textproduct: Honolulu

SYNOPSIS

A strong high pressure system far north of the Hawaiian Islands will continue to produce moderate to breezy trade winds through Monday with periods of showers favoring windward mountain areas in the overnight to early morning hours. Hurricane Fausto remains on track to pass near the Hawaiian Islands on Tuesday and Wednesday. The latest forecast for Fausto shows a weakening trend to tropical storm strength as it moves closer to the island chain. A drier and breezy trade wind weather pattern will return across the state from Thursday onward as Fausto drifts westward away from the Hawaiian Islands.

DISCUSSION

The satellite imagery this morning shows Hurricane Fausto moving into the Central Pacific basin. A few bands of clouds continue to drift into the islands on the trade winds this morning, producing brief showers mainly along windward mountain areas. Subsidence temperature inversion heights are lower, between 6,000 and 7,000 feet, as measured by the 2 AM HST (12Z) balloon soundings at Lihue and Hilo. These lower heights limit vertical cloud development and reduce shower activity in the short term.

East of the state Hurricane Fausto continues to march westward towards the Hawaiian Islands. Fausto remains on a high confidence track, keeping the center of the storm and the highest impacts passing north of the state. Additionally, the environment ahead of Fausto grows more unfavorable on approach to the islands and we expect Fausto to weaken into a tropical storm before arrival in the Hawaii region. That said, we remain cautious at this stage that even subtle southern shifts in the track or delayed weakening trends may still produce changes to our island by island impacts. We strongly encourage the public to pay close attention to this passing storm system as weather impacts over the Hawaiian Islands early next week will likely evolve over time.

High confidence Fausto impacts...High surf possibly above warning thresholds for east facing shores from Monday through Tuesday. Lesser confidence impacts include...strong winds to around 40 MPH may develop near and north of the low center and possible heavy rain threats from Tuesday through Wednesday.

No time like the present to review your family hurricane preparedness plans, and ensure every household has at least a 14 day supply of food and water available if needed during this years active hurricane season.

A drier and more stable breezy trade wind pattern will fill in across the state from Thursday onward as Fausto continues to journey westward away from the Hawaiian Islands.

AVIATION

Breezy trades through the rest of the weekend. Winds should trend down this evening. Low cigs and SHRA should primarily impact windward and mauka locations with some limited spillover to leeward areas. MVFR conds likely in heavier SHRA, otherwise VFR prevails.

AIRMET Sierra remains in effect for mtn obsc for windward portions of Kauai, Oahu, Molokai, Maui and the Big Island. Conds should improve in the early morning hours.

AIRMET Tango remains in effect for mod low- level turb downwind of island terrain. This AIRMET is likely to continue today.

MARINE

Fresh to locally strong trades will persist today then gradually shift to the NNE and diminish through the middle of the week in response to Hurricane Fausto passing north of the islands. The trades will then ramp back up to fresh and strong levels late this week into next weekend as Fausto continues off to the west- northwest away from the state while strong high pressure builds north of the islands. A Small Craft Advisory remains in effect for the windier waters around Maui and the Big Island through 6 PM this evening.

The current long-period south swell will hold steady at advisory levels through at lest the morning hours, then begin a slow decline late this afternoon through the end of the week. South shore surf will remain elevated above the summertime average through the middle of the week, before trending closer to or perhaps a bit below normal by next weekend. A High Surf Advisory is now in effect for south facing shores through 6 PM this evening.

Locally strong trade winds will continue to support rough surf above the seasonal average along east facing shores today. Trade wind swell will then decline due to diminishing trades tonight through the middle of the week. A long period swell from Hurricane Fausto will build today and Monday, then peak Tuesday into early Wednesday. This swell is forecast to produce advisory level surf along east facing shores as early as Monday, followed by potential for warning level surf as it peaks on Tuesday into early Wednesday. After a brief lull late Wednesday through Thursday, east shore surf will trend back up Friday into next weekend due to a combination of rising trade wind swell and a new long period east swell associated with Tropical Storm Genevieve moving in.

Surf along N shores remains flat to tiny today. Some increase is expected as Fausto or its remnants pass near the region Tuesday and Wednesday, with north shore surf returning to typical flat to tiny levels late Wednesday into next weekend.

HFO WATCHES/WARNINGS/ADVISORIES

High Surf Advisory until 6 PM HST this evening for all south facing shores.

Small Craft Advisory until 6 PM HST this evening for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters.