A Look Back at Hurricanes to Impact Hawaii
With Tropical Storm Calvin impacting Hawaii this week, I thought it would be interesting to look at history to see just how common significant tropical cyclones affect the island and examine the atmospheric and oceanic conditions that favored impacts to Hawaii. We’ll start by looking at the most significant tropical cyclone to impact Hawaii in the island’s modern history: Hurricane Iniki of 1992 (Figure 1) [1].
Iniki struck the island of Kaua’i on September 11, 1992, as a category 4 hurricane [1]. Like Calvin, Iniki developed during an El Niño event in the equatorial Pacific, though on the tail end of the El Niño rather than near the start as with Calvin [2, 6]. Perhaps in part due to the timings with the phase of ENSO, the central Pacific was much warmer than normal at the time of Iniki’s formation compared to the tropical central Pacific this year [3, 4]. In addition, unlike most storms to impact Hawaii, Iniki passed the south of Hawaii before curving north due to an incoming area of low pressure [5]. This meant that the storm had ample time over the substantially warmer waters to the south than if it had come in from the east of the island. In addition, the storm accelerated upon turning to the north which meant that any impact due to cooler waters was dampened by the storm’s rapid forward motion [5]. Iniki remains the costliest storm in Hawaiian history, with overall losses estimated at 3 billion USD adjusted for inflation [6].
A more recent example is Hurricane Lane in 2018 [7]. The storm peaked as a category 5 hurricane with winds of 160 miles per hour just 320 miles southeast of South Point, Hawaii [9, 10]. At this point, Lane was forecast to come uncomfortably close to the capital, Honolulu, as a powerful hurricane, prompting the issuance of hurricane watches and warnings for the entire stretch of the island [7, 9]. Like Iniki, the storm formed during an El Niño event and traversed the Pacific Ocean to the south of Hawaii before curving north (see Figure 5) [10]. However, and fortunately for Hawaii, strong upper-level winds caused the storm to weaken significantly before turning to the west and missing the island [10]. Nonetheless, Lane was still notorious for dumping over 50 inches of rain in parts of Hawaii, which is the most rainfall from a single tropical cyclone in the United States except for Hurricane Harvey in 2017 [8].
Our analysis of Hurricanes Iniki and Lane show some similarities between the environmental setups that increased the probability of a tropical cyclones heading towards Hawaii. First was an El Niño event that resulted in warmer-than-normal SSTs in the central tropical Pacific [5, 9]. Second was a track initially to the south of the island, where upper-level winds are usually weak and SSTs sufficiently warm to support a powerful hurricane [5, 9]. Third was an eventual turn to the north that allowed the systems to remain over warmer water longer than if they had tracked in from the east [5, 9]. However, not all storms to impact the island as hurricanes follow this paradigm. Take Hurricane Lester in August of 2016 [11]. While the storm only brushed Hawaii without making a direct landfall, it was a hurricane within a close vicinity of the island [11]. In contrast to Hurricanes Iniki and Lane, Lester approached the island from the east rather than the south [11]. This was again made possible by the central tropical Pacific to the east of Hawaii being 1 to 2 degrees Celsius warmer than normal during August of 2016, although the equatorial Pacific was not experiencing El Niño conditions at that time [3, 11].
From Figure 3, we can reasonably infer that had Hurricane Lester been located only a little further south on its approach to Hawaii, the island could have easily sustained a category 1 or 2 hurricane landfall. Perhaps there is some element of luck that explains the few direct landfalls by hurricanes in Hawaii’s history.
While every tropical cyclone is unique, the analysis of Hurricanes Iniki, Lane, and Lester at least give us an idea of the factors that can lead to a significant tropical cyclone impact for the island of Hawaii. These historical events also remind us that, even in a place like Hawaii where a direct landfall from a tropical cyclone is uncommon, vulnerable communities can be caught off guard and left to cope with the impacts at a moment’s notice. Here at Kinetic Analysis Corporation, we provide you with accurate, near real-time information about a tropical cyclone as it unfolds. We do this by synthesizing information from a variety of sources and translating the meteorological hazards into easily digestible impacts information. This includes populations affected by tropical storm/hurricane force winds and storm surge, economic loss and structural damage estimates, and shutdown times for facilities such as airports and seaports. All of this information is available in our state-of-the-art web app, KinetiCast™. Now for a limited time, we are offering the next 20 people who sign up to use KinetiCast™ a license for $25/month. If you would like more information, please reach out to aagastra@kinanco.com.
References
1. https://www.foxweather.com/learn/hurricane-iniki-hawaii
2. https://blog.ucsusa.org/roberto-mera/hawaiis-hurricanes-el-nino-and-climate-change-622/
3. https://climate.nasa.gov/climate_resources/185/sea-surface-temperature-anomaly-timeline-1982-2017/
4. https://www.tropicaltidbits.com/analysis/ocean/
5. https://www.weather.gov/media/publications/assessments/iniki1.pdf
6. https://weather.com/news/news/remembering-hurricane-iniki-20120911
7. https://abcnews.go.com/US/hurricane-lane-strengthens-category-storm-closes-hawaii/story?id=57327831
8. https://weather.com/storms/hurricane/news/2018-08-28-lane-hawaii-tropical-cyclone-rainfall-record-one-year-after-harvey
9. https://www.nhc.noaa.gov/archive/2018/LANE_graphics.php
10. https://www.nhc.noaa.gov/data/tcr/EP142018_Lane.pdf
11. https://www.nhc.noaa.gov/data/tcr/EP132016_Lester.pdf
12. https://www.cnn.com/2016/08/30/weather/tropical-storms-hurricanes-carolina-hawaii/index.html