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.
Disorganized -SHRA with embedded +SHRA primarily from Lanai and Molokai SE to the Big Island. While VCTS/TS is not included in TAFs, we cannot rule out an isolated storm this afternoon and evening, generally Oahu to the Big Island. MVFR with periods of IFR CIGS/VIS expected into this evening, especially with +SHRA. Improving VIS/CIGS from NW to SE generally after 29/06Z to more of a VCSH/-SHRA. Kauai will remain NW of the activity with VCSH and usual trade wind flow.
Surface winds remain generally weak. However, thunderstorms could bring brief gusty and erratic winds.
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 Zulu is in effect for light ice from Oahu to the Big Island in layer 140-FL200 with conditions expected beyond 29/22Z.
A surface trough stretches across Maui County waters this morning, and a broad weakening surface low centered roughly 950 nm northeast of the state is keeping the local pressure gradient somewhat weak. As a result, moderate easterly will prevail north of the trough with lighter southerly winds to the south of the trough, and the Small Craft Advisory has been cancelled. However, locally fresh winds are expected near the trough today, and isolated thunderstorms could produce erratic localized wind gusts over gale force. The trough and possible low will weaken near the Big Island Thursday, allowing building ridging to the north to drive moderate to fresh easterly winds over most waters and southerly winds near 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 may develop late Sunday and Monday and require an SCA.
A small northwest swell will continue a slow decline through Thursday then fade on Friday, but a small, short-period north- northwest swell will maintain small surf along northern shores during the next several 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 continue through the weekend. The current swell is expected to produce surf above seasonal averages today, with an additional pulse late Thursday maintaining above average surf into Friday. Surf along south-facing shores will decline gradually this weekend into early next week.
Surf along most east-facing shores will be dominated by wrapping north to north-northeast energy that could produce periods of moderate surf. Strong northeast winds and a large, rough north- northeast swell are possible Sunday night and Monday.
Flood Watch through late tonight for for all Hawaii islands.
