A red flag warning is a forecast warning issued by the National Weather Service (NWS) in the United States to inform the public, firefighters , and land management agencies that conditions are ideal for wildland fire combustion, and rapid spread. After drought conditions or a dry season, when humidity is very low, and especially when there are high or erratic winds (which may also include lightning as a factor), the Red Flag Warning becomes a critical statement for firefighting agencies. These agencies often alter their staffing and equipment resources dramatically to accommodate the forecast risk. To the public, a Red Flag Warning means high fire danger with increased probability of a quickly spreading vegetation fire in the area within 24 hours.
6-496: The weather criteria for fire weather watches and red flag warnings vary with each Weather Service office ’s warning area based on the local vegetation type, topography , and distance from major water sources. They usually include the daily vegetation moisture content calculations, expected afternoon high temperature, afternoon minimum relative humidity, and daytime wind speed. Outdoor burning bans may also be proclaimed by local law and fire agencies based on red flag warnings, for both
12-428: A combination of strong winds, very low humidity, long duration, and very dry fuels. It was used for the first time on October 29, 2019. A related but less imminent forecast may include a fire weather watch , which is issued to alert fire and land management agencies to the possibility that Red Flag conditions may exist beyond the first forecast period (12 hours). The watch is issued generally 12 to 48 hours in advance of
18-505: A geographic area of responsibility, also known as a county warning area , for issuing local public, marine, aviation, fire, and hydrology forecasts. They also issue severe weather warnings, gather weather observations , and daily and monthly climate data for their assigned area. The local weather forecast offices also control the broadcasts of weather information on the NOAA Weather Radio All Hazards stations. The NWS
24-485: Is divided into six regions. Prior to the NWS reorganization in the 1990s, each state and territory had its own forecast office — with the exception of northern and southern California; north, south, and west Texas; and upper and lower New England . Local offices (NWSOs) then each maintained their own county warning area, and the official hourly and daily readings at the weather station where they were located, typically at
30-542: The expected conditions, but can be issued up to 72 hours in advance if the NWS agency is reasonably confident. The term “Fire Weather Watch” is headlined in the routine forecast and issued as a product, similar to the other primary fire warning terms. That watch then remains in effect until it expires, is canceled, or upgraded to a red flag warning. List of National Weather Service Weather forecast offices The National Weather Service operates 122 weather forecast offices. Each weather forecast office (WFO or NWSFO) has
36-557: The general public and land management officials. A fire weather warning gives extra guidance to land management officials to refrain from controlled burns . In October 2019, the National Weather Service introduced an enhanced version of the warning, called extreme red flag warning . Analogous to the particularly dangerous situation (PDS) wording on a high-end severe weather warning or watch , this means that conditions for fire growth and behavior are extremely dangerous due to
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