268 FXHW60 PHFO 230645 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 845 PM HST Wed May 22 2019 .SYNOPSIS... A light to moderate east- southeast wind flow will prevail across the area through Friday as a high pressure area remains far northeast of the islands. The winds will become more easterly on Friday and Saturday, representing the return of the trade winds. This trade wind flow is mainly moderate in strength that is expected to linger into next wind week. Expect trade wind showers to affect the islands during this stretch, favoring mainly the windward and mountain areas of most islands, especially during the nights and mornings. There will be some local afternoon cloudiness over the lee and interior areas of most islands with isolated showers of as well. && .DISCUSSION... The main Hawaiian Islands is under the western part of an area of high pressure with the center located far northeast of the area. Under this part of the high, the winds are east-southeast, where there is some degree of blocking by the islands upwind. This will lead to daytime sea breezes and nighttime land breezes for especially islands like Kauai, Oahu, and Lanai. This pattern not only raises the humidity up a little, but also the discomfort level as well. The return of the trades is held in check by a stalled front some 450 miles northwest of Kauai. This front will be reinforced by another front, forecast to meet up Thursday night, before pushing eastward. The reinforced front will then stall and weakens some 240 miles northwest of Kauai early Saturday , and remain there through at least the first half of next week. As the front stalls and weakens, it will allow the high to strengthen and the trades, with a more east component, to return on Friday night and Saturday. When it comes back, the flow will briefly be locally strong then softens a notch to mainly moderate speed on Sunday, then hold through at least the first half of next week. Not only we will have the trade wind showers, but under this pattern, a tinge of locally daytime sea breezes and nighttime land breezes will lead to local afternoon cloudiness over lee and interior areas. But during this stretch through Tuesday, the support of ridging in the mid and upper levels will maintain a low level inversion between 6 and 9k feet, which will keep the afternoon showers to a minimum. In the near term, we are looking at a band of showers, aligned northwest to southeast, set to move through the main Hawaiian Islands. The leading edge is about to move ashore of windward Big Island. Mainly fair weather, except for a few spotty windward and mauka showers, will hold for the smaller islands to until near midnight for Maui, Oahu around daybreak Friday, then Kauai about mid morning Thursday, that is if the band is still in one piece. Another shower band, oriented north to south, may impact the islands Thursday night and Friday. clearing the islands by Friday evening. && .AVIATION... A light flow pattern continues across the islands this evening. Patchy broken low clouds over central Kauai should break up as night time cooling sets in. A band of broken low clouds just upwind from the Big Island and the islands of Maui County may spread MVFR ceilings across eastern shores and slopes there later tonight. However, no AIRMETS are in effect at this time. TAFS are predominantly VFR. && .MARINE... A surface ridge will persist and strengthen north of the state, while a stalled front lingers northwest of the offshore waters. This will produce easterly trade winds to Small Craft Advisory speeds around the Big Island tonight, with moderate to breezy southeast winds over Maui County windward waters. Remaining waters are mostly blocked from the southeast flow, so winds will be lighter and more variable there. The front and ridge will slowly shift northwest through the rest of the week, causing winds to back out of the east over the smaller islands by Friday, with easterly trades persisting through next week. Small to moderate surf will continue along south facing shores through Friday. A fairly large, long-period swell is forecast to reach the coastal waters Saturday, and may produce surf near advisory level along south facing shores through Memorial Day. A smaller, reinforcing south swell is possible Tuesday. Surf along north facing shores will be quite small through Thursday, then small to moderate swells are expected to arrive into the middle of next week. Lastly, as winds strengthen northeast of the area over the next day or two, surf will see a bump along east facing shores. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 AM HST Thursday for Alenuihaha Channel, Big Island Windward waters, and waters south of the Big Island. && $$ H Lau/Powell/Kinel