EXPLANATION OF WHAT TO EXPECT IN REGARD TO BURNING CONDITIONS FOR THE FIVE CATEGORIES OF THE GRASSLAND FIRE DANGER INDEX AND RED FLAG WARNING.

LOW: Low ignition hazard. Dead fuels do not ignite readily from any source.

MODERATE: Medium ignition hazard of dead, fine fuels such as cured grass. Fires can start from accidental causes such as campfires but the number of starts is relatively low. Fires are not likely to become serious and control is relatively easy.

HIGH: Moderately high ignition hazard of dead, fine fuels such as cured grass. Fires can start from most accidental causes. This category denotes "easy" burning conditions, with matches and campfires becoming dangerous. In fact, unattended campfires are likely to escape. On windy days, fires in cured grasslands can burn briskly with moderate rates of spread. However high intensity fires are usually limited unless the fire spreads into a heavy concentration load of cured grass. Fires can be easily contained if hit fast and early in the burn.

VERY HIGH: The Sioux Falls forecast office will issue a formal grassland fire statement if the burning danger reaches this category. High ignition hazard with matches and campfires dangerous. All cured grasslands ignite readily and, immediately after ignition, spread rapidly. Fires will likely become hot enough to ignite live, fine fuels (one-quarter inch or less in diameter) by pre-heating. Short range spot fires are a danger. Fires burning in cured, tall grassy fuels, sawgrass or cattails could develop high intensity characteristics. Fire containment at the head of the fire becomes difficult until the fire environment changes.

EXTREME: The Sioux Falls forecast office will issue a formal grassland fire statement if the burning danger reaches this category. Dangerous burning conditions with all man-made fire starting sources very hazardous. In cured grasslands, expect a quick ignition, rapid buildup and rapid rate of spread. Fires will be hot enough to ignite live fuels one inch or less in diameter by pre-heating. Short range spot fires are likely. The fire can move up tree trunks if it enters a wooded stand. Fires burning in cured, tall grassy fuels, sawgrass or cattails will likely develop high intensity characteristics. Fire fighting on the flanks is possible, but direct attack at the head of a fire is dangerous until the fire environment changes.

RED FLAG: The Sioux Falls forecast office will issue a red flag warning if the burning conditions reach this category. In addition to fuel being dry enough to burn, the three weather factors which must be met are temperatures at or above 75F, wind speeds at or above 25 mph, and relative humidity values at or below 25 percent. In cured grasslands, expect a quick ignition, extreme rate of spread and aggressive burning. Fires will be hot enough to ignite live fuels three inches or less in diameter. Extreme fire behavior is probable if fires reach cured, tall grassy fuels, sawgrass or cattails with short to intermediate range spot fires likely. All fires are serious. Fire intensity is usually high enough that burning of woody fuels with diameters of three inches or less in tree stands is likely. Direct attack on the fire is rarely possible and can be deadly until the fire environment changes. Fire fighting on the flanks is more prudent.


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