Powerful Kona Low Set To Bring Flooding Rainfall, Gusty Winds And Potential Blizzard Conditions To Hawaii By This Weekend

A powerful system called a Kona storm will bring flooding rainfall, strong winds, some severe thunderstorms, even mountain summit blizzard conditions to Hawaii into this weekend.

Flood and high wind watches are in effect throughout Hawaii. And, yes, winter alerts are posted for the summits of the Big Island above 12,000 feet elevation.

A potent low pressure system located some 1500 miles northwest of Kauai is pulling deep tropical moisture northeastward across the island chain.

Up to 6 inches of rain has already fallen in leeward (or southern) Kauai, and rivers rose on Tuesday in response to the heavy rainfall.

Forecast Timing And Threats

Unfortunately, this Kona low will remain relatively parked in place into the weekend, continuing to pump moisture into the state.

Heavy rain could arrive as soon as late Thursday on Kauai and Oahu before spreading through the rest of the state on Friday and lasting through Saturday or Sunday.

Major impacts are possible on every island at times through Sunday.

Flash flooding is the greatest threat from this storm, with most islands picking up several inches of additional rain. The heaviest rainfall totals should occur on the south- or southwest-facing coasts and mountain slopes. Some places could see more than a foot of additional rain.

A few severe thunderstorms are possible on Friday or Saturday with damaging winds and large hail. Unusually conducive conditions for Hawaii standards are expected to come together for severe weather.

The summits on the Big Island could also see significant winter impacts, including blowing snow and more than a foot of accumulation.

Hurricane force winds are possible over the coastal waters and choppy waters are a guarantee.

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What Is A Kona Low?

Kona lows are storm systems that set up to the west or northwest of the islands and draw up lots of moisture from the south, creating messy and sometimes dangerous conditions. They can bring widespread heavy rain to the islands with the threat of flash flooding, as well as damaging, gusty winds.

This is a phenomenon that occurs most often in January, although it can happen anytime between October and May.

This is a reversal from typical Hawaii weather.

The trade winds across Hawaii typically blow from the northeast. That means windward areas, generally the northeast sides of the islands, typically see more showers. On the Big Island, Hilo is the best example of this. They average a whopping 120.39 inches of rain a year.

But when a Kona storm moves in, it will bring winds from the southwest or “kona” side (or southwest side) of the islands. It's these storms that soak normally drier locations in the islands, including Honolulu and the Kona coast of the Big Island. Honolulu averages only 16.41 inches of rain a year.