textproduct: Honolulu

SYNOPSIS

Tropical Storm Lala will move over or just south of Big Island today and continue to the west northwest or west through the remainder of the weekend. Wind, rain and surf impacts will be felt statewide. A Hurricane Warning is in effect for Big Island and a Tropical Storm Warning is in effect for the rest of the state. Trade wind weather will return by Monday.

DISCUSSION

The main forecast concern through late Sunday will be impacts from Tropical Storm Lala. As of 5 AM HST this morning, Tropical Storm Lala was located about 110 miles southeast of South Point moving west northwest around 13 mph. The center of rotation can be picked up on radar as it drifts closer towards our local coastal water zones. Based on the latest forecast from the National Hurricane Center, Lala is expected to move over or near the southern end of the Big Island by this afternoon, then continue moving to the west northwest, with the center of circulation remaining south of the smaller islands. Remember impacts can occur well outside the center of the storm. Please stay up to date on the latest forecasts, and prepare for the impacts described below.

STRONG AND GUSTY WINDS...Damaging tropical storm force winds (39 mph to 73 mph) have already begun across parts of the Big Island, and may begin across Maui County as early as late this morning, Oahu as early as this evening, and Kauai as early as tonight. A Hurricane Warning is in effect for the Big Island and surrounding waters due to a non- negligible chance of hurricane force winds (74 mph or greater). A Tropical Storm Warning is in effect for the rest of the state and surrounding waters. Localized areas of highly enhanced and damaging winds are possible over and downwind of the mountainous terrain, even well away from the tropical cyclone center. These localized strong winds and gusts will also be felt in advance of the arrival of Lala and should be kept in mind as last minute preparations are being made.

HEAVY RAINFALL...Periods of heavy rainfall associated with Tropical Storm Lala have already begun to affect the Big Island, and are expected to reach Maui County by this afternoon, and Oahu and Kauai by this evening into Sunday. Orographic enhancement will result in locally higher rainfall totals where moist tropical flow interacts with island terrain. If heavier rainfall persists over the same locations, flash flooding and rapidly rising streams are possible. The location of heaviest rain will likely favor windward portions of the Big Island and Maui. The current forecast for windward portion of the Big Island has 10 to 20 inches of rain, with locally higher amounts. Rainfall totals of 8 to 12 inches are possible on windward Maui and up 8 inches of rainfall could occur across the remainder of the island chain. While the highest rainfall amounts will be focused over windward areas, leeward areas will also have a significant flood risk. Heavy rain could persist into Monday for some areas. A Flood Watch remains in effect for the Big Island and Maui County through late tonight, and for Oahu, Kauai, and Niihau from this evening to early Monday morning.

LARGE AND ROUGH SURF...Lala is expected to generate a large easterly swell as it moves northwestward. Surf may build along exposed east and southeast facing shores from east to west as the system approaches. A High Surf Warning remains in effect for east facing shores of Big Island, Maui, Molokai and Oahu, and a High Surf Advisory is posted for east facing shores of Kauai. Very large and extremely rough seas are expected to rapidly increase Saturday and Sunday on exposed southeast and east shores and may produce damaging surf, significant beach erosion, and overwash across vulnerable coastal infrastructure, mainly on the Big Island of Hawaii. Highest storm surge up to 3 feet is forecast for the eastern side of the Big Island.

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.

Trade winds will resume through the middle of next week in the wake of Lala's departure.

AVIATION

The center of Tropical Storm Lala is approximately 110 nm southeast of Hilo early this morning and is moving west northwest at around 10 knots. Lala is forecast to pass in the vicinity of South Point, Big Island this afternoon. Island-wide TAF sites will experience strong northeast winds gusting to tropical storm force through the period. Ceilings will lower to MVFR to occasional IFR and visibilities will deteriorate within periods of heavy rain from east-to-west through early Sunday.

A Big Island and Maui AIRMET for surface winds greater than 30 knots and IFR conditions is currently in effect.

AIRMET SIERRA is currently in effect for north through east areas of Big Island, Maui, Lanai and Molokai for mountain obscuration above 2500 feet.

AIRMET TANGO for moderate turbulence remains in effect immediately south and west of mountains due to low level winds. TANGO likely continue the next couple of days.

MARINE

NE winds continue to strengthen today as Tropical Storm Lala passes very near the southern tip of the Big Island. The strongest winds are anticipated Saturday evening into Saturday night for the waters surrounding the Big Island and Maui. Winds peak for the waters surrounding Kauai and Oahu during Sunday. Hurricane Warnings and Tropical Storm Warnings remain in effect for all coastal and offshore waters. Expect dangerous conditions including torrential rainfall, a few thunderstorms, and high surf. Lala will track WNW through the weekend, clearing the western islands by Monday. Tuesday into the rest of the week, a return to easterly trades across the region is expected.

Surf increases quickly today along east facing shores as a medium- period swell generated by Tropical Storm Lala fills in. The High Surf Warning remains in effect for E facing shores of the Big Island and Maui as well as the SE facing coasts of the Puna and Ka'u Districts where the highest surf is expected. Surf is also forecast to reach low end warning criteria for E facing shores of Oahu and Molokai and advisory levels for Kauai. Surf will rapidly decline Saturday night for the southern islands but may take until Sunday to fall below advisory threshold for Oahu and Kauai as Lala begins to gain distance from the island chain.

For N shores, anticipate choppy conditions with swell energy wrapping from the east through the weekend. For S shores, surf will remain below the advisory threshold but may experience a small boost in short-period swell as Lala tracks south of the island chain on Saturday night. Longer period energy from a distant Southern Ocean swell will also help to maintain south shore surf Sunday into Monday.

FIRE WEATHER

Increasing humidity and rainfall with Lala will remove fire weather concerns through at least early next week. The temperature inversion will not be present today.

HFO WATCHES/WARNINGS/ADVISORIES

Tropical Storm Warning for Niihau-Kauai Leeward-Kauai Mountains- Waianae Coast-Oahu North Shore-Olomana-Central Oahu-Waianae Mountains-Lanai Mauka-Kahoolawe-Maui Windward West-Maui Leeward West-Haleakala Summit-Kauai North-Kauai East-Kauai South-East Honolulu-Honolulu Metro-Ewa Plain-Koolau Windward-Koolau Leeward- Molokai-Lanai Windward-Lanai Leeward-Lanai South-Maui Central Valley North-Maui Central Valley South-Windward Haleakala- Kipahulu-South Maui/Upcountry-South Haleakala.

Flood Watch from this evening through late Sunday night 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 Warning until 6 AM HST Sunday for Olomana-Koolau Windward-Molokai Windward-Molokai Southeast.

Flood Watch through late tonight 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.

High Surf Warning until 6 AM HST Sunday for Maui Windward West- Windward Haleakala-Kipahulu-South Haleakala-Big Island Southeast- Big Island East-Big Island North.

Hurricane Warning for Big Island-

High Surf Advisory until 6 AM HST Sunday for Kauai East-Kauai South.

Tropical Storm Warning 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-Maalaea Bay-Pailolo Channel.

Hurricane Warning for Alenuihaha Channel-Big Island Windward Waters-Big Island Leeward Waters-Big Island Southeast Waters.

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.

Small Craft Advisory until 6 AM HST early this morning for Kaiwi Channel-Maui County Windward Waters-Maui County Leeward Waters- Maalaea Bay-Pailolo Channel.