Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
591 FXHW60 PHFO 161523 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 523 AM HST Sun Aug 16 2026 .SYNOPSIS... Tropical Storm Lala will continue to affect the state today as it moves westward to the south of Oahu and Kauai. Areas of damaging winds will persist, mainly across the western end of the state, and the threat of heavy flooding rainfall will continue on all islands. As Lala moves west of Kauai tonight and Monday, strong easterly winds will slowly diminish, and the threat of flooding will decrease. A drier moderate to locally breezy trade wind flow will prevail Tuesday through the end of the work week. && .DISCUSSION... Recently downgraded Tropical Storm Lala produced an exceptional amount of rain on southeast and east the Big Island during the night, where numerous gages recorded rain accumulations of more than 10 inches during the past 12 hours. Torrential flooding rainfall hit the Kau District particularly hard, with many gages reporting more than 15 inches during this time and several gages picking up more than 4 inches of rainfall in one hour. Rain rates and wind have decreased considerably on the Big Island during the past several hours. The focus of heavy rainfall has moved to Maui County and Oahu during the past several hours. Lala has also produced widespread easterly winds that have gusted above 60 mph from Big Island to Oahu during the night, and many stations along and downwind of terrain on Big Island and Maui reported hurricane force wind gusts. As Lala moved westward, winds have largely abated on Big Island and have shown modest declines on Maui County. This has resulted in numerous reports of downed trees and roof damage. Tropical storm conditions are expected to affect all islands today, with conditions gradually improving from east to west later today and tonight. The Flood Watch has been extended for Big Island and Maui County, where saturated conditions will not require much additional rainfall to produce flash flooding. The Flood Watch remains in effect on Oahu and Kauai, where the heaviest rainfall, as much as 8 inches, is most likely today as Lala passes to the south. Widespread tropical storm force winds will be most likely from Maui to Kauai today, with a decreasing trend over the eastern half of the state during the afternoon. Remember impacts can occur well outside the center of the tropical storm. Please stay up to date on the latest forecasts, and prepare for the impacts described below. In anticipation of critical new updates with each of the advisory packages issued by the National Hurricane Center (NHC), the NWS Honolulu will continue delaying the issuance of our typical forecast package products (AFD, SFT, PFM, ZFP, SPF, CWF, etc.) until after the release of NHC`s suite of products, to incorporate the latest and most up-to-date information on Tropical Storm Lala. As Lala departs to the west, winds will ease to moderate to locally breezy trades. Windward areas may remain wet with some risk for flooding due to a band of moisture trailing Lala. A drier and more stable moderate trade wind flow will develop by Tuesday and will persist through the end of the work week. && .AVIATION... Tropical Storm Lala continues moving WNW and is west of the Big Island. TAF sites state wide will experience strong winds gusting to tropical storm force and heavy SHRA with isol tstms. IFR/MVFR conds will be common in heavier SHRA and any tstms. AIRMET SIERRA is in effect for IFR for Oahu through Maui. This will change as Lala continues to move up the state. AIRMET TANGO is in effect for mod to isol svr turb lee of terrain. TANGO is also in effect for SFC winds greater than 30 kts for Oahu to Maui and may need augmented to account for the movement of Lala. && .MARINE... At 3 AM HST this morning, Tropical Storm Lala was moving northwest at around 15 knots with its low level center approximately located 105 nm west of Kailua-Kona, Big Island or 90 nm south of Honolulu. A Tropical Storm Warning is now in effect for all the Hawaiian coastal waters. Large east-facing shore surf peaked last night on Big Island and Maui as former Hurricane Lala approached and passed just south of Big Island. Surf for the east-facing shores of Oahu and Kauai are peaking at advisory levels this morning. Overall, surf will gradually fall below advisory levels along all east facing shores this afternoon. High Surf Advisories are now in effect for all east-facing shores through 2 PM HST this afternoon. North-facing surf will remain rough today as a result of this short period, Lala wind wave-driven chop in tandem with an east swell wrap. South-facing shore surf will stay below advisory thresholds but remain elevated from a combination of lingering medium period south swell and Lala short period east swell. South shores will likely experience a minor boost in surf from trailing short period east swell energy from Lala as it travels into the far west offshore waters Monday morning. Longer period south swell energy generated from gales just east of New Zealand will begin arriving late this week. && .FIRE WEATHER... Increasing humidity and rainfall with Lala will remove fire weather concerns in the short term. The temperature inversion will not be present today. Moderate trade winds will prevail Monday through at least Thursday. && .HFO WATCHES/WARNINGS/ADVISORIES... Flood Watch through late tonight for Niihau-Kauai Leeward-Kauai Mountains-Waianae Coast-Oahu North Shore-Olomana-Central Oahu- Waianae Mountains-Kauai North-Kauai East-Kauai South-East Honolulu-Honolulu Metro-Ewa Plain-Koolau Windward-Koolau Leeward. High Surf Advisory until 2 PM HST this afternoon for Niihau- Olomana-Maui Windward West-Kauai East-Kauai South-Koolau Windward-Molokai Windward-Molokai Southeast-Windward Haleakala- Kipahulu-South Haleakala-Big Island Southeast-Big Island East- Big Island North. Tropical Storm Warning for all Hawaii islands- Flood Watch through this afternoon for Lanai Mauka-Kahoolawe- Maui Windward West-Maui Leeward West-Haleakala Summit-Kona- Kohala-Big Island Interior-Big Island Summits-Molokai-Lanai Windward-Lanai Leeward-Lanai South-Maui Central Valley North- Maui Central Valley South-Windward Haleakala-Kipahulu-South Maui/Upcountry-South Haleakala-Big Island South-Big Island Southeast-Big Island East-Big Island North. Tropical Storm Warning for all Hawaiian waters- && $$ DISCUSSION...Thomas/Wroe AVIATION...Walsh MARINE...Blood FIRE WEATHER...Thomas