| Iowa Mesonet's Twitter Bot, posts the latest "everything" issued by Hawaii's WFO https://twitter.com/iembot_hfo here's the latest AFD, as of now Area Forecast Discussion... CORRECTED National Weather Service Honolulu HI 1028 PM HST Wed Aug 22 2018 .SYNOPSIS... Outer rain bands of Hurricane Lane are sweeping across the Big Island and Maui this evening. Expect increasing showers spreading further northwest to the rest of Maui County and Oahu later tonight and to Kauai by Thursday morning. Expect increasing threats for flash flooding as Lane moves northwestward and these heavy rain bands intensify over the islands. Hurricane Lane will likely bring life threatening conditions across Hawaii through Saturday with damaging winds, dangerous surf, coastal storm surge and intense flooding rains. && .DISCUSSION... Please note that tropical cyclone operations are in effect. To incorporate the latest forecast information from the Central Pacific Hurricane Center (CPHC), public forecast updates from the Honolulu Forecast Office will be delayed to immediately follow the latest forecast package from CPHC. The outer rain bands from Hurricane Lane are surging northward this evening across the Big Island and eastern Maui County. Expect the deep unstable tropical moisture to spread these clouds and showers across the rest of the state this evening. Shower intensity within these bands will increase as Hurricane Lane approaches the islands with rapidly increasing threats for flash flooding as Lane moves northwestward. Hurricane Lane will likely bring life threatening conditions across Hawaii through Saturday with damaging winds, dangerous surf, coastal storm surge and intense flooding rains. Listen to local official for recommended preparedness actions, including possible evacuation. If ordered to evacuate, do so immediately. Expect increasing winds as a strong high pressure ridge far north of the islands interacts with Hurricane Lane approaching the Hawaiian Islands from the south. As of 8 PM HST, Hurricane Lane was located roughly 260 miles south of Kona and moving northwest at 7 MPH. The movement on Lane has slowed a down a bit as the steering flow changes with Lane moving around the upper level ridge axis. The forecast from the Central Pacific Hurricane Center (CPHC) continues to track Lane north-northwest towards the center of the state. Based on the latest CPHC forecast advisory #34 at 8 PM HST the center of Lane will pass roughly 125 miles west of Kona on Friday morning around 8 AM HST. The location of these damaging wind impacts will depend heavily upon the final track of Hurricane Lane as it tracks. The onset of tropical storm force winds on the Big Island could start by early Thursday morning, with hurricane conditions expected in some areas Thursday afternoon or Thursday night. The highest wind threats for the Big Island will develop along the western slopes of the island as strong and gusty down slope winds interact with mountainous terrain. Over Maui County, damaging tropical storm conditions will likely begin by Thursday, with dangerous hurricane force conditions expected starting on Thursday night into Friday morning. On Oahu, damaging tropical storm conditions could begin late Thursday night into Friday morning, with dangerous hurricane conditions are expected starting Friday afternoon into Friday night. Hurricane Warnings may need to be expanded to include Kauai County as Lane draws closer. Deep tropical moisture surrounding Lane will also drift northward ahead of the hurricane through the weekend. Extreme moisture levels surrounding Lane will create an unstable environment with muggy and humid weather conditions along with frequent showers. Heavier rain shower bands will develop with some thunderstorm activity as the extreme moisture interacts with mountainous terrain on each island. These conditions will likely lead to periods of hazardous flash flooding threatening all islands. Hence, a Flash Flood Watch remains in effect for the entire state of Hawaii through Saturday. Flood Advisories and Flash Flood Warnings will likely be issued for local areas across the state as the heavy rain intensifies. The combination of a deep moist unstable layer and strong low level wind shear along and to the east of the track of Lane will make tornadoes and large waterspouts a distinct possibility in the rainbands across the right semicircle of the hurricane. These continue to be included in the TCV and HLS products as an elevated threat from Oahu to the Big Island. Will be able to better refine the threat as Lane approaches each island. Unfortunately it's not possible to know which islands will see the worst storm effects right