FIRST ALERT WEATHER DAY: Kona low brings the potential for flooding and heavy rain to parts of the state through Friday

A cut off low, is a weather woman’s woe! Kona lows are tricky to forecast because they are cut off from the jet stream and meander offshore for days at a time that could lead to several days of rain being tapped into deep tropical moisture to the south. Moist and humid conditions with southerly winds will persist into the weekend due to this Kona low located west of the islands. It is called “Kona” because of the south winds associated with them which are Kona winds. We received nearly 10 inches of rain on Maui and Hawaii Island today as a strong surge of moisture sat over the far eastern end of the state. The intensity is coming down but we will have to watch for individual heavy downpours into Friday but they should be less intense and not as much rain overall.

Showery conditions with periods of heavy rainfall are possible each day, which will keep the threat for flooding up. In addition to the rainfall potential, thunderstorms are possible, with a few potentially becoming strong tonight through Thursday. Conditions should begin to improve Saturday afternoon through early next week as drier air moves in and the trades return.

EARLIER TODAY: Showers embedded within deep layer cyclonic flow out of the south will stream across the area for at least the next couple of days. In the near term, showers and locally heavy rain is focused mainly over Maui County with another surge lifting out of the south toward Kauai. Outside of thunderstorms, rain rates have been limited to under 2 inches per hour with heavy rain bands demonstrating poor organization within weakly convergent low-level southerlies. This has led to widespread 24-hour rainfall amounts in the 1-4″ inch range, slightly less over Maui County. Given the lack of a front or larger scale focusing mechanism, showers will likely retain their present character going forward, namely coming in waves of loosely organized heavy rain bands. The present wave will continue lifting NE through Maui County while shortwave energy lifting toward Kauai is driving the next wave northward through the island. We are watching out for another wave that may impact Kauai into Friday. And will have to keep a close eye on the radar.

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Let’s talk surf: It has been messy with the south winds. A new small to moderate, medium period northwest (310-320 degree) swell has arrived at the buoys, resulting in a rise of surf along exposed north and west facing shores that will linger through Friday. A moderate, long period northwest swell (320 degree) will start to fill in Saturday, peak near advisory level Sunday and slow subside Monday. Expect choppy conditions along south facing shores due to persistent southerly winds mixed with small, long period south swells through the week. Less choppy conditions can be expected over the weekend as winds ease. Surf along east facing shores is expected to remain below average also due to persistent southerly winds. More typical choppy trade wind swell conditions will return early next week as trades return.

Wishing you blue skies and much aloha.

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