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 trade winds will continue for the next few days. Low ceilings and passing showers will be possible over windward and mountain locations. Although MVFR conditions will be possible within passing showers, VFR should prevail for most locations.
AIRMET Tango remains in effect for moderate low-level turbulence over and downwind of island terrain. This AIRMET will likely be needed for at least the next few days.
Issued at 336 AM HST Sun May 24 202
Strong easterly trades will persist through tonight, then ease into the fresh to strong category through the first half of the week as the ridge weakens north of the state. This will allow the Small Craft Advisory to continue for all waters through tonight, then for the typically windier waters and channels from Monday through much of the week.
Surf along south facing shores will remain at similar levels today before gradually lowering Monday as a medium-period south swell lingers. This is supported by overnight 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 later in the 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 today before lowering Monday as a small north-northwest swell moves through. This is supported by overnight 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 this 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 AM HST Monday for Big Island Windward Waters-Kaiwi Channel-Kauai Channel-Kauai Leeward Waters- Kauai Northwest Waters-Kauai Windward Waters-Maui County Leeward Waters-Maui County Windward Waters-Oahu Leeward Waters-Oahu Windward Waters.
Small Craft Advisory until 6 PM HST Tuesday for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Maalaea Bay-Pailolo Channel.
