Flood Watch issued ahead of cold front

HONOLULU (KHON2) – Thunderstorms have been developing along the frontal boundary just west and north of Kauai during the day today with showers clipping Kauai throughout the afternoon.

Starting tonight as the frontal boundary slowly creeps towards Kauai, breezy southerly winds will be on the increase and will bring an increase of moisture.

In the upper levels of the atmosphere, we do have a shortwave trough digging towards the state, which should help ramp up the heavy showers and isolated thunderstorms late tonight.

At this time, the main instability seems to be north of the state, so the threat for severe thunderstorms will remain low.

Overall, this event looks to be a heavy rain event with gusty winds at times with any thunderstorms.

Latest forecast has 3 to 6 inches of rain with isolated pockets of up to 10 inches for Kauai early Sunday morning through Sunday night.

Due to the recent heavy rainfall, it will likely not take much to cause flooding issues on Kauai.

As the frontal boundary gradually progresses eastward on Sunday, showers will be on the increase for Oahu and parts of Maui County.

The frontal boundary should be weakening as it moves eastward, thus rainfall amounts should be less than on Kauai.

The main moisture band is expected to reach Oahu Sunday afternoon into the evening and over Maui County Sunday night into Monday.

We are currently monitoring the threat for flash flooding over on Oahu and Maui County and a Flood Watch will be possible for these islands late Sunday into Monday.

By the time the frontal boundary reaches the Big Island late Monday into Tuesday, rainfall amounts should be much less and is not expected to cause a flood threat on the Big Island at this time.

Our typical trade wind weather should return during the second half of next week.

Flood Watch from midnight HST tonight through late Sunday night for Niihau, Kauai,

Small Craft Advisory from 6 AM to 6 PM HST Sunday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel.