The History of Fire Weather Services in Hawaiʻi

Early research (Burgan et al., 1974) showed that a significant fire problem existed in Hawaiʻi, with a high frequency of fires occurring on the densely populated island of Oʻahu. At the time, fire agencies across the Hawaiian Islands “relied on past experiences to estimate fire danger” (Burgan et al., 1974). In order to make the process of determining fire danger more objective, Burgan et al. (1974) developed the Hawaiʻi Fire Danger Rating System 1974 (HFDRS 1974). This system was designed to calculate various fire danger indices based on weather observations that were called-in daily to the National Weather Service Office in Honolulu, Hawaiʻi (HFO). Unfortunately, due to maintenance difficulties, HFDRS 1974 fell into disuse after a few years; and the fire weather program remained relatively inactive through the early 1990s.

HFO began providing limited fire weather services in the late 1990s. The current fire weather program began in the early 2000s with the issuance of routine Fire Weather Planning Forecasts (FWF) and Spot Forecasts (FWS) and was expanded to include a Red Flag Warning (RFW) program in 2008. HFO currently uses the Keetch-Byram Drought Index (KBDI) (Keetch and Byram, 1968) at a single leeward site on Oʻahu, Hawaiʻi (Honolulu International Airport; PHNL) to characterize fuel conditions across the state based on observed rainfall and maximum temperature. Dolling et al. (2005) found a strong statistical relationship between composite, island-wide KBDI and fire activity on all Hawaiian islands, except Kauaʻi, and also showed that the driest leeward station on each island could serve as a reference station to diagnose fire activity. PHNL was chosen due to its ability to provide reliable real-time data in the early 2000s. Since then, the Remote Automatic Weather Station (RAWS) network has expanded to 50 sites across the Hawaiian Islands, with most islands having at least one leeward RAWS. With the increase in RAWS stations across the state and the recent devastating wildfire in Lahaina, Maui in August 2023, HFO is currently evaluating its fire weather program.

This presentation will explore the history of fire weather services across Hawaiʻi. It will also discuss the current state of fire weather services in Hawaiʻi, paying particular attention to the performance of the RFW program. Finally, this presentation will examine the various options being considered to help enhance the RFW program and improve future fire weather services across the islands.

References

Burgan, R.E., Fujioka, F.M., and Hirata, G.H., 1974. A fire danger rating system for Hawaii. Fire Technology 10(4):275-28. https://doi.org/10.1007/BF02589985

Dolling, K., Chu, P., and Fujioka, F., 2005. A climatological study of the Keetch/Byram drought index and fire activity in the Hawaiian Islands. Agricultural and Forest Meteorology 133:17-27. https://doi.org/10.1016/j.agrformet.2005.07.016

Keetch, John J. and Byram, G.M., 1968. A Drought Index for Forest Fire Control. Res. Pap. SE-38. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment Station. 35 p.