Strong high pressure to the north will slowly weaken tonight through the next several days. As a result, the windy trade winds will remain hazardous tonight before gradually decreasing back down to normal levels tomorrow into next week. Showers will favor windward and mountain areas, staying on the lighter side through the next few days before potentially increasing slightly during the middle of next week.
Windy trade winds are expected to blow through tonight with a few showers passing through windward and mountain areas. Based on satellite and radar, most of these showers are on the lighter side. Based on current observations and highres model guidance, strong to windy trade winds with 50 mph gusts could linger through a good portion of tonight, therefore the high wind advisory has been extended through the overnight hours. The strongest winds will be felt over the windy areas along ridges, through mountainous gaps and downslope mountain areas. By tomorrow the trade winds should decrease considerably back down to the normal summertime levels and remain breezy into next week.
By midweek, trades will further ease as Tropical Storm Genevieve weakens to a post-tropical depression and tracks far northeast of the state, disrupting trade wind flow. Bands of moisture will move over the state, returning typical scattered showers to windward and mauka slopes. Model guidance continue to show a tropical upper level trough shifting just northwest of Kauai by the middle of the week. In addition an area of enhanced moisture may move from east to west across the state. If this comes to fruition, expect a steady increase in low to upper level moisture/clouds and increasing chances moderate to locally heavy windward and mauka showers, especially for the western half of the state.
Breezy to windy trade winds will prevail through early Sunday. Occasional MVFR ceilings and visibilities will occur within SHRA mainly across north through east sections of the islands and in mountain areas. Otherwise, VFR flight conditions will prevail for most locations.
AIRMET Tango for moderate low-level turbulence over and immediately S through W of mountainous terrain of all Hawaiian Islands remains in effect due to the strong trade winds. This AIRMET will remain in effect through tonight.
Strong surface high pressure north of the state will maintain strong to locally near gale easterly trade winds across all coastal waters through tonight. The Small Craft Advisory (SCA) is in effect for all coastal zones through tonight for winds and also seas potentially exceeding 10 feet. Overnight as winds begin to trend down, the SCA has been trimmed back to just the windier waters and channels around Maui County and the Big Island through Sunday. The combination of a strong mid- latitude trough and Tropical Storm Genevieve passing far northeast of the islands induces a weakness in the ridge which will then keep trade winds more moderate to locally fresh for the first half of next week.
Surf along south facing shores will stay below seasonal averages as consecutive small south to southwest medium period swells impact the shorelines through the middle of next week.
East facing shores will remain rough and choppy through tonight due to a combination of strong trade winds and a small, medium period easterly swell generated from Tropical Storm Genevieve that will linger into early next week. By early next week as trade winds gradually weaken, surf will also decline slightly.
Surf along north facing shores will remain flat to tiny through the forecast period except for areas exposed to the easterly trade wrap.
Wind Advisory until 6 AM HST Sunday for Waianae Mountains-Lanai Mauka-Kahoolawe-Maui Leeward West-Kohala-Big Island Interior- Kauai South-Koolau Leeward-Molokai North-Molokai West-Molokai Leeward South-Lanai Windward-Lanai Leeward-Maui Central Valley North-Maui Central Valley South-South Haleakala-Big Island South- Big Island Southeast-Big Island North.
Small Craft Advisory until 6 AM HST Sunday 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 PM HST Sunday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters.
