With the beginning of March, so brings the beginning of the spring fire weather season for eastern Iowa, northwestern Illinois, and extreme northeastern Missouri. The Fire Weather Forecast Zones (product CHIFWFDVN) forecast.weather.gov/product.php begin on March 1st at 4 pm CST, and will then be issued twice a day around 4 am and 4 pm through May 31st. The Grassland Fire Danger Index (GFDI) will be a part of this product and will be a primary driver of determining very high or extreme fire danger across the area, and the possible need of a Red Flag Warning (product CHIRFWDVN). A Red Flag Warning is generally defined as a forecast warning to inform area firefighting and land management agencies that conditions will be ideal for wildland or cured cropland fire ignition, and rapid propagation. After drought conditions, or when humidity is very low combined with high winds and abundant cured vegetation, the Red Flag Warning becomes a critical statement for state and firefighting agencies to steer their operations. 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.
Again, the extent of the fire danger and need of a Red Flag Warning is generally based on the type and amount of cured vegetation available, expected afternoon high temperatures, afternoon minimum relative humidity, and wind speed. Outdoor burning bans may also be proclaimed by local law and fire agencies based on Red Flag Warnings.
A seperate but less imminent forecast of dangerous fire supportive conditions may include a Fire Weather Watch. This product is issued to alert fire and land management agencies, as well as the public, that the possibility that Red Flag conditions may exist beyond 12 hours of the issued forecast. The watch is issued generally 12 to 48 hours in advance of the expected conditions that may produce high fire danger. The watch then remains in effect until it expires, is canceled, or upgraded to a Red Flag Warning.
Of course, dangerous fire potential early this spring is highly dependant on lingering snow cover or cool moist conditions that may inhibit extreme fire behavior. Although this is the time of year (late winter into early spring) with the most abundant wildland cured vegetation-dead grasses to carry fire, it also can be the most limited by snow cover, cool temperatures and ground moisture. The National Weather Service in the Quad Cities hopes that everybody has a safe and productive spring fire weather season.