Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
534 FXHW60 PHFO 150618 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 818 PM HST Wed Aug 14 2024 .SYNOPSIS... Moderate trade winds will continue through Thursday, then return to breezy levels Friday through early next week. Showers will favor windward and mauka locations, particularly during the overnight and early morning periods as areas of moisture move through. && .DISCUSSION... A broad surface trough (remnants of former TC Emilia), located around 200 miles north-northeast of Hilo, will continue westward tonight through Thursday night, weakening the local trades to moderate levels. This broad surface trough, combined with a mid- level trough and an increase in low-level moisture, will lead to better shower coverage, primarily for windward and mauka locations. The evening radar reflects this and depicts an increase in shower coverage filling in over the windward waters of the small islands, which should continue into Thursday. A few interior/leeward showers are possible Thursday afternoon, where localized sea breezes form. Breezy trade wind conditions are expected to return Friday through the weekend as the aforementioned trough begins to track away from the state and the deep-layer ridge strengthens. A modest increase in low-level moisture, accompanying another low- to mid- level trough passing to the south, could translate to increasing shower coverage Sunday through Monday, most likely over the eastern end of the state. && .AVIATION... Moderate to locally breezy trades will deliver low clouds and brief showers to windward areas through the forecast period. An approaching trough will weaken winds slightly, veer towards a more easterly direction, and allow an increase in low- level moisture over the western end of the state tonight into Thursday. VFR conditions will prevail with isolated MVFR CIG over windward areas. No AIRMETs are currently in effect. AIRMET Sierra for mountain obscuration may be needed over Kauai and/or Oahu tonight. && .MARINE... Moderate to locally strong trade winds will prevail through early next week. A weak surface trough passing by north of the islands will keep the trade winds below Small Craft Advisory thresholds tonight and Thursday. The trades will strengthen back to SCA levels over the typically windy waters around Maui and the Big Island Thursday night or Friday, then hold at these levels through early next week. Several small long-period swells from the south and southeast will produce small surf along south facing shores through the work week. A more significant south swell will arrive late Sunday and Sunday night, peak above the summertime average Monday, then slowly lower through the middle of next week. Seasonally flat to tiny surf is expected through early next week for north facing shores. East shore surf will remain below normal during the next couple days, then trend higher over the weekend and rise to near seasonal levels early next week. The combination of the full moon and water levels running around 0.5 ft higher than normal should produce minor coastal flooding each afternoon along the shorelines across the state beginning 8/18 and likely continuing through 8/20. A Coastal Flood Statement will eventually be needed as we get closer to the event. && .HFO WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Gibbs AVIATION...Shigesato MARINE...Jelsema