(a) Wind direction and wind speed data will be determined chiefly through:

(b) Information will be recorded on appropriate forms and diaries. Accurate wind direction predictions may be the most critical factor in effective smoke management. The predicted wind direction establishes which areas shall be allowed to burn to avoid impacts on smoke-sensitive areas.

(c) Since wind direction varies with altitude, the determination and forecasting of winds at all levels anticipated to contain smoke is important. Upper level transport winds will carry a substantial portion of pollutant materials. Since time is required for smoke to mix through all levels, initial impacts may occur far downwind of the burn site.

(d) Surface Winds. Wind flows at the surface will be developed based on wind observations augmented by smoke observations and experience with local terrain-induced flow phenomena.

(e) Upper Wind Levels. From this data, allowing for transverse horizontal dispersion, potential impact areas at long distances (10 to 60 miles downwind) will be identified for proposed burning. If such trajectories indicate substantial impact on sensitive areas, burning will be restricted accordingly in proposed areas. Often the “backward” plume effect will be applied to the wind flow field to determine areas from which burning emissions would cause receptor impacts. To provide for adequate transport and dispersion wind speeds above the surface (2,000 – 10,000 feet) should be five to 20 miles per hour and generally increase with height. [Plan § 3.2, adopted, 10/1/2003.]