Several high pressure systems passing through the North Pacific basin will maintain a broad ridge north of the Hawaiian Islands for at least the next seven days. This ridge strength and position will maintain moderate to locally strong easterly trade winds across the region with only subtle day to day wind speed changes through next weekend. A narrow upper level trough with several embedded upper lows will remain anchored across the region keeping periods of trade wind showers in the forecast for the foreseeable future. These passing showers will favor windward and mountain areas in the overnight to early morning hours.
Breezy to locally windy trades will continue for next few days. Low cigs and SHRA expected over windward and mauka locations. MVFR conds possible but VFR should prevail.
AIRMET Tango is in effect for low-level turb over and downwind of terrain.
Strong easterly trades will persist through Sunday, then ease slightly into the fresh to strong category through the first half of next week as the ridge weakens slightly north of the state. This will allow the Small Craft Advisory to continue for all waters through at least Sunday afternoon, then likely remain in effect for the typically windier waters and channels by Monday.
Surf along south facing shores will remain at similar levels through Sunday before gradually lowering Monday as a medium-period south swell lingers. This is supported by evening observations at the NDBC 51002 buoy south of the islands, which depict a steady trend with peak energy centered around the 15-second band. A fresh long-period south swell will arrive Tuesday, then build to near seasonal average through midweek before slowly easing Thursday.
Looking ahead to late next week, a more significant long-period south-southwest swell is expected due to a storm-force low currently located southeast of New Zealand. Satellite data shows a large fetch of 40 to 50 kt winds generating seas of 35 to just over 40 ft, focused toward Hawaii along the 190-degree directional band. Expect surf to begin building locally Friday with 20+ second forerunners, then peak above advisory levels next weekend.
Surf along exposed north and west facing shores will hold through Sunday before lowering Monday as a small north-northwest swell moves through. This is supported by evening observations at the NDBC 51001 buoy northwest of the islands, which depict a steady trend with peak energy centered around the 13-second band. Late- season North Pacific activity will continue next week due to a storm-force low currently located around 2000 nautical miles northwest of the state and tracking northeastward toward the Aleutian Islands. Although the bulk of the energy will remain focused northeast of the islands, expect long-period forerunners to arrive Tuesday, with this source gradually building down the island chain thereafter. Above-average surf is likely by daybreak Wednesday near the peak before lowering Thursday.
Surf along east facing shores will remain rough through Tuesday, then gradually lower by midweek as the trades ease slightly.
Small Craft Advisory until 6 PM HST Sunday for all Hawaiian Waters and Channels.
