textproduct: Honolulu

SYNOPSIS

The remnants of Fausto will continue to pass Hawaii to the north resulting in light winds and muggy conditions. Trades will quickly fill in tonight through early next week, becoming breezy to locally strong Friday into Saturday. Trades will ease to more typically breezy speeds early next week as the high weakens.

DISCUSSION

The remnant low of Fausto, roughly 160 miles north of Oahu, will continue to weaken while tracking west- northwest, north of the state. This low will continue keep light and variable winds across the state through tonight. A trailing cloud band with embedded light to locally heavy showers is currently moving from east to west across the Big Island. Elsewhere, the combination of light northerly winds and seabreezes is producing cloudy conditions with some embedded light showers along mountain slopes and over interior areas. Rainfall rates are less than .1 inches per hour with higher rates of .5 inches in some of the brief heavy showers. The band of scattered clouds and enhanced moisture will continue to move westward across the rest of the state tonight and through the morning hours Thursday, increasing chances of showers. So far the small areas of heavy showers have been brief and not causing any flooding concerns.

Thursday, a strong high will develop far northeast of the state allowing breezy to locally strong winds to return by Friday and Saturday. Expect a more typical tradewind pattern with showers focused mainly along windward and mauka areas. Drier air will also filter allowing dewpoints to dip below 70 degrees by Friday. Downslope winds under this drier and stable airmass could meet or exceed wind advisory criteria. We will continue to monitor all available guidance and observations.

Sunday into early next week trades will weaken to moderate to locally breezy levels as Hurricane Genevieve tracks far northeast of the state, disrupting the trade wind flow.

AVIATION

Variable afternoon winds will be replaced by east to southeast flow overnight as the remnants of former tropical cyclone Fausto pass north of Kauai. The east-southeast winds will spread over the Big Island late this afternoon and push a shallow band of moisture onto windward slopes. This moisture will produce MVFR ceilings on windward Big Island, where AIRMET Sierra for mountain obscuration may be needed through the evening. AIRMET Sierra remains posted for northern slopes of Maui and Molokai due to stubborn low ceilings in the high humidity conditions south of Fausto. Some improvement is expected late this afternoon, but the AIRMET may be needed overnight for windward slopes as the moisture nearing the Big Island spreads westward. On Oahu and Kauai, ceilings over terrain should remain less extensive through most of the night.

Easterly trade winds will develop over the entire island chain Thursday. Deeper moisture over the western end of the state may produce widespread ceilings over windward slopes of Kauai and Oahu. VFR will prevail leeward.

MARINE

Variable to light northerly winds today in response to Post- Tropical Cyclone Fausto passing north of the islands. Trades gradually build from east to west in its wake. Moderate to fresh ESE trades become strong Friday through the weekend, eventually warranting a Small Craft Advisory for winds, potentially as early as tomorrow for the windier waters of Maui County and the Big Island.

Nearshore PacIOOS buoys indicate continued decline in easterly swell. The High Surf Advisory was cancelled earlier today. A small bump in short to medium period NE and N will arrive as Post- Trop Cyclone Fausto advances westward north of the islands providing small surf along N facing shores. Flat to tiny surf then returns by Thursday. Surf along E shores will trend up Thursday night into the weekend due to a combination of building short period trade wind swell and renewed medium to long period E swell, this time emanating from Hurricane Genevieve in the E Pac.

A medium period S swell building today and tonight will push S shore surf toward the summer average (5-6ft) for Thursday. Surf then fades gradually through the weekend while a mix of small S swells maintains surf slightly below the seasonal average.

FIRE WEATHER

Trade winds are expected to strengthen from east to west across the state Thursday becoming breezy to locally strong Friday into Saturday. As the winds become strong late Friday into Saturday, a drier more stable airmass will filter in, increasing the potential for locally strong downsloping winds. While KBDI will remain below the critical thresholds there could still be some fire weather concerns.

HFO WATCHES/WARNINGS/ADVISORIES

Small Craft Advisory until 6 AM HST Saturday for Pailolo Channel- Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters.