HONOLULU, Hawaii (HawaiiNewsNow) - An increase in showers is expected through Saturday as an upper trough slowly approaches the state from the east. Periods of heavier rainfall will be possible, especially over windward and mauka areas, but the windy trades should keep the showers moving fairly quickly. Winds are expected to slightly decrease later in the weekend and gradually shift out of the east-southeast as a disturbance develops west of the state early next week. This could lead to more unsettled weather especially for the western half of the state during the first half of next week. On Sunday, models show the upper trough just west of Kauai along with an induced surface trough west through southwest of Kauai. The disturbance will cause winds to shift slightly south of east over the western half of island chain and pull unsettled weather northwestward over the island chain. This unsettled weather may last into the middle of next week.
The High Surf Warning for east shores is in effect through Saturday, but the surf will remain elevated at advisory levels into the middle of the new week. Over the next few days, the combination of the large surf, strong onshore winds, high astronomical tides, and elevated ocean water levels will produce wave runup and localized coastal erosion along east facing shores.
A long-period northwest swell arriving late tonight into Friday could produce surf around the advisory level Friday night into Saturday. A smaller northwest swell is expected to fill in Sunday and gradually decrease early next week.