Haines Index (also known as the Lower Atmosphere Severity Index) is a weather index developed by meteorologist Donald Haines in 1988 that measures the potential for dry, unstable air to contribute to the development of large or erratic wildland fires.[1] The index is derived from the stability (temperature difference between different levels of the atmosphere) and moisture content (dew point depression) of the lower atmosphere. These data may be acquired with a radiosonde or simulated by a numerical weather prediction model. The index is calculated over three ranges of atmospheric pressure: low elevation (950-850 millibars (mb)), mid elevation (850-700 mb), and high elevation (700-500 mb).[2]

A Haines Index of 6 means a high potential for an existing fire to become large or exhibit erratic fire behavior, 5 means medium potential, 4 means low potential, and anything less than 4 means very low potential.[3][4]

The US National Weather Service discontinued use of the Haines Index along with Lightning Activity Level in its Fire Weather Forecasts in December 2024, citing new science that suggested these measures were not as effective as others in forecasting, according to Service Change Notice 24-107.[citation needed]

Beginning in 2018, a team of meteorologists from the U.S. Forest Service and St. Cloud State University developed the Hot-Dry-Windy Index (HDW), a fire weather index intended to address the Haines Index's lack of a wind component.[5] When the National Wildfire Coordinating Group's Fire Weather Subcommittee recommended discontinuing the Haines Index, it identified mixing height — rather than HDW — as the primary replacement metric.[6]

See also

References

  1. ↑ "Haines Index". USA Forest Service. Archived from the original on April 16, 2014. Retrieved 16 April 2014.
  2. ↑ Noaa
  3. ↑ Winkler, Julie A.; Potter, Brian E.; Wilhelm, Dwight F.; Shadbolt, Ryan P.; Piromsopa, Krerk; Bian, Xindi (2007). "Climatological and statistical characteristics of the Haines Index for North America". International Journal of Wildland Fire. 16 (2): 139–152. doi:10.1071/WF06086.
  4. ↑ "Haines index definition". Archived from the original on 2024-01-25. Retrieved 2018-05-20.
  5. ↑ Watts, Andrea; Potter, Brian; Charney, Joseph; Srock, Alan (2020). The Hot-Dry-Windy Index: A new tool for forecasting fire weather (Report). Science Findings 227. Portland, OR: USDA Forest Service, Pacific Northwest Research Station.
  6. ↑ "Replacing Haines Index and Lightning Activity Level". National Wildfire Coordinating Group. Retrieved 2026-08-06.



allikas: https://en.wikipedia.org/wiki/Haines_Index