textproduct: Honolulu

SYNOPSIS

A weak upper low combined with a tropical wave passing south of the islands will ramp up humidity levels and keep periods of wet weather in the forecast through Friday. Drier trends are forecast for the weekend.

SHORT TERM UPDATE

The latest satellite imagery this evening shows an area of thunderstorms near a tropical disturbance roughly 800 miles southeast of the Big Island, and a weakening cold front roughly 650 miles northwest of Kauai continues to slowly approach the islands. Water vapor imagery shows a weak upper low just west of the islands, spreading divergent high level cirrus clouds across the state. This upper low will in the short term continue to weaken and lift the trade wind temperature inversion, allowing for continued periods of passing showers.

A tropical wave passing south of the islands will ramp up humidity levels across the state and keep periods of wet weather in the forecast for Friday. Drier trends are forecast for the weekend.

A few updates to the forecast grids this evening. Lowered sustained wind speeds over Oahu and Molokai for the next few days. Removed isolated thunderstorms for the Big Island tonight as there will likely not be a sufficient trigger for thunderstorm development.

PREV DISCUSSION

Issued at 351 PM HST Thu Nov 5 2026

The 18Z surface analysis shows a ridge of high pressure north of the state driving breezy trades across the island chain this afternoon and a trough to the southeast of the Big Island. Radar imagery shows isolated light to moderate showers in windward areas.

The tropical disturbance southeast of the islands remains an elongated trough for the time being. The latest ASCAT pass from 1928Z indicates winds remain less than 25 kts north of 20N latitude, which is a reduction from the last couple passes. While some uptick in winds is likely near the typically favored terrain features this evening, confidence for a larger scale increase of wind has decreased. Therefore, held off on Wind Advisories for now.

Satellite derived pwats from CIMSS depicts deeper moisture approaching the Big Island from the southeast late this afternoon. By late tonight and Friday, pwats should exceed 2 inches across the Big Island. A sharp uptick in shower development is expected in windward and mauka areas, possibly leeward as well. Isolated thunderstorms capable of producing heavy downpours cannot be ruled out for Big Island through Friday as the deep moisture erodes inversion heights, allowing for some terrain induced convection to occur. Total rainfall totals of 2 to 3 inches appear likely for windward Big Island with some areas possibly approaching 4.

After the system passes west of the state Saturday into Sunday, a much drier airmass and lower inversion heights will filter in from the east into next week. Winds will ease to more typical levels. The drier airmass and lower inversion heights will also limit shower coverage to mainly windward areas.

AVIATION

Issued at 351 PM HST Thu Nov 5 2026 Breezy trades will continue for the next few days. An area of enhanced moisture moving in from the east will affect windward portions of the Big Island and to a lesser extent, the rest of the islands tonight into tomorrow morning, bringing more widespread MVFR with pockets of IFR for windward areas. Isolated showers with brief MVFR conditions could also spill over to leeward areas, mostly during the evening and early morning hours.

AIRMET Sierra is in effect for mtn obsc for windward portions of Kauai and Oahu due to persistent showers. Conds should become worse later tonight as more moisture moves in and the AIRMET could expand to include more islands.

AIRMET Tango remains in effect for mod turb lee of terrain and should remain in effect for next few days.

MARINE

Issued at 351 PM HST Thu Nov 5 2026 Fresh to strong trade winds with periods of near gales will prevail through the weekend as high pressure persists north of the state. A Small Craft Advisory (SCA) remains in place for all Hawaiian Waters for a combination of winds and elevated seas. The SCA was extended through Saturday night and will likely remain in place through at least Sunday night as a disturbance or tropical cyclone passing a couple hundred miles to the south keeps the local pressure gradient tight. Winds are expected to ease slightly as the ridge to our north erodes and the potential tropical cyclone moves away to the southwest. The SCA will likely be trimmed back to the typical windy waters around Big Island and Maui sometime Monday or Tuesday.

A long-period north-northwest (325 to 345 degree) swell will peak through evening and produce surf well above High Surf Advisory thresholds along exposed north and west facing shores from Kauai to Maui. Recent observations from NOAA buoy 51001 northwest of Kauai showed the swell at around 9 feet at 16 seconds, and swell energy at the PacIOOS Waimea buoy continues to slowly rise this afternoon. Surf will decline below advisory thresholds late Friday as the north-northwest swell declines. Reinforcing medium period energy out of the north-northwest (330 to 340 degree) should arrive late Saturday into Sunday. Surf could approach advisory thresholds during its peak early Sunday morning. Another large northwest to north-northwest swell is Wednesday or Thursday of next week.

A small south-southwest swell is expected to fill in overnight. This small bump should peak Friday with waves slightly above average for this time of year Friday into Saturday along south facing shores. Surf along east-facing shores will stay elevated and choppy through much of the week due to the strong trades. Select northeast exposures should see long-period energy from the large north-northwest swell today through tonight.

FIRE WEATHER

Issued at 351 PM HST Thu Nov 5 2026

Persistent rainfall will continue to limit the widespread availability of receptive fuels. Breezy and gusty winds will continue during the next several days, generating moderate fire weather conditions. Isolated thunderstorms will be possible for Big Island tonight through Friday. The inversion near Big Island will range from 8000 to 10000 ft through Friday.

HFO WATCHES/WARNINGS/ADVISORIES

High Surf Advisory until 6 PM HST Friday for north and west facing shores.

Small Craft Advisory until 6 AM HST Sunday for all Hawaiian coastal waters and channels.