Home > Fire Weather > Fire Weather Forecast Parameter Definitions
| Sky/Weather | Cloud cover (% of sky covered) and weather phenomena forecast during the period. Areal Coverage Descriptions: Isolated = less than 15% Widely Scattered = 15-24% Scattered = 25-54% Numerous/Widespread = 55-100% |
| Max Temperature | The highest temperatures (°F) expected during the forecast period. |
| Min Temperatures | The loweest temperatures (°F) expected during the forecast period. |
| Max Humidity | The highest relative humidity (%) expected during the forecast period. |
| Min Humidity | The lowest relative humidity (%) expected during the forecast period. |
| 20-Foot Wind | The average 10-minute wind speed (mph) and direction 20-feet above the vegetation. |
| Ridge Top Wind | The average 10-minute wind speed (mph) and direction 20-feet above the local higher terrain (hill, butte, peak, etc.). |
| LAL | Lightning Activity Level: 1 - No Thunderstorms 2 - Isolated Thunderstorms - single cell, LT 20 strikes/hour, LT 20 total strikes. 3 - Widely Scattered Thunderstorms - up to 70 strikes/hour, 20-40 total strikes 4 - Scattered Thunderstorms - 25-130 strikes/hour, 40-80 total strikes 5 - Widespread, numerous Thunderstorms - 75-300 strike/hour, 80-160 total strikes. 6 - Dry Lightning Outbreak - generally high-based dry thunderstorms, at least widely scattered in coverage, up to 70 strikes/hour, up to 40 total strikes. |
| Chc of Wetting Rain | The chance of rainfall exceeding 0.10 inches. |
| Transport Wind | Average wind speed (mph) and direction in the mixing layer (surface to mixing height). |
| Mixing Height | Depth of the mixing layer (feet above ground level). |
| Smoke Dispersal | Excellent - 150,000 knot-feet and greater Very Good - 100,000 to 149,999 kt-ft Good - 60,000 to 99,999 kt-ft Fair - 40,000 to 59,999 kt-ft Poor - Less than 40,000 kt-ft |
| Haines Index | Lower Atmospheric Stability Index. The potential for the growth of large, plume-dominated fires. Scale ranges from 2 (very low) to 6 (high). High level Haines is used in WFO Riverton products. |
