485 FXHW60 PHFO 100618 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 818 PM HST Thu May 9 2019 .SYNOPSIS... Light trade winds will continue into the weekend with land and sea breezes favoring leeward coasts, and isolated afternoon through early evening showers. A weak disturbance aloft will drift through the islands, from Sunday afternoon into Monday, producing a slight bump in windward clouds and showers. Trade wind speeds will pick up by the middle of next week as a high pressure system builds in north of the state. && .DISCUSSION... A weak low level trough roughly 400 miles northeast of the main Hawaiian Islands will linger over the region and help weaken the surface pressure gradients and trade wind flow through the upcoming weekend. Light trade winds will last into the weekend with land and sea breezes favoring windward slopes. A high pressure ridge aloft will continue to cap vertical cloud development over most of the state around 6000 feet and keep fair weather in the forecast due to moderate subsidence through Sunday afternoon. Clouds will tend to form over interior sections each day with cloud bands forming along light trade wind and sea breeze convergence zones. Isolated showers are possible mainly over interior sections in the afternoon and early evening hours as surface heating decreases. Clouds and showers will diminish in the evening hours as offshore land breezes develop. A weak upper level short wave trough will drift into the region from the northwest from Sunday night through Monday. A slight increase in cloud heights and showers is projected on the American (GFS) and European (ECMWF) models, mainly over the windward slopes of Maui and the Big Island as a passing surface trough interacts with this upper level short wave. Both models are in good agreement with increasing shower trends for both islands. High pressure will build back in north of the state from Tuesday into Wednesday with a return to moderate trade winds along with an increase in windward and mauka shower activity. There remains a good chance these refreshing moderate trade winds will stick around from Wednesday through the end of next week. && .AVIATION... Light northeasterly trades will prevail through the night. Though conditions remain rather dry, ISOL -SHRA are forecast to affect mainly the western smaller islands and northeastern portions of the Big Island. Otherwise, expect VFR conditions. No AIRMETS are anticipated tonight. && .MARINE... A surface ridge far northwest of Kauai will maintain northeast trade winds over the Hawaiian coastal waters. However, a trough northeast of the area will keep the trade-wind speeds low to occasionally moderate through Monday morning. The prevailing winds will be light enough to allow nighttime offshore land breezes and onshore daytime sea breezes near the islands. The trough will dissipate early next week and a new high will build in from the northwest. Trade winds will strengthen starting Monday afternoon. Winds could reach Small Craft Advisory levels by the middle of next week. A small northwest swell will slowly subside through Sunday. A small south swell is expected to fill in through Friday. A larger south swell generated well southeast of New Zealand could produce surf approaching the advisory level along south facing shores early next week. Small southeast swells will persist through the middle of next week, but the Big Island will block some of the swell from reaching the smaller islands. Surf will remain quite small along east facing shores due to the light trade winds. && .HFO WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Bohlin AVIATION...JT MARINE...Kinel