RED FLAG WARNING & FIRE WEATHER WATCH
A Red Flag Warning is issued by the National Weather Service for weather events that may result in extreme fire behavior that will occur within 24 to 48 hours due to forecasted high winds and low humidity combined with low live fuel moistures. A Fire Weather Watch is issued when weather conditions could exist in the next 12-72 hours. During these times, extreme caution is urged for all residents because a simple spark can cause a major wildfire.
Residents can prepare for Red Flag Warnings and Fire Weather Watches by storing patio furniture cushions inside, reviewing their emergency action plan, ensuring their “go bag” is ready and making sure they always have enough fuel in their vehicles for safe evacuation.
The Fire Department, Sheriff’s Department, and City staff participate in daily conference calls with the local National Weather Service office and respond to warnings and watches by increasing staffing and resources. Residents should avoid risky fire behaviors and remain vigilant. If you see flames or smell smoke, call 911 immediately.
The current fire weather forecast can be viewed on the National Oceanic and Atmospheric Administration (NOAA) website.
Live Fuel Moisture
Along with hot dry Santa Ana winds and low relative humidity, Live Fuel Moisture (LMF) is an important component in determining critical fire danger and Red Flag Conditions. LFM is defined as the percentage of water content to dry matter content in live vegetation. Live Fuel Moisture can be as 200% and 60% is considered critical.
The direct measurement of LFM is done by collecting fresh field samples of Chamise, drying them until all moisture is evaporated, and calculating the water content difference between fresh and dry samples. Field-Sampled LFMs are gathered at three locations throughout the Santa Monica Mountains to determine the average LFM in the region.
Chamise is one of the most common shrub species found in the Southern California chaparral communities and is the dominant species in the Santa Monica Mountains region. Chamise is evergreen, but it is sensitive to seasonal drought. During Southern California's long dry season, Chamise leaf moisture content drops as soil water availability declines. In extreme conditions, rapid dry down can happen in days, for example during Santa Ana winds affecting Southern California.
The Los Angeles County Fire Department Forestry Division conducts sampling approximately every two weeks and posts the results on their website.