How Does LAFD Determine Wildfire Danger in Los Angeles?

Thursday, October 26, 2023

How does the Los Angeles Fire Department decide where to strategically place resources during high wildfire danger?

The answer is science.

Your LAFD utilizes a Burning Index (BI) to determine exactly when and where apparatus and personnel should be pre-deployed. It takes a number of daily procedures to determine the current BI specific to the City of Los Angeles.

First: dead vegetation fuel moisture readings are carefully taken in the early afternoon at Fire Station 108 on Mulholland Drive near Coldwater Canyon, and communicated to LAFD Valley Bureau Headquarters.

Secondly, a group of federal meteorologists at the Southern California Geographic Area Coordination Center (OSCC) in Riverside, California provide a fire weather forecast consisting of a predicted high temperature, low relative humidity, wind speed and direction for the next day. 

Thirdly, historical data (high/low temperature, high/low relative humidity and hours of rainfall in the last 24 hours) is mixed into the brew.

All of this information is fed into equations that make up the National Fire Danger Rating System (NFDRS). The result is the BI. Theoretically, fire danger is elevated when BI’s reach high values. The daily BI level is stated as a numerical value:

BI 0 to 37 = Low
BI 38 to 47 = Moderate
BI 48 to 110 = High
BI 111 to 161 = Very High
BI 162 and above = Extreme

On days of Extreme Fire Danger, your Los Angeles Fire Department may pre-deploy resources at select Neighborhood Fire Stations in-and-near areas prone to wildfire

Not all forecasts become reality, so LAFD Valley Bureau staff conduct real-time weather surveys, monitor Remote Automated Weather Stations (RAWS) in and near the City of Los Angeles and consult the National Weather Service (NWS) to stay abreast of fire weather conditions and forecasts.

The NWS and OSCC may come to different conclusions on the forecast as well, based on which computer model each agency trusts. Ultimately, the LAFD makes decisions on pre-deployment based on all of these inputs – with a lot of experience mixed in. 

⇒ Please remember that radio and television weather reports are broadcast to a wider community than the City of Los Angeles, and the information they share on "Red Flag Warnings", for instance, may *not* apply to the areas served by your LAFD.

Kindly note that LAFD uses the specific term "Red Flag Alert" to indicate forecast or existing "Red Flag" conditions inside the City of Los Angeles. A "Red Flag Alert" is called when the wind speed is 25 miles per hour or more and the relative humidity is 15% or less. History has proven that a combination of strong winds, low humidity and warm temperatures will create explosive fire growth potential. 

For this reason, special parking restrictions may exist on certain narrow streets in brush areas only during “Red Flag Alert” conditions. To determine the current Red Flag Alert Parking Restriction status within the City of Los Angeles, please call 3-1-1 or visit: LAFD.ORG/RedFlag

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