now due to the close proximity of the hurricane track to the Hawaiian Islands and uncertainties in Lane's track caused by increasing wind shear through the atmosphere as Lane moves northward. The CPHC forecasts continue to show that all islands are at risk from direct effects from the core of Hurricane Lane. Everyone should take this hurricane very seriously and should prepare accordingly. It's also important to expect future adjustments to the track and intensity forecast, particularly with the challenging recurvature forecast that Lane is presenting. Prepare for the worst and hope for the best. Sunday through Tuesday, there remains a considerable amount of uncertainty in the model guidance as to when the deep moisture in the wake of Lane departs the region. The American GFS model continues to show a deep moisture plume lingering over the entire state through the weekend and into the first half of next week. While the European (ECMWF) model shows a large area of drier air moving in with the easterly trade wind flow. We will need to wait to see how fast Lane transits the Hawaiian Islands and watch for the models trending towards a more consistent solution over this time period. && .AVIATION... Deep layered clouds and numerous rain showers, the outer bands of Hurricane Lane, are affecting windward portions of the Big Island and Maui. An AIRMET for mountain obscuration has been posted for north through east sections of the Big island and Maui. Conditions will expand westward over the next 24 hours and will likely prompt additional mountain obscuration AIRMETS. Isolated IFR ceilings and visibilities are to be expected in locally heavy downpours along east and southeast facing slopes and coasts of the Big Island tonight. IFR conditions may become widespread on Thursday throughout the eastern half of the state. Thunderstorm activity is likely across waters south and west of the Big Island on Thursday...and possibly Leeward Big Island as well. The sharp contrast of strong high pressure to the north and falling pressures to the south will result in increasingly strong straight-line winds across most of the state. AIRMET Tango is currently in effect for mechanical low level turbulence to the leeward side of all mountains. Conditions are expected to gradually intensify over the next twenty-four hours. && .MARINE... Hurricane Lane, currently located around 225 nautical miles south of Kailua-Kona, is now tracking toward the northwest around 6 knots and is forecast to pass very close to the leeward waters of the smaller islands Thursday through Saturday. Conditions have already begun to deteriorate over the Big Island and Maui County waters due to a large area of heavy showers and strengthening winds. A similar trend is expected across the Oahu and Kauai waters late tonight through the day Thursday as Lane approaches. Impacts associated with Lane tonight through Saturday will include: hazardous seas, life-threatening surf (warning level; quickly building overnight through Thursday night), beach erosion, overwash onto vulnerable coastal roadways as Lane makes its closest approach, and storm surge (surge guidance estimating ranges from 2 to 5 feet with impacts potentially occurring on all islands) along exposed coasts/harbors. See the latest coastal hazard message and local statement for additional details with regards to expected/potential impacts for each island. See the latest Oahu Surf Discussion (SRDHFO) for more details on surf and swell from other sources. && .HFO WATCHES/WARNINGS/ADVISORIES... Hurricane Warning for Oahu-Molokai-Lanai-Kahoolawe-Maui-Big Island. Hurricane Warning for Kauai Channel- Oahu Leeward Waters-Kaiwi Channel-Maui County Leeward Waters- Maalaea Bay-Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters- Big Island Southeast Waters. Hurricane Watch for Niihau-Kauai. Hurricane Watch for Kauai Northwest Waters- Kauai Windward Waters- Kauai Leeward Waters. Tropical Storm Warning for Oahu Windward Waters- Maui County Windward Waters- Big Island Windward Waters. Flash Flood Watch through late Friday night for all Hawaii islands. High Surf Warning until 6 AM HST Friday for Kona-South Big Island. High Surf Warning from 6 AM Thursday to 6 PM HST Friday for Niihau- Kauai Windward- Kauai Leeward- Oahu South Shore- Waianae Coast- Molokai Leeward- Lanai Makai- Kahoolawe- Maui Leeward West- Maui Central Valley- Leeward Haleakala. High Surf Advisory until 6 AM HST Thursday for Niihau- Kauai Windward- Kauai Leeward- Oahu South Shore- Waianae Coast- Molokai Leeward- Lanai Makai- Kahoolawe- Maui Leeward West- Maui Central Valley- Leeward Haleakala. && $$ DISCUSSION...Bohlin AVIATION...Powell MARINE...Gibbs |