273 FXHW60 PHFO 150651 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 851 PM HST Sun Apr 14 2019 .SYNOPSIS... Trade wind weather will persist across the islands this week. Trade winds will become lighter by Tuesday as the high, currently north of the islands, moves east of the islands. Breezy trades will return by Friday as a strong surface ridge settles north of the islands. && .DISCUSSION... Things continue to quiet down this evening. The breezy trades are finally showing signs of weakening. Many of the automated wind sensors on Maui, are reporting lighter conditions there. Many wind sensors on the Big Island, although still breezy, have maxed out, and a slow downtrend has begun.The wind advisory, which goes through 6 am HST Monday, could be taken down by midnight tonight, but we will let it go and lower it at 4 am HST when the new forecast package goes out. This downturn in the trades comes about as the surface high weakening north of the islands, while moving toward the east during the next 24 to 48 hours. The trades are expected to bottom out on Tuesday night, followed by an upturn to locally strong by Wednesday night. Trades will continue to strengthen, reaching moderate to strong area-wide by Friday. It will stay this way through the upcoming weekend. The heavy rains and thunderstorms that have affected the Big Island have for the past few days, are done. Mid level ridging is now taking place as the trough gradually fills. The low level inversion should be in place area wide by Monday afternoon, between 6 and 8k feet. On top of that, a pocket of dry air, along with this stable air mass, will keep the trade showers below its normal frequency through Tuesday. An uptick in trade showers will occur Tuesday night, as not only an area of higher precipitable water arrives, but a passing short wave trough aloft temporarily weaken the low level inversion, causing it to rise to 10k feet. During the latter part in the week, the mid level ridge weakens over the eastern part of the island chain, causing the inversion to rise to 12k, leading to a more frequent shower pattern for windward Maui and windward Big Island. As for this evening, Kauai, Oahu and Molokai, looks pretty dry, with lack of showers immediately upwind of these islands. Windward Maui, and especially windward Big Island, continues to be showery, with more shower bearing clouds upwind of these two islands. && .AVIATION... A nearly stationary surface high far north of the islands continues to support strong and gusty trade winds. AIRMET TANGO will likely remain posted through Monday for low-level turbulence near and downwind of the mountains, despite gradually easing trade winds. Trade winds will deliver randomly distributed low clouds and brief showers that will primarily affect