Hawaiʻi County officials closely monitoring developing storm system

Hawaiʻi County officials are closely monitoring a developing storm system east-southeast of the Big Island that is likely to become a tropical cyclone within a matter of days.

The storm cluster — known as Invest 93C — as of about mid-afternoon Aug. 11 was located about 1,050 miles from Hawaiʻi Island, with forecasters listing a 90% chance that it will develop into a tropical cyclone within the next 48 hours.

Location or magnitude of potential impacts remain uncertain; however, Invest 93C is closer to Hawai‘i than cyclones typically arise, meaning impacts could occur with less warning than usual.

“We are closely tracking the development of this storm system and actively preparing for any hazards that could affect our island,” said Hawaiʻi County Mayor Kimo Alameda in a county release. “While the magnitude of impacts is uncertain at this time, the best way to keep you and your family safe is to prepare now and stay connected. Take the time to check on your home and follow official county channels, including our emergency alerts, and local news sources for updates.”

County officials urge the public to prepare for the possibility of severe — and even damaging — weather. Development of a tropical cyclone — which includes tropical depressions, tropical storms and hurricanes — could cause significant hazards as early as the evening of Aug. 14, including strong and high wind as well as heavy rainfall.

“While a tropical cyclone has not yet formed, environmental conditions are conducive for further development, and a tropical depression or storm is expected to form on Wednesday,” said information from the National Weather Service in Honolulu. “The disturbance is expected to move generally northwestward across the Central Pacific and toward the vicinity of the Hawaiian Islands later this week and into the weekend.”

Residents can limit damage and keep themselves safe by taking the following steps:

• Make a plan for how to shelter at home or move to safe shelter before a storm arrives. Discuss it with your family.
• Check around your home and trim vegetation that could be downed by wind and cause damage. Secure objects that could become airborne.
• Clear any debris that can block water from freely draining.
• Be ready for power outages.
• Make sure you have emergency food, water and medication for everyone in your household (including pets).
• Sign up online for Hawaiʻi County Civil Defense emergency alerts.

National Hurricane Center and Central Pacific Hurricane Center reported in a 2 a.m. Aug. 12 update that Invest 93C remained about 1,050 miles east-southeast of the Hawaiian Islands.

Associated shower and thunderstorm activity also remained disorganized; however, a tropical depression or storm is expected to form within the next day or so with environmental conditions continuing to favor further development while the system moves generally west-northwestward at 10 to 15 mph.

“Interests in the Hawaiian Islands should closely monitor the progress of this system,” said the update.

Forecasters joined the county in urging the public not to wait when it comes to making preparations.

“Prepare now,” the National Weather Service said. “Residents and visitors should continue to monitor the latest forecasts during the coming days and use this time to review hurricane preparedness plans and supplies. Do not focus on any single model forecast or projected track while the system remains in its early stages of development.”

Given the potential for development and expected movement of the system, several hazards could affect land and marine zones throughout the state, including:

• Fire weather: Concerns increase Friday as winds will begin to strengthen and a dry and stable air mass with low relative humidity in advance of the storm will likely lead to high wildfire potential.
• Strong and gusty winds: Winds could strengthen further Aug. 15, though the timing, direction and magnitude of the strongest winds remain highly dependent on the eventual track and intensity of the system. Even if the center of the system remains away from the islands, the north semicircle of the storm will likely produce damaging winds.
• Large, rough and possibly dangerous surf: The developing system is expected to generate a large easterly swell as it moves northwestward through the Central Pacific. Surf could build along east-facing shores from east to west as the system approaches, with warning-level surf of 15 feet or larger possible into the weekend.
• Heavy rainfall: This system could bring periods of heavy rainfall, particularly throughout east- and southeast-facing slopes. Orographic enhancement — the intensification of precipitation caused when large weather systems encounter physical land barriers such as mountains or steep terrain, forcing air upward and squeezing out extra moisture — could result in locally higher rainfall totals. If heavier rainfall persists over the same locations, flash flooding and rapidly rising streams are possible.

Meanwhile, another low pressure system located about midway between Hawaiʻi and west coast of Mexico is producing disorganized shower and thunderstorm activity, and while this disturbance has changed little in organization during the past few hours, any significant increase would result today in formation of a tropical depression.

The system — which is following behind Invest 93C — is forecast to move slowly westward or northwestward during the next couple of days and encounter less favorable environmental conditions late this week.

News reporter Nathan Christophel contributed to this story.