The flooding threat will continue through tonight as a surface trough shifts over the eastern half of the state in the midst of deep tropical moisture and modest instability. Conditions are expected to improve heading into Thursday, with moderate trade winds returning this weekend.
Showers continue this evening across the eastern two thirds of the state with generally light winds. There's a good mix of VFR and MVFR conditions, with a flip to either one possible throughout much of the period as deep tropical moisture remains in place. Lightning activity has decreased, so took out the VCTS mention for PHTO. Kauai will continue to see more of a normal trade wind pattern with the remainder of the island chain following suit by tomorrow afternoon and evening as this system moves out.
AIRMET Sierra for mountain obscuration remains in effect abv 020 for Oahu through the big Island due to the the widespread low clouds and pockets of moderate to heavy rain showers.
AIRMET Tango for Turbulence for Oahu to the Big Island. Moderate turbulence between 100-FL200. AIRMET Zulu is in effect for light ice from Oahu to the Big Island in layer 140-FL200 with conditions expected beyond 29/04Z.
This evening, a trough is located near Maui and the Alenuihaha Channel. Meanwhile, broad weakening surface low pressure is located far northeast of the state. With a somewhat weak pressure gradient, light to moderate winds are prevailing across the islands. The trough will continue to build eastward tonight, providing a focus for scattered heavy showers and isolated thunderstorms. Some showers or storms could produce erratic localized wind gusts over gale force. The trough will weaken near the Big Island Thursday, allowing building ridging to the north to drive moderate to fresh easterly winds over most waters, but southerly lighter winds will remain near the Big Island. The trough will move south of Big Island Friday, and moderate to locally fresh trades will prevail Friday night into the weekend. Stronger northeast winds will likely require a Small Craft Advisory late this weekend or early next week.
A small northwest swell will continue a slow decline through Thursday then fade on Friday, but a small, short-period north- northeast swell will maintain small surf along northern shores during the next few days. A larger, long-period northwest swell will arrive late Saturday and may push surf above the high surf advisory threshold Sunday. The swell will shift more northerly and may briefly build further on Monday before dropping Tuesday.
A series of overlapping south-southwest swells will maintain south shore surf above seasonal average through the weekend. Surf along south-facing shores will decline to around seasonal average early next week.
Surf along most east-facing shores will be dominated by wrapping north to north-northeast swell energy, producing periods of moderate surf. Strong northeast winds and a large, rough north- northeast swell are possible Sunday night and Monday.
Flood Watch until 5 AM HST Thursday for Big Island East-Big Island Interior-Big Island North-Big Island South-Big Island Southeast-Big Island Summits-Central Oahu-East Honolulu-Ewa Plain-Haleakala Summit-Honolulu Metro-Kahoolawe-Kipahulu-Kohala- Kona-Koolau Leeward-Koolau Windward-Lanai Leeward-Lanai Mauka- Lanai South-Lanai Windward-Maui Central Valley North-Maui Central Valley South-Maui Leeward West-Maui Windward West- Molokai Leeward South-Molokai North-Molokai Southeast-Molokai West-Molokai Windward-Oahu North Shore-Olomana-South Haleakala- South Maui/Upcountry-Waianae Coast-Waianae Mountains-Windward Haleakala.
