textproduct: Honolulu

SYNOPSIS

Low pressure will draw deep tropical moisture over the state today. Waves of heavy rain capable of producing flash flooding are expected Wednesday through the end of the week. Southerly winds may become strong as well.

SHORT TERM UPDATE

Issued at 910 AM HST Tue Apr 7 2026

Forecast remains in reasonably good shape this morning with only cosemetic changes needed around Kauai where a band of moderate to locally heavy showers accompanies the mid-level wave that will advance through the area today. Showers have also anchored along Windward Haleakala on Maui early this morning courtesy as moderate ESE winds maxmize convergence and orographic lift there. The upper wave will gradually lift to the NE taking meaningful forcing with it. At the same time, weak but steady warm/moist advection will reduce stability and provide a background of modest forcing for ascent throughout the day. This likely explains why the band of showers presently entering the Kauai channel appears to be gradually building southward despite upper forcing already departing to the NE. These showers will reach Oahu around midday. Elsewhere and otherwise, isolated to scattered showers will likely be ubiquitous through the day, but decreasing dynamic forcing precludes a widespread heavy rainfall threat.

Strong mid-latitude wave then digs south well to the NW of the islands tonight pumping up heights and stability over the islands well into Wednesday. This will maintain the trend of isolated to scattered shower activity for at least the next 24 hours.

AVIATION

Issued at 910 AM HST Tue Apr 7 2026

Southeast winds have spread across the region, and a significant area of strong showers is progressing east from Kauai towards Oahu. These showers are forecast to get to PHJR/PHNL between noon and 2 PM HST. Additional showers are expected on all islands today and tonight. MVFR and isolated IFR conditions are likely in the stronger showers.

AIRMET Sierra is out for mountain obscuration on Kauai. This will likely be expanded to Oahu around noon.

MARINE

Southeasterly winds have spread across the islands with a front stalling to the west of the islands, and a surface right far to the north. Winds are expected to increase out of the south tomorrow and Thursday, as a low develops across the stalled front.

Showers, some locally heavy, will be possible through Friday as a result of the southerly winds bringing tropical moisture to the north over the islands. Thunderstorms have developed in the offshore waters to the northwest of Kauai, and thunderstorms are possible over the offshore waters through at least Friday.

A moderate long-period northwest swell will fill in today, giving more of a boost to north shore surf late today through Wednesday. A small, short- period north-northeast swell will fill in today before peaking Wednesday and subsiding Thursday. This overlap will make for some rough choppy conditions along north facing shores.

A slightly larger, long- period south swell, will increase today with a more noticeable increase tomorrow. Surf could reach advisory levels by Wednesday before slowly easing Thursday into the weekend. Strengthening southerly winds will make for rough and choppy surf by late next week.

East shore surf will remain small and below the seasonal average due to a lack of strong trade winds over and upstream of the islands, except for some wrap from the northerly swells.

HFO WATCHES/WARNINGS/ADVISORIES

Flood Watch from Wednesday morning through Friday afternoon for all Hawaii islands-

Winter Storm Watch from Wednesday morning through Friday afternoon for Big Island Summits.