Red flag warning
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A Red Flag Warning is a term used by meteorologists. When humidity is even lower than normal and when wind is a factor, fire danger becomes an issue that the National Weather Service focuses on. A Red Flag Warning means high fire danger and the high possibility of a quickly spreading fire in the area within 24 hours.
Red flag watches and Warnings should not be disseminated to the public. The intent of the red flag program is to provide land management agencies with appropriate notification of the likelihood that weather conditions associated with the outbreak of wildfire will occur. Identification of red flag events is a primary responsibility of the forecaster producing the fire weather forecasts. Forecasters will issue a fire weather watch or red flag warning, based on the criteria and timing explained below. Some offices will issue individual products under the product identifier RFW while others will simply highlight the information in the routine fire weather forecast. Red flag criteria are dependent on both weather forecasts provided by NWS offices and the fuel moisture and fire danger assessments provided by land management agencies. The weather criteria for fire weather watches and red flag warnings will vary with each NWS office’s county warning area based on the vegetation, topography, and distance from major water sources.
Depending upon the philosophy of the fire control organization, a separate advisory statement to the public by the fire weather forecast office may be desirable. Fire Danger Statements are issued on an as needed basis, when there is either a very high or extreme fire danger. These conditions are determined and are based on stage of vegetation, expected afternoon high temperature, afternoon minimum relative humidity and daytime wind speed. Also included in the product are any burn bans that may be in effect.
Fire weather watches are issued to alert fire and land management agencies to the possibility of red flag conditions beyond the first forecast period (12 hours). The watch is issued generally 12 to 48 hours in advance of the expected conditions, but can be issued up to 72 hours in advance if the forecaster is reasonably confident. The term “fire weather watch” will be headlined in the routine fire weather forecast and/or issued as a special forecast. The watch will remain in effect until it expires, is canceled, or upgraded to a red flag warning.
A red flag warning is used to alert fire and land management agencies that red flag conditions exist or are imminent. A red flag warning will be issued immediately when there is high confidence that red flag criteria will occur within the next 24 hours, or if those criteria are already being met (Due to forecast uncertainty beyond 12 hours, a fire weather watch will be more often used in the 12 to 24 hour time frame.) When a warning is issued, the term ”red flag warning” will be headlined in the routine fire weather forecast, and/or sent as a special forecast to inform users of the warning. The warning will be continued on subsequent forecasts until no longer valid. A cancellation statement (using the RFW product) should terminate the warning unless the previous message indicated a termination time.
Texas Fire Weather Operating Plan 2005-2006
Fire Weather from NOAA National Weather Service
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