National Weather Service United States Department of Commerce
Understanding Fire Weather

Where do I find out about Current Burn Bans?

Burn Bans are requested by the County Board of Supervisors and approved by the Mississippi Forestry Commission.  County Judges issue burn bans in Arkansas.

Mississippi Burn Bans

Arkansas Burn Bans

Louisiana Burn Bans

 

What is a Drought Statement and under what conditions is one issued?

A Drought Information Statement will be issued when the U.S. Drought Monitor indicates drought intensity at the level of D2 or worse in any portion of the NWS Jackson County Warning Area. They should be issued at least once per month or more frequently during the following circumstances: 1. When drought conditions change, or 2. When local or regional criterion has been met requiring an update.

Latest Drought Information Statement

 

What is fire weather?

Fire weather is the use of meteorological parameters such as relative humidity, wind speed and direction, mixing heights, and soil moisture to determine whether conditions are favorable for fire growth and smoke dispersion. The National Weather Service in Jackson issues several fire weather products on both a daily basis and when conditions warrant. These fire weather products are generally intended for land management agencies in our area such as the United States Forest Service (USFS) and the forestry commissions of Mississippi, Louisiana and Arkansas. These products provide meteorological data which help these agencies make decisions relating to fire weather, such as when to execute controlled burns and when to expect a higher probability of wildfires.

The National Weather Service in Jackson issues a Fire Weather Planning Forecast. This is produced twice daily and provides the above agencies with forecasted weather conditions.  This allows agencies to plan a controlled burn or not based on anticipated weather conditions. Another product that is produced is a Spot Forecast. This is a request from a fire weather agency for specific conditions in a location that might be used for a burn. The forecasters at the NWS will provide forecasted wind, fog, mixing height conditions as well as other parameters, during a specific time period for these requests.

For additional links and fire weather information, please click here to go to NWS Jackson's Fire Weather Page.

What is a Red Flag Warning? What about a Fire Weather Watch?

The criteria for the issuance of a Red Flag Warning varies from state to state. The National Weather Service in Jackson provides fire weather services for our counties in central Mississippi, as well as northeast Louisiana and southeast Arkansas.

Fire Weather Watches/Red Flag Warnings are issued when the combination of dry fuels and weather conditions are such that extreme fire behavior or ignition is occurring or is expected to occur. NWS Forecasters will coordinate with local fire and land managers (State Forestry Commissions/US Forest Service) through the Interagency Coordination Centers of Louisiana...Arkansas and Mississippi to discuss the issuance of a Fire Weather Watch or Red Flag Warning. Below are some of the criteria to consider when evaluating Red Flag/Fire Weather Watch Conditions (conditions approaching this criteria)

When a Red Flag Warning is issued by the National Weather Service, outdoor burning is strongly discouraged. A Fire Weather Watch is issued when there is a potential of Red Flag conditions during the next 12 to 72 hours. 

For Mississippi Red Flag/Fire Weather Watch Conditions:

  • Relative Humidity less or equal to  25%
  • 20 foot wind speed of greater or equal to 15 mph

For Louisiana Red Flag/Fire Weather Watch Conditions:

  • Keetch-Byram Drought Indices of greater than 700
  • Relative Humidity less than 25%
  • Wind speed of greater than or equal to 14 mph

For Arkansas Red Flag/Fire Weather Watch Conditions:

  • Relative Humidity less than 25%
  • 20 foot wind speed of greater or equal to 14 mph
  • Fuels critically dry, 10 hour fuels less than 10 percent

 

What is the KBDI?

The Keetch-Byram drought index (KBDI) is a continuous reference scale for estimating the dryness of the soil. The index increases for each day without rain (the amount of increase depends on the daily high temperature) and decreases when it rains. The scale ranges from 0 (no moisture deficit) to 800 (high moisture deficit). The range of the index is determined by assuming that there is 8 inches of moisture in a saturated soil that is readily available to the vegetation.

 For different soil types, the depth of soil required to hold 8 inches of moisture varies (loam=30", clay=25" and sand=80"). A prolonged drought (high KBDI) influences fire intensity largely because more fuel is available for combustion (i.e. fuels have a lower moisture content). In addition, the drying of organic material in the soil can lead to increased difficulty in fire suppression.

High values of the KBDI are an indication that conditions are favorable for the occurrence and spread of wildfires, but drought is not by itself a prerequisite for wildfires. Other weather factors, such as wind, temperature, relative humidity and atmospheric stability, play a major role in determining the actual fire danger.

 

 

Current KBDI Image