Norman to batter Hawaii with dangerous seas later this week

By Kristina Pydynowski, AccuWeather senior meteorologist

September 03, 2018, 10:43:33 PM EDT

Dangerous surf will be stirred around the Hawaiian Islands during the mid- to latter part of this week, even though Norman will no longer be a major hurricane at that time, and may only be a tropical storm.

Norman is tracking toward the Hawaiian Islands but is not anticipated to be a repeat of Hurricane Lane and its inundation of torrential rain.

Lane approached Hawaii from the south and unloaded the most amount of rain from a tropical cyclone in Hawaii's history.

Prior to this year, a Category 5 hurricane had never come as close to Hawaii as Lane did.

While currently a Category 1 hurricane, Norman is expected to be a tropical storm when it tracks north of the islands later this week.

"Norman will slowly weaken as it encounters gradually colder water and slightly more wind shear over the next few days,” said AccuWeather Senior Meteorologist Rob Miller.

Wind shear is the changing of speed and direction of winds at different layers of the atmosphere. Strong wind shear can shred apart mature tropical storms or hurricanes.

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A track to the north will also keep the heaviest rain of Norman away from the islands.

If Norman tracks close enough, it may increase showers across windward locations late this week. Prior to that, sinking air (which dries out the atmosphere) ahead of the storm can lead to most of the islands being rain-free at midweek.

Regardless of the exact track, Norman is expected to stir another round of dangerous seas around Hawaii.

Seas that turned choppy this weekend as Miriam passed by will further increase Wednesday into Friday at the east- and north-facing beaches.

Conditions may become too dangerous for swimmers and surfers. Boaters may be forced to remain in port these days.

There can also be incidents of coastal flooding and beach erosion.

Download the free AccuWeather app for the latest forecast and advisories related to Norman.

On the heels of Norman, strengthening Olivia is expected to curve to the northwest well before reaching Hawaii. However, swells from the future major hurricane can keep seas rough next weekend.

Residents of Hawaii need to remain vigilant for additional threats from tropical storms and hurricanes through autumn, due to a developing El Niño.

"Because El Niño is a plume of warmer-than-average waters over the tropical Pacific Ocean, the warm water can sustain more hurricanes than average over the eastern and central Pacific, cause them to be stronger in nature and allow them to retain strength for a longer period of time as they approach Hawaii," according to AccuWeather Senior Meteorologist Alex Sosnowski.

Regardless of any tropical threat, the developing El Niño should lead to wetter-than-normal weather in Hawaii through September and October, according to AccuWeather Senior Meteorologist Brett Anderson.

"There should be a turn to drier weather close to winter, as is typical during an El Niño," Anderson said.

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