Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
945 FXHW60 PHFO 031535 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 535 AM HST Sun Aug 3 2025 .UPDATE... Update for cancellation of Wind Advisory or leeward Koolau on the island of Oahu. && .SYNOPSIS... Breezy to locally windy trades will persist through this afternoon before slowly trending down into early Monday. Relatively dry and stable conditions will also continue into this evening. Light precipitation carried in on the trades will occasionally wetten windward and upslope mauka regions. The majority of leeward areas will remain dry the next few days. The remnants of Tropical Cyclone Gil will likely pass north of the islands during the middle of the week. This system will disrupt trade flow while increasing statewide rain chances. && .SYNOPSIS... Breezy to locally windy trades will persist through this afternoon before slowly trending down into early Monday. Relatively dry and stable conditions will also continue into this evening. Light precipitation carried in on the trades will occasionally wetten windward and upslope mauka regions. The majority of leeward areas will remain dry the next several days. The remnants of Tropical Cyclone Gil will likely pass north of the islands at mid week. This system will disrupt trade flow and increase statewide rainfall chances. && .DISCUSSION... A 1030 mb high centered approximately 1,500 miles north of Oahu has maintained a tight enough pressure gradient to drive strong winds across many eastern-facing windward exposures and through higher terrain. Last night`s highest wind observations of sustained 30-plus mph winds with gusts approaching 50 mph occurred across such notoriously windy areas as the northern Kohala Coast, the Central Maui Valley, eastern Molokai and atop Oahu`s Koolau Range. A Wind Advisory will remain in effect for these areas (sans Oahu) through the day. Interior dry conditions will persist this afternoon with middle to upper 60 dew point temperatures translating to sub-50% relative humidities (at the lowest) during the heat of the day. Thus, these windy and dry conditions will warrant the continuation of the Red Flag Warning through 6 PM this evening for all leeward areas. 12Z local soundings are still advertising the stout, relatively shallow 5k ft inversion that is assisting in these robust lower level trades. Near 850 mb winds will mix down with surface warming and, with occasional small above surface wind bursts, winds will become gusty especially in non (wind) sheltered areas and downwind of terrain. Gusty winds can fall small trees or tree branches so take heed if outside near or under larger trees. High profile vehicles may be suddenly buffeted within high wind. Also be prepared for power outages. Winds will trend down through the evening with breezy conditions expected through the first half of the week. Lower clouds advancing into the state as verified by recent pre- dawn radar trends do show widely-scattered light showers moving onshore and across windward locales. Any rain will be meager, at best, with the majority of the state staying dry the next few days. The majority of the GFS and EC ensemble (QPF) members show no appreciable rain through mid week. This will only exacerbate the (primarily leeward) moderate to severe drought. Monday through Wednesday`s weather will be one of breezy trades and dry conditions as the high drifts eastward and the local pressure gradient slackens. Trades will likely become disrupted late Wednesday into Thursday as the remnants of Gil pass to our north. The latest National Hurricane Center forecast remains on track with Tropical Storm Gil weakening to a Tropical Depression by tomorrow. Although there is always some amount of uncertainty, the latest model guidance continues to show the highest moisture associated with Gil passing north of Hawaii. The threat for more moderate, persistent rain will remain low and across our northern offshore waters Thursday and Friday. With that being said, there will be an uptick in late week showers but scattered showers will produce the highest QPF in the normal more wet windward exposures. && .AVIATION... Strong high pressure north of the region will help to generate breezy to locally windy northeasterly trades today with a strength similar to yesterday. Scattered showers will mainly affect windward and mauka locations and bring MVFR ceilings and visibility on occasion. Elsewhere, VFR conditions prevail. AIRMET Tango is in effect for moderate with isolated severe low level turbulence over and immediately S through W of the island mountains due to strong trade winds and gusts. This AIRMET will likely be needed through the afternoon. && .MARINE... High pressure north of the state will maintain fresh to locally near gale trade wind speeds across all coastal waters today. As the high weakens and slowly drifts east, trade winds look to ease Monday and Tuesday to the moderate to locally strong range. The current Small Craft Advisory has been extended for all coastal zones through this afternoon before scaling back to the windier waters and channels around Maui County and the Big Island tonight. Trade will continue to ease by the middle of the week as the remnants of Tropical Storm Gil passes to the northeast of the state. Surf along south facing shores will continue to decline today before another moderate, long period south swell is expected to build in early Monday. This swell may peak just below High Surf Advisory (HSA) criteria late Monday and into Tuesday before declining Wednesday. Another swell is expected from a low formed south of New Zealand at the end of July, that measured seas of 35 to 40 feet aimed towards Hawaii. This swell is expected to build on Thursday and hold through the end of the week which could get near HSA criteria at its peak. Short period trade wind swell will keep east facing shores elevated and choppy today due to strong trade winds. By late Monday into Tuesday, a moderate, medium to long period east swell is expected to fill in from the energy from Tropical System Gil in the eastern Pacific. Surf along north facing shores will remain tiny through the afternoon. A small, medium period northwest swell originating from Typhoon Krosa in the western Pacific will bring a small bump up in surf along north facing shores this evening and hold through Monday. Another bump is expected as a small, medium to long period northwest swell looks to fill in Thursday and Friday. && .FIRE WEATHER... A gusty, stable, and rather dry trade wind flow will remain in place through the day, producing critical fire weather conditions, with winds greater than 20 mph and daytime relative humidities as low the lower 40s. A strong lower level inversion will ensure that highest elevations of Big Island and portions of Haleakala on Maui experience very low relative humidity. Winds will slowly ease Sunday into Tuesday, which should cause winds to fall below Red Flag thresholds by Monday. Although the winds weaken, dry conditions will continue to persist through Tuesday. An increase of moisture and shower activity will be possible towards the middle of the week as the remnants of TC Gil pass to our north. && .HFO WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 6 PM HST this evening for Niihau-Kauai South-Kauai Southwest-East Honolulu-Honolulu Metro-Ewa Plain- Waianae Coast-Oahu North Shore-Central Oahu-Waianae Mountains- Molokai North-Molokai West-Molokai Leeward South-Lanai Windward- Lanai Leeward-Lanai South-Lanai Mauka-Kahoolawe-Maui Leeward West-Maui Central Valley North-Maui Central Valley South-South Maui/Upcountry-South Haleakala-Big Island South-Big Island Southeast-Kohala-Big Island Interior. Wind Advisory until 6 PM HST this evening for Lanai Mauka-Maui Windward West-Maui Leeward West-Kohala-Molokai Southeast-Molokai North-Molokai West-Molokai Leeward South-Lanai Windward-Lanai Leeward-Maui Central Valley North-Maui Central Valley South- South Haleakala-Big Island Southeast-Big Island North. Small Craft Advisory until 6 PM HST this evening for Kauai Northwest Waters-Kauai Windward Waters-Kauai Leeward Waters- Kauai Channel-Oahu Windward Waters-Oahu Leeward Waters-Kaiwi Channel-Maui County Windward Waters-Maui County Leeward Waters- Big Island Windward Waters. Small Craft Advisory until 6 AM HST Monday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ UPDATE...Blood DISCUSSION...Blood AVIATION...Thomas MARINE...Shigesato FIRE...Blood