Moderate to breezy trade winds produced by strong high pressure far northwest of the state will back northeast ahead of approaching Tropical Storm Fausto into Tuesday. Shower activity will experience an uptick. As Fausto passes north of the Hawaiian Islands through Wednesday, diminishing winds for the islands could allow for sea breezes and heavy showers. A stable and drier breezy trade wind weather pattern will return across the state from Thursday onward as Fausto drifts westward away from the islands.
Satellite and radar imagery reveals low clouds and showers along windward and mauka locations with some showers making into leeward spots. As Tropical Storm Fausto passes north of the state the trades will be diminished and allow for the development of a sea breeze regime for the Big Island and possibly Maui County today. Backed northeast trade winds are more likely to persist ahead of the cyclone for Oahu and Kauai, which will keep a more typical windward and mauka shower pattern. With the more saturated air, heavy rain showers will be possible in the afternoon/evening for locations where the synoptic-scale winds weaken enough to give way to the sea breeze.
On Wednesday, another day of relatively weak winds will lead to further potential for sea breezes and heavy rain showers, this time including Oahu and Kauai.
Subtle shifts in the forecast track are still possible which would affect the specific island by island impacts from Fausto. We strongly encourage the public to pay close attention to this passing storm system as weather impacts over the Hawaiian Islands will evolve as Fausto gets closer.
High confidence Fausto impacts include: high surf warning for east facing shores through Wednesday. Lesser confidence impacts include: heavy rain threats through Wednesday.
By Wednesday night, Fausto continues on a west- northwest track and begins to gain distance from the islands, which will reintroduce moderate to breezy southeast to easterly winds into the forecast. From Thursday onward, a drier and more stable breezy trade wind pattern will return.
This morning, numerous low clouds and showers continue moving into north through east sections of all islands. Latest surface observations and satellite imagery show widespread MVFR ceilings and visibilities, with isolated IFR conditions. As a result, AIRMET Sierra remains in effect for mountain obscuration for windward sections of all islands. Expect some improvement throughout the day.
Meanwhile, as Tropical Storm Fausto draws closer (but remains north of the islands), trade winds will weaken and become more northerly today over the eastern end of the state, followed by Oahu and Kauai tonight. As light southeast to south winds develop and spread over the state from east to west, sea-breeze induced showers will increase during the afternoon and evening hours. MVFR or isolated IRF conditions will be possible in heavier showers, but otherwise, VFR flight conditions are expected to prevail. Aviation interests near the Hawaiian Islands should monitor updates to TC SIGMET Sierra, which covers Fausto, as the system passes north of the islands over the next few days.
Moderate to fresh NNE winds will be in place today as Hurricane Fausto enters the far northeast offshore waters. Winds will become more north and decrease tonight as Fausto moves through the northeast and northern offshore waters. As Fausto passes by, winds will be light and variable over the coastal waters, followed by south, then southeast immediately in its wake. As Fausto moves off to the northwest and high pressure builds to the north, east- northeast trades will build back in on Thursday then strengthen to fresh to locally strong levels on Friday into the weekend. A Small Craft Advisory (SCA) is now in effect for the windward waters due to the east swell through tonight.
Nearshore buoys on the eastern side of the islands have shown a considerable uptick with the medium and long period energy from Fausto. The surf is expected to peak this morning before dropping off Wednesday. A High Surf Warning for east facing shores is currently in effect through Wednesday afternoon. East shore surf will then trend back up Friday into the weekend due to a combination of rising trade wind swell and a new long period east swell generated by Hurricane Genevieve.
A series of south swells will keep south shore surf near the summertime average (5-6ft) through the week.
Surf along N shores could also see some brief increase as Fausto (or its remnants) pass near the region today and Wednesday, then return to typical flat to tiny levels late Wednesday into the weekend.
High Surf Warning until 6 PM HST Wednesday for Olomana-Maui Windward West-Kauai East-East Honolulu-Koolau Windward-Molokai Windward-Molokai Southeast-Windward Haleakala-Kipahulu-Big Island Southeast-Big Island East-Big Island North.
Small Craft Advisory until 6 AM HST Wednesday for Kauai Northwest Waters-Kauai Windward Waters-Oahu Windward Waters- Kaiwi Channel-Maui County Windward Waters-Pailolo Channel- Alenuihaha Channel-Big Island Windward Waters-Big Island Southeast Waters.
