Tropical Storm Olivia update: Sept. 10, 2018 at 5 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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On the forecast track, Olivia will be moving over the main Hawaiian Islands late Tuesday night into Wednesday.

Gradual weakening is forecast during the next 48 hours, but Olivia is expected to remain a tropical storm as it moves across the islands.

Olivia is moving toward the west near 10 mph. A continued west to west-southwest motion is expected for the next few days.

Maximum sustained winds are near 70 mph with higher gusts.

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

Watches and Warnings

A tropical storm warning is in effect for Oahu, Maui County including the islands of Maui, Molokai, Lanai, and Kahoolawe, and Hawaii County.

A tropical storm watch is in effect for Kauai and Niihau.

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

A tropical storm watch means that tropical storm conditions are possible in the watch area within 48 hours.

Interests on Kauai and Niihau should closely monitor the progress of Olivia.

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: 21.9N 149.7W


Maximum Sustained Winds: 70 MPH…110 KM/H
Present Movement: W OR 280 DEGREES AT 10 MPH…17 KM/H

Hazards affecting land

WIND: Tropical storm conditions are expected over Maui County and the Big Island starting late Tuesday or Tuesday night. Tropical storm conditions are expected over Oahu starting late Tuesday night or Wednesday morning. Tropical storm conditions are possible over Kauai County starting Wednesday afternoon.

RAINFALL: Olivia is expected to produce total rainfall accumulations of 10 to 15 inches. Isolated maximum amounts of 20 inches are possible, especially over windward sections of Maui County and the Big Island. This rainfall may produce life-threatening flash flooding.

SURF: Large swells generated by Olivia will spread from east to west across the Hawaiian Islands over the next couple of days. This will cause surf to build along exposed east facing shorelines as Olivia approaches. This surf may become damaging across parts of the state.

Air Force Reserve Hurricane Hunters indicated that Olivia was on a slow weakening trend as they departed the tropical cyclone earlier this afternoon. Bursts of convection have been occurring, but an  0058 UTC SSMI and 0155 UTC AMSU pass are showing disorganized banding mainly to the northeast of the center. This seems to indicate that Olivia is beginning to feel the effects of stronger shear. There was a fairly wide spread of satellite intensity estimates. However, used a blend of these along with the recent reconnaissance data to come up with the intensity estimate of 60 kt.

Olivia has been moving 280/9 over the last few hours. This slightly north-of-west motion may be due to the tropical cyclone beginning to feel the effects of the increasing shear. All reliable track guidance are unanimous in maintaining a westward motion overnight, then a slightly south of due west motion is expected to begin in 12 to 24 hours, as a very strong deep layer ridge develops west of the main Hawaiian Islands. Beyond 72 hours, an upper level low is expected to develop to the north of Olivia and drop south. This upper low is expected to impart a west-northwest motion on the tropical cyclone, and in fact the two systems may merge in four to five days, if enough of the low level circulation remains in the face of strong shear.

Shear is expected to increase over the next 24 to 48 hours as Olivia continues generally westward. Even though the sea surface temperatures warm to greater than 28C along the track beyond 48 hours, the shear should allow weakening to continue. The intensity guidance has been backing off on the weakening trend some in the 3 to 5 day time period, likely due to interaction with the upper low. Toward the end of the forecast period, Olivia may be starting to lose tropical characteristics. 


1. Resist the temptation to make comparisons between Hurricane Lane and Hurricane Olivia. Although Lane was a stronger tropical cyclone near the islands, it did not bring direct core impacts to the state. In some areas, Olivia could bring significantly worse impacts than were felt by Lane.

2. It is important to not focus on the exact forecast track and intensity when planning for Olivia. Persons on the main Hawaiian Islands should finish their preparations for direct impacts from this system starting as early as Tuesday night. Those impacts could include intense flooding rainfall, damaging winds, and large and dangerous surf.

3. Regardless of the exact track and intensity that Olivia takes as it approaches the islands, significant effects often extend far from the center. In particular, the mountainous terrain of Hawaii can produce localized areas of strongly enhanced wind gusts and rainfall, even well away from the tropical cyclone center.

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