04-25-2026, 06:04 AM
Thanks for pointing that out, you're right:
"One is enhanced rainfall over the mountainous terrain releasing a tremendous amount of heat causing the air to rise and pressures to lower locally, leading to a deflection of the storm towards the island. The second impact is from higher wind speeds near between the mountains and the storm's center due to a funneling effect. This also leads to lower pressure nearer the island and again results in a deflection towards the island."
In addition, many years ago I was in a meeting with representatives from all the observatories and the team at UH's Mauna Kea Weather Center (MKWC - http://mkwc.ifa.hawaii.edu/). The Director of MKWC made a presentation at that meeting about the effects of the wind shadow downwind of Hawaii Island. IIRC, one of them was a potential drop in air pressure SW of the Big Island, which might cause hurricanes passing south of the Big Island to divert north towards Oahu and Kauai. I'll check whether the paper was published.
Interestingly, Hurricane Iniki did exactly that back in 1992. If that's the case, we have two mechanisms that cause storms to head towards the Big Island, which would protect the other islands, but another that creates a threat to the western islands because of the mountains on Hawaii Island.
"One is enhanced rainfall over the mountainous terrain releasing a tremendous amount of heat causing the air to rise and pressures to lower locally, leading to a deflection of the storm towards the island. The second impact is from higher wind speeds near between the mountains and the storm's center due to a funneling effect. This also leads to lower pressure nearer the island and again results in a deflection towards the island."
In addition, many years ago I was in a meeting with representatives from all the observatories and the team at UH's Mauna Kea Weather Center (MKWC - http://mkwc.ifa.hawaii.edu/). The Director of MKWC made a presentation at that meeting about the effects of the wind shadow downwind of Hawaii Island. IIRC, one of them was a potential drop in air pressure SW of the Big Island, which might cause hurricanes passing south of the Big Island to divert north towards Oahu and Kauai. I'll check whether the paper was published.
Interestingly, Hurricane Iniki did exactly that back in 1992. If that's the case, we have two mechanisms that cause storms to head towards the Big Island, which would protect the other islands, but another that creates a threat to the western islands because of the mountains on Hawaii Island.