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Red Flag Watches & Warnings The Red Flag Program The Red Flag Program is a means by which the National Weather Service (NWS) informs fire management agencies of the onset or possibility of Red Flag events, that is, critical weather and fuel conditions that could lead to extensive wildfire occurrences, or extreme fire behavior. Red Flag Criteria Red Flag events normally require the combination of HIGH to Extreme fire dangers and critical weather conditions. These weather conditions include, but are not limited to: 1. Significant increase in surface winds. (Sustained winds of 20 mph with stronger gusts possible.) 2. A dry thunderstorm outbreak. 3. Significant decrease in relative humidity. 4. Significant increase in temperature. 5. Fire episode of thunderstorms after a hot and dry period. 6. A Haines index of 6.* 7. Any combination of weather and fuel moistures conditions that could cause extensive wildfire occurrences. FIRE WEATHER WATCH: A Fire Weather Watch is issued to advise user agencies of possible development of Red Flag conditions in the near future. A watch shall be issued when a forecaster is reasonably confident that a Red Flag event will occur within the next 12-72 hours. The Fire Weather Watch shall remain in effect until the forecaster determines that the critical weather conditions are imminent or are occurring, or until it can be determined that the expected event will not occur, and thus the watch will be canceled or allowed to expire. RED FLAG WARNING: A Red Flag Warning is issued to advise user agencies of the imminent or actual occurrence of Red Flag Conditions. The Warning will be issued immediately when the forecaster becomes aware of ongoing Red Flag Conditions, or when highly confident that a Red Flag condition will occur within the next 24 hours. SUMMARY: RED FLAG WARNING Red Flag is the term used by fire weather forecasters to alert forecast users to an ongoing or imminent critical fire weather pattern. Dangerous combinations of temperature, relative humidity, and/or wind are forecast. When linked with dry fuel or drought conditions, a Red Flag Warning means conditions are right for new fires and the rapid spread of existing fires. The public should restrict or suspend ALL outdoor burning during a Red Flag Warning! New wild fires should be immediately reported through 911. During Red Flag Conditions, the dangers involved in fire suspension dramatically increase. Citizens are cautioned against attempting to fight wildfires. Should a wildfire occur during Red Flag Conditions, the public should monitor local media for information and/ or evacuation announcements. More info than you needed? Good! *D.A. Haines developed the Lower Atmosphere Stability Index, or Haines Index, for fire weather use. It is used to indicate the potential for wildfire growth by measuring the stability and dryness of the air over a fire. It is calculated by combining the stability and moisture content of the lower atmosphere into a number that correlates well with large fire growth. The stability term is determined by the temperature difference between two atmospheric layers; the moisture term is determined by the temperature and dew point difference. This index has been shown to be correlated with large fire growth on initiating and existing fires where surface winds do not dominate fire behavior. The Haines Index can range between 2 and 6. The drier and more unstable the lower atmosphere is, the higher the index. The Haines Index
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