A State of Emergency is underway in Hawaii as the island state prepares for the most severe hurricane to impact the island chain since Category 4 Hurricane Iniki made landfall over Kauai in September 1992. Iniki devastated parts of Hawaii, hitting Kauai especially hard and causing $3.1 billion in damage as well as resulting in six deaths according to the National Hurricane Center. Hurricane Lane, a major hurricane, unfortunately has the potential to rival this devastation.

Hurricanes are very unusual in the Central Pacific, let alone hurricanes of Lane’s caliber. Hawaii is a small island chain in a very big ocean. Hurricanes usually originate in the tropics and travel towards the west-northwest in the Northern Hemisphere. Typically, their origination is from thunderstorms or weak low pressure systems that form over land. The closest landmass to Hawaii is the central California coastline, roughly 2,282 miles away. Mexico, where many tropical cyclones originate, is over 2,500 miles away. Hawaii is essentially  minuscule from that far of a trajectory. Additionally, cooler waters surrounding the islands usually protect them from the strongest storms. Sea surface temperatures near Hawaii are running more than one degree Fahrenheit above normal, helping sustain Lane in its approach.

As of 9:00 Wednesday morning HST, the center of Major Hurricane Lane was located roughly 200 mi southwest of Kailua-Kona, Big Island,  slowly crawling northwest at 7 mph. Lane’s outermost bands extended over 300 miles from its center and have already began sweeping across Big Island, prompting flash flooding along the eastern slopes as nearly a foot of rain has already fallen. Lane’s maximum sustained winds were rated at 130 mph, making it a Category 4 Hurricane. Tropical Storm force winds of at least 39 mph were confined well to the south of Big Island.

Major Hurricane Lane is expected to bring up to four days of torrential rain and roof-shearing, tree-snapping, power line- toppling winds to most of Hawaii. The storm is expected to crawl slowly northward toward the islands before making a sudden westward turn early Saturday. It is uncertain whether Lane will make landfall on one or more of the islands. If Lane makes landfall, it will most likely be Friday afternoon, and the storm would weaken at an accelerated pace as it interacts with the mountainous topography. If Lane does not make landfall it will weaken at a slower rate, but localized impacts will not be as extreme.

As Lane continues northwestward, the storm will descend into an increasingly hostile environment for hurricanes.  Lane is already ensnared by a small region of wind shear along its northeastern flank. Wind shear acts to tear apart a tropical cyclone’s warm core. Through the weekend. a strip of wind shear will elongate along and to the north of the islands as the circulation of an upper-level ridge and upper-level trough converge. This perpetual influence of shear will hinder Lane’s organization. Additionally, Lane will encounter cooler sea surface temperatures as the hurricane approaches Hawaii, reducing available energy for the storm.

Hurricane Lane will be picked up along or just south of the islands by the circulation of high pressure to the north between Friday afternoon and early Saturday morning, causing the hurricane to slowly weaken and devolve into a Tropical Storm. However, this weakening of Lane will not eliminate the storm’ s potent hazards. Several days of strong winds and torrential rain will have done a number on the islands. Winds may diminish, but the heaviest rain will shift to the northeastern quadrant, so torrential rains and flooding will continue to overwhelm the islands throughout the storms’ weakening process.




The wind and intensity forecast are highly contingent upon the ultimate track. There is unusually low consensus among the global and hurricane models. Remarkably, the spread among the models has gotten worse as the storm nears Hawaii. This morning, most models  depicted the anticipated westward turn roughly 100 mi south of Honolulu. However, models have further diverged this afternoon. The spaghetti plot below demonstrates this uncertainty.

18 UTC (2pm EDT) Plots of Hurricane Lane tracks for the next five days from various global and hurricane models. Plot courtesy of Tropical Tidbits.

It’s possible that Lane’s outer bands just brush Hawaii before the storm goes out to the open ocean. Alternatively, the storm could make landfall on Hawaii before turning west and skirting the shores of the islands. Most of the Euro’s 51 ensemle members keep Lane well offshore to the south, and only a few of the GFS Ensemble’s 20 members make landfall. Therefore, a westward track just south of the islands is favored at this time, but changes are likely.




The official  Central Pacific Hurricane Center forecast track is provided below. The cone gives the range of probable paths, so the cone center does not necessarily represent the ultimate track of the storm. Given an offshore track in the proximity of the islands, the heaviest of the rain will fall along eastern facing mountain slopes. Rain will be enhanced by orographic lift, when winds blow up a mountain and quicken the cooling and condensation process. 10 to 20 inches of rain are possible in low-lying areas, with over 30 inches possible in the higher terrain of southeastern slopes of southern Big Island, Maui, Miloka’i, and O’ahu. Rainfall will likely be lower over Kauai and Ni’ihau.

That the heaviest rain will fall over southeastern slopes consequentially implies the most powerful wind gusts will generally effect west and northwest facing slopes. Much of the moisture contained in the air will precipitate out as it blows over the highest mountain peaks. Cooler and drier than the surrounding air, winds will accelerate down mountains. Powerful wind gusts will also develop in the vicinity of the heaviest downpours  Sustained tropical storm force winds will most likely impact the eastern half of Big Island and the southern coasts of the other islands, as these areas will be closer to the eye. Sustained hurricane-force winds are unlikely unless Lane makes landfall, but hurricane force gusts of at least 74 mph are possible in these same areas. Tornadoes are an additional threat, especially in low-lying areas along west and northwest facing slopes .

Extreme to catastrophic damage is a likely outcome from Lane. Raging flood-waters will inundate low-lying and coastal areas susceptible to storm surge. Creeks, streams, and canyons will become raging rivers. Rivers will overflow their banks. Water will plow down mountainsides, resulting in widespread mudslides and overwhelming flooding in valleys, Power-outages and impassable roads will complicate emergency responses. These are definite impacts regardless of the storm’s ultimate track, not poetic over exaggerations. This storm is extremely serious.

Residents are urged to prepare for flooding and act immediately if evacuation orders are issued. Be sure to have abundant water, non-perishable food, flashlights, and batteries for radio on hand. All emergency preparations should consider impacts from tornadoes. If a tornado strikes, seek shelter in a room without windows in the lowest level of the structure.

The situation will continue to evolve. WeatherOptics will provide updates as new information becomes available.



Author

Josh is a lifelong nature and weather enthusiast as well as the Head Meteorologist at WeatherOptics. He began regularly forecasting for New Jersey, Long Island and New York City in 2014 on social media, contributing to community pages such as SBU Weather. He holds degrees in Physics and in Atmospheric and Oceanic Sciences from Stony Brook University, from which he graduated in 2018. In the Fall of 2018 Josh will start graduate school for his M.S. in Marine and Atmospheric Sciences at Stony Brook, continuing his research on approaches to non-convective wind gust forecasting.

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