‘Santa Ana Wildfire Threat Index’ unveiled

A web-based weather monitoring system designed to “quantify” the risks of wildfires during Santa Ana windstorms will equip first responders and the public with the information they need to be prepared for an emergency, officials said Wednesday.

U.S. Forest Service rangers, along with representatives from San Diego Gas & Electric and UCLA, jointly developed the Santa Ana Wildfire Threat Index, which was unveiled during a briefing at the USFS’s Southern California Geographic Area Coordination Center in Riverside.

“Given the current state of fuel conditions, we have the potential to see devastating fires this fall should significant Santa Ana winds occur,” said Forest Service meteorologist Tom Rolinski. “This tool will directly benefit fire agencies by allowing us to better anticipate what kinds of resources may be needed, as well as where and when we could face the greatest challenges.”

The new system gauges the potentiality and probable intensity of wildfire events by examining offshore wind flows and other factors, relying on three decades of Southern California weather data to pattern forecasts.

SDG&E Vice President Dave Geier said the concept came to life following the destructive wildfires that swept through parts of San Diego County in the fall of 2007.

“I asked my team to come up with something similar to the categories to rate hurricanes that could be used to classify Santa Ana wind events based on their potential to spread a major fire, which would help us in making operational decisions to protect our system and our customers,” Geier said.

“The goal was to develop a uniform and recognizable system that also could be used to alert fire agencies and communities in time to prepare and take appropriate action,” he said.

The system encompasses four zones: Los Angeles and Ventura counties; Orange County and the Inland Empire; San Diego County; and Santa Barbara County.

Using SDG&E weather monitors, information from the National Weather Service and historical weather data, the threat index calculates wildfire risks and places them in either of four categories — marginal, moderate, high or extreme.

“This index will help forecasters to quantify a red flag warning and the public to better understand the risk,” said Roger Pierce, director of the NWS in San Diego.

Red flag warnings are disseminated when humidity levels, temperatures, wind speeds and other atmospheric conditions are conducive to wildfire outbreaks.

“We believe this new tool will support and complement our forecasts and provide even more information to help the public to be better prepared,” Pierce said.

Robert Fowell, chair of the UCLA Department of Atmospheric and Oceanic Sciences, led a team of researchers in studying and processing meteorological data from the last 30 years to bolster the threat index’s forecasting capabilities.

SDG&E provided funds for the computer hardware to get the project done.

The Santa Ana Wildfire Threat Index is available online 24 hours a day at http://psgeodata.fs.fed.us/sawti/