textproduct: Honolulu

SYNOPSIS

A powerful kona storm will move in across the state this coming week into next weekend and will bring numerous impacts across the state. A combination of flash flooding, damaging winds, strong thunderstorms possibly severe at times, will threaten Hawaii from Wednesday through at least Saturday. The threat for flash flooding could begin as early as Tuesday over Kauai. While island by island impacts will be driven by where the bands of thunderstorms develop, leeward areas of the smaller islands currently seem to be the most favorable areas due to the kona winds.

DISCUSSION

Issued at 410 PM HST Sun Mar 8 2026

Currently at the surface, a storm force low is centered roughly 1400 miles northwest of Kauai. In the upper levels of the atmosphere, we are seeing a blocking pattern with a large high centered over the Aleutian Islands and an upper level low below it (northwest of the state). This blocking pattern has been producing numerous bands of thunderstorms over the Northwest Hawaiian Islands over the past few days. As the upper level high strengthens over the Aleutian Islands the next few days, this will allow the upper level low to shift closer to the state and will bring a prolonged period of heavy rainfall, strong to severe thunderstorms, and potentially damaging winds across the state.

Starting late Tuesday, southerly winds will begin to strengthen with an approaching upper level low. Latest global models and ensemble guidance is in good agreement with low level moisture increasing over Kauai throughout the day Tuesday and spreading towards Oahu Tuesday night into Wednesday. The threat for flash flooding will be increasing during this time, but it is expected to amplify during the day Wednesday as the threat for strong to severe thunderstorms increase over the western half of the state. 500 mb temps of -10C, surface dewpoints approaching 70F, PWs of around 1.5 to 1.7 inches, CAPE values of 1200-1700 J/kg (GFS model), 0-6 km bulk shear values of 30 knots and strong divergence aloft from an approaching jet streak, all provide the necessary ingredients to support strong to possibly severe thunderstorms. It is with these thunderstorms, where we could see intense rainfall rates, which can quickly lead to flash flooding and also damaging winds. While the western half of the state has the best chance for strong to severe thunderstorms on Wednesday, a threat for thunderstorms will exist all across the state. Currently a Hydrologic Outlook is in effect for the entire state due to the threat of flash flooding. This Hydrologic Outlook should be replaced by a Flood Watch for the entire state by Monday afternoon. While the threat for flash flooding and strong to severe thunderstorms tops the list for Wednesday, strong southerly winds will also develop, which could cause some gusty winds over our typical windward areas. Winds may reach advisory threshold, but confidence remains low at this time.

While our first wave of moisture begins to move further north on Thursday, strong southwest flow aloft and breezy southerly winds at the surface will continue to bring moisture across the state. Unstable conditions will continue to allow for the development of numerous showers and thunderstorms throughout the day Thursday, although global models are showing a slight decrease in coverage of showers and thunderstorms on Thursday. So some areas could see a slight break in action on Thursday.

From Friday onward, global models and its ensemble members have shifted with the latest guidance and is now showing the possibility of a widespread damaging wind event, as well as another round of strong to severe thunderstorms. Deep tropical moisture will also move in during this time with precipitable water values exceeding 2 inches. Deep tropical moisture, deep shear from the approaching upper level low, and a vigorous short- wave trough could lead to a very dangerous period of severe weather Friday into Saturday and possibly continuing into Sunday for select areas.

Now is the time to plan ahead for these significant statewide weather impacts. Some simple things to mitigate damages could be things such as cleaning your rain gutters and drains to prevent debris build up, secure your outdoor items to protect them from high winds. Lastly, please prepare for power outages and have extra nonperishable food, medication, water, etc... Be safe this week!

AVIATION

Issued at 410 PM HST Sun Mar 8 2026

Mostly VFR with areas of MVFR in showers and low clouds tonight and Monday. Areas of MVFR will be mainly on eastern and southern sections of each island. ESE surface winds will weaken slightly Monday. LLWS possible at PHOG/OGG into early this evening.

AIRMET Sierra for mtn obsc is in effect above 2000 feet for windward locations of Kauai, Oahu, and Maui.

AIRMET Tango in effect for mod turb blw 080 downwind slopes (south to northwest facing).

MARINE

Issued at 410 PM HST Sun Mar 8 2026 Strong high pressure far northeast of the state will maintain fresh to locally strong trade winds tonight, mainly over the eastern half of the state. The Small Craft Advisory (SCA) has been scaled back to include just the central and eastern waters through 6 am Monday. A front approaching from the west will begin to ease the trades further and shift them southeasterly on Monday, with the winds becoming southerly and increasing to fresh to strong speeds Tuesday through late this week. Heavy rain, thunderstorms, and rough seas are expected to accompany this storm system for the rest of this week and into the weekend.

Surf along east facing shores will gradually trend downward on Monday, then fall below normal levels Tuesday through late this week.

A series of west-northwest swells will keep some small surf in place along north and west facing shores during the next 7 days, but remain well below advisory levels. A small to moderate sized north swell is possible late this week.

Surf along south-facing shores will remain small, with the exception of areas exposed to trade wind swell wrap. Rough and choppy conditions will develop Tuesday and continue through late week as southerly winds increase in advance of a front. A series of small long-period south swells will also move through Monday through late this week.

HFO WATCHES/WARNINGS/ADVISORIES

Small Craft Advisory until 6 AM HST Monday for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Big Island Windward Waters-Kaiwi Channel-Maui County Leeward Waters-Maui County Windward Waters-Pailolo Channel.