.

Recent years have seen below-average levels of wildfire in California's national forests, said spokesman Stanton Florea.

2011 saw 1,049 forest fires that burned 41,777 acres — well below the 10-year average of 490,000 acres.

Wildfire levels have been lower since the large, "outlier" year of 2008, when more than a million acres burned, mostly due to lightning-caused fire in Northern California.

The southern half of the state saw 178 lightning-caused fires in 2011 that burned 21,831 acres in national forests, and 403 human-caused fires that burned 10,736 acres.

Source: http://sciencedude.ocregister.com/2012/01/09/dry-start-for-2012-could-raise-fire-risk/166389/

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