Tropical Storm Olivia update: Sept. 12, 2018 at 2 p.m. HST


EDITOR’S NOTE: This is an archive post of KHON2’s ongoing Hurricane Olivia coverage. Click here to view the most recent update.

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View Hawaii flood maps at this link.

At 2:00 p.m., the center of Tropical Storm Olivia was located about 45 miles south of Oahu.

Olivia has accelerated and is moving toward the west near 20 mph.

A turn toward the west-southwest will occur this evening, with a similar west-southwest motion expected through Friday.

Maximum sustained winds are near 40 mph with higher gusts. Gradual weakening is forecast during the next 48 hours.

Tropical-storm-force winds extend outward up to 90 miles from the center.

The center of Tropical Storm Olivia made a historic landfall at about 9:10 a.m., near Kahakuloa on the windward coast of the West Maui Mountains. This is about 10 miles northwest of Kahului. This is the first tropical storm to make landfall in recorded history. Records of storms go back to the 1950s.

Olivia then made a second landfall at about 9:54 a.m. on the northeast coast of Lanai, about 6 miles north-northeast of Lanai City.

Watches and Warnings

A Tropical Storm Warning is in effect for Oahu, Maui, Molokai, Lanai, and Kahoolawe. 

The Tropical Storm Warning for Kauai, Niihau and Hawaii Island was discontinued.

Interests in the Northwest Hawaiian Islands should monitor the progress of Olivia.

A tropical storm warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours.

Flash flood warnings


The National Weather Service in Honolulu has issued a flash flood warning for the entire island of Maui until 4:15 p.m.

At 1:11 p.m., radar showed heavy rain continuing over portions of Maui. The highest rates were estimated to be 2 to 3 inches per hour over the West Maui Mountains and 1 to 2 inches per hour over the southeastern slope of Haleakala. Waikoloa Road and Ulaino Road remain closed near Hana. Low water crossings along Piilani Highway from Waiopae to Kipahulu are at risk of being closed by flooding.


The flash flood warning was extended for the island of Molokai until 3:15 p.m.

At 11:54 a.m., radar showed that heavy rain has moved over most of Molokai as the center of Tropical Storm Olivia passes to the south of the island. The gage in Halawa Stream showed a recent increase in water level of 3 feet. Police on Molokai reported that water was flowing across Highway 450 near Kawela.

Keep in mind, changes will occur in forecast track and intensity as the storm gets closer. Download our KHON2 News mobile app and turn on the push alert notifications to get the very latest.

Location: 20.6N 158.1W


Maximum Sustained Winds: 40 MPH…65 KM/H

Present Movement: W OR 260 DEGREES AT 20 MPH…30 KM/H

Hazards affecting land

WIND: Tropical storm conditions are ongoing in portions of Maui County. Tropical storm conditions are expected over Oahu this afternoon. Remember that wind gusts can be much stronger near higher terrain, and in the upper floors of high-rise buildings. Winds can also be especially gusty through gaps between mountains and where winds blow downslope.

RAINFALL: Showers will continue to increase over the main Hawaiian Islands today. Olivia is expected to produce total rainfall accumulations of 5 to 10 inches in some areas, with isolated maximum amounts of 15 inches possible, especially in higher terrain. This rainfall may produce life-threatening flash flooding. Nearly 9 inches of rain has already fallen over parts of Maui.

SURF: Large swells generated by Olivia will impact the main Hawaiian Islands into tonight. This will result in dangerously high and potentially damaging surf, mainly along exposed east facing shores.

The partially exposed low-level center of Olivia made landfall over northwest Maui at approximately 1910 UTC (910 AM HST), then exited Maui to the west to make another landfall on the island of Lanai around 1954 UTC (954 AM HST). Deep convection continues to pulse to the north and northeast of the center of Olivia, as the system remains under strong westerly vertical wind shear of 30 kt. Subjective Dvorak current intensity estimates ranged from 2.0/30 kt from SAB and JTWC to 2.5/35 kt at HFO. However, WSR-88D velocity data from Molokai has been consistently showing velocities of 50 kt to the north of the center around 5,000 ft, and there has been little change in the satellite presentation since last night. Thus, the initial intensity will be maintained at 40 kt. 

The motion has become west (265 degrees) and increased to a short-term average of 13 kt. As strong wind shear persists and Olivia interacts with the high terrain of Molokai and Maui, the system is expected to weaken, which will likely maintain an erratic motion through the afternoon. However, a turn toward the west-southwest is expected as the weaker system becomes increasingly steered by the low-level trade wind flow. This motion will continue into Friday, followed by a turn toward west or west-northwest thereafter as Olivia interacts with the upper low responsible for the wind shear. The forecast track was nudged slightly north of the last advisory and lies near GFEX and TVCE in the middle of a tightly clustered guidance envelope during the initial 48 hours, with increasing spread beyond. Olivia is forecast to become a tropical depression by Thursday and a post-tropical remnant low on Friday. This could occur sooner if Olivia is significantly weakened by island terrain. The intensity forecast closely follows SHIPS, which is slightly more aggressive in the weakening of Olivia than the other statistical and dynamical guidance.

Key Messages:

1. Flooding rainfall, high surf, and damaging winds are expected in the warning area. Significant impacts can occur well away from the center, especially when considering that the mountainous terrain of Hawaii can produce localized areas of strongly enhanced wind gusts and rainfall.

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