Breezy easterly trade winds will persist through Wednesday, then ease into the light to moderate range from Thursday through Saturday. Clouds and showers will favor windward and mauka areas, with a period of increased shower activity possible Wednesday night into Thursday as a band of moisture moves through the islands. A few afternoon clouds and showers may develop over interior and leeward areas Thursday through Saturday where localized sea breezes form. Trade winds are expected to strengthen again late this weekend and into early next week.
Short-range guidance remains in good agreement and depicts breezy easterly trade winds persisting through midweek as a strong subtropical ridge remains anchored north of the state. A band of moisture approaching the Big Island this evening, combined with an elevated trade wind inversion near 10 kft and a weak upper-level trough, is expected to bring increased shower activity to windward portions of the Big Island and Maui later tonight through Wednesday morning. Guidance indicates a modest increase in low- level moisture during this period, with precipitable water values climbing above climatological normals to over 1.5 inches. This moisture may linger through Thursday morning, supporting enhanced rainfall chances across windward areas, potentially expanding to all windward sections of the island chain by Wednesday night.
The surface ridge north of the islands is forecast to weaken from Thursday through Saturday, allowing trade winds to ease into the light to moderate range. At the same time, a drier and more stable air mass is expected to move into the region. As a result, shower activity should become more limited, with passing showers favoring windward and mauka areas during the overnight and early morning hours. Localized sea breezes will develop each afternoon, leading to a few clouds and showers over interior and leeward areas, particularly from Thursday through Saturday.
By late in the weekend and into early next week, strengthening surface ridge north of the state should support a return to a more typical breezy trade wind pattern.
High pressure north of the islands will continue to sustain moderate to locally breezy trade winds through tonight and tomorrow. The latest balloon sounding from Hilo shows an elevated inversion height to 10,000 feet, therefore more frequent showers are expected over Big Island and Maui windward areas tonight. For the rest of the islands, shower coverage will be little less, focusing mostly over windward and mountain areas. MVFR conditions are expected within showers, while VFR prevails elsewhere.
No AIRMETs are in effect, however there is a decent chance for AIRMET Sierra for windward areas of the Big Island and Maui due to the increasing showers.
Surface ridge north of the area will hold through Wednesday, then weaken Thursday through Saturday as a front passes far north of the state. Moderate to locally fresh trades will persist through Wednesday before easing to light to moderate category Thursday through Saturday. Fresh to locally strong easterly trades will return Sunday through early next week.
A series of southern hemisphere swells will continue through the week with the larger south swell of the week due to arrive this weekend. Currently, a small, medium-period south swell is overlapping a fading swell, producing near seasonal average surf along south facing shores. These swells will slowly decline Wednesday into Thursday. A smaller pulse of south-southwest swells will fill in late Thursday into Friday keeping surf elevated along south facing shores.
Long-period energy from a storm that passed within our swell window around New Zealand earlier this week is expected to gradually fill in locally through the weekend. Wave models have this swell peaking Sunday into Monday that could drive surf heights to near the warning level. This swell will coincide with the peak monthly tides and will likely lead to significant wave runup and minor coastal flooding during the first half of next week, particularly during the peak daily high tide cycles.
A small west-northwest swell will hold into Wednesday and fade Thursday. East shore surf will slowly decline below seasonal averages Wednesday through the rest of the week as trades ease.
None.
