For late this evening, isolated afternoon showers will be mainly limited to interior regions and along mountain slopes. Expect a slight uptick in shower activity along windward areas Sunday into Monday, as trades strengthen and an area of marginally enhanced moisture pushes across the state. From Tuesday through Friday, there will be a return to light winds with afternoon sea- breeze development and isolated mainly interior showers.
Moderate and rather stable trade winds will persist through the weekend. A small area of low level moisture will be focused over windward slopes of Maui County, where AIRMET Sierra for mountain obscuration may be needed overnight. The moisture may spread to windward Oahu on Sunday. VFR conditions will prevail elsewhere, except for isolated MVFR slopes over leeward terrain in the afternoon.
A long-period south-southwest (200 degree) swell will build tonight and peak Sunday night into Monday before gradually declining through the rest of the week. Near shore buoys, including Lanai and Barber's Point, show wave heights increasing this evening with a dominant 22 second period. Expect the swell to continue to fill in tonight into Sunday morning. Surf heights will increase along exposed south and west facing shores with surf heights reaching advisory levels. A High Surf Advisory remains in effect tonight and continues through Monday night. Surf could also reach warning levels Sunday night into Monday (advisory along west facing shores), but confidence is a bit lower over 24 hours out from the forecast peak. Will continue to monitor buoys and future guidance for the possibility of upgrading.
This swell will also coincide with the peak monthly tides which will add the potential for significant wave runup on top of minor coastal flooding potential during the monthly peak tides through the first half of next week. Once the peak swell passes, south shore surf will remain elevated through much of the week due to the slow decline of this large south swell and a series of continued overlapping southerly swells.
Very little swell energy is arriving along north-facing shores, keeping surf tiny to flat. A small bump in surf is possible early next week with the arrival of a small northwest swell and a smaller north swell. Gentle to moderate east-northeasterly winds expected through next week as a weak front is held up to the north and west of Hawaii. Surf along east facing shores will remain small as a result.
A Coastal Flood Statement remains in effect for minor coastal flooding of vulnerable low-lying coastal roadways, docks, boat ramps and other coastal infrastructure. Peak monthly high tides combined with water levels that are running higher than predicted will lead to minor flooding potential around the daily peak tide, which will be during the late afternoon and early evening hours, through at least Tuesday. While minor coastal flooding is expected along all shorelines, the combination of the south-southwest swell, King Tides and the daily high tide will make low-lying coastal areas along south and west shores susceptible to more widespread coastal flooding through the first half of next week.
High Surf Advisory until 6 AM HST Tuesday for Big Island South- Big Island Southeast-East Honolulu-Ewa Plain-Honolulu Metro- Kahoolawe-Kauai South-Kauai Southwest-Kipahulu-Kohala-Kona-Lanai Leeward-Lanai South-Maui Central Valley South-Maui Leeward West- Molokai Leeward South-Molokai Southeast-Niihau-South Haleakala- South Maui/Upcountry-Waianae Coast.
