Prescriptions Gary Jarvis Fire Planner National Forests in Mississippi

Demonstrate how to develop prescribed burn parameters Key Points Demonstrate how to develop prescribed burn parameters 2.Demonstrate how to use the BEHAVE program when developing a prescription.

5142.3 – Pre-Ignition Briefing and Forecast Requirements   1. Utilize the most current fire weather forecasts and spot weather forecasts in making pre-ignition decisions. Use the National Weather Service (NWS) or other reputable source (Forestry Commission or SRI meteorologists for example) for fire weather and spot forecasting. 2. Place 10-hour fuel moisture sticks on or near prescribed burn units (or cluster of prescribed burn units) to determine fuel moisture. Each Forest should develop fuel-stick moisture values that provide for the accomplishment of specific resource objectives. Refer to 5140 Exhibit 02, Standards for Prescribed Fire Parameters for the regional standards for fuel moisture. 3. A fire weather forecast from the NWS or other reputable source with 20-foot wind speeds predicted between 15-20 MPH is accepted as compliant with the Regional maximum standard of 18 MPH. Gusts are to be considered as part of the forecast. Predicted 20-foot wind gusts over 20 MPH are out of prescription with regard to wind. 4. Fire weather forecast items should include maximum temperature, minimum relative humidity, maximum 20 foot wind speed-direction (a.m./p.m.), transport wind speed-direction, mixing height, smoke dispersion index, ventilation rate or category day, sky condition, probability of precipitation-duration-amount, frontal passages, and severe weather outlook. Provide feedback to the fire weather forecaster for their fire weather forecasts. Attach forecasts to RxBP.

NF in Mississippi Supplement 5140-93-27 Parameters - Dormant Season – Understory Temperature: <= 72 RH: 30-60% 20ft wind speed: 5-15mph 10 hr fuel moisture: 7-15% KDBI: <300 Ignition probability: <60 NFDRS: Class day A-C Caution: SO Approval >72 25-29% 16-18mph 301-350 D

Behave Runs: Flame Lengths 7 ft ROS 8 Heat Per Unit Area 2694 Fireline Intensity 386 90 38 10 S 8 S 2000 50 60 69 300

It is the day of your prescribed burn, what weather information will you need?

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Mixing Height Wind

Transport Winds Average horizontal wind speed and direction between the surface and the mixing height

Mixing Height The height below which relatively vigorous mixing in the atmosphere is taking place