Hawaii Braces for Days of Torrential Rain as a New Storm Approaches

A newly formed tropical rainstorm is heading to Hawaii, delivering another threat of flooding and mudslides during what has already been an extremely active tropical weather season for the islands. Here is what you need to know about the latest threat.

Hawaii's Big Island in Line of Fire for New Tropical Rainstorm

A slowly-moving tropical rainstorm has come together roughly 700 miles to the southeast of Hawaii's Big Island. The latest feature is forecast to unleash flooding rainfall and mudslides for portions of the state beginning on Wednesday.

Forecasters identified the cluster of rain showers and thunderstorms early in the week. This disturbance is expected to continue to move to the west throughout the week, potentially evolving into a tropical depression or tropical storm.

The next name on the list of designations in the central Pacific is Nolo.

The latest forecast models suggest that the forward speed of this storm will begin to slow as it approaches Hawaii from the south. This slowdown will funnel a plume of tropical moisture toward the islands, resulting in heavy rain capable of triggering flash flooding, mudslides, and road washouts. The degree of impacts will depend on how much the storm stalls.

Forecast Rain and Wind Impacts

Widespread rainfall amounts of 1 to 2 inches are expected for a zone from northern Kauai and into the western edge of the Big Island. Higher totals of 2 to 4 inches are likely across the northern shores of Moloka'i to the Big Island. The Big Island will bear the brunt of this storm's impacts, with rainfall of 4 to 8 inches over the course of the event. The area in and around Hilo could see up to 12 to 18 inches.

The current speed of the storm is signaling roughly three days of heavy rain for the Big Island. However, this timeline could be extended to five to six days if the rainstorm stalls near the island. The mountainous terrain could pick up rainfall measured in feet over the duration of the storm from Wednesday through next Monday.

While the Big Island is bracing for the worst of the impacts, flooding downpours are also possible in Maui and Oahu. Like the Big Island, the highest threat of flooding and mudslides will be across the steep terrain of these islands.

Although Kauai is not expected to be in the primary impact zone, any bit of rain and wind could exacerbate the recovery efforts still happening after Hurricane Lala's strike a few weeks ago.

Winds are forecast to gust to between 40 and 60 mph across Hawaii and Maui counties through Monday. The windy conditions paired with the saturated soil from the steady stream of moisture will naturally increase the risk of downed trees and power lines.

It has already been a historically busy tropical weather season in the Pacific. Hawaii has seen two hurricanes skirt by over the last two months, a notable occurrence in a part of the Pacific that is typically immune to major tropical weather impacts.

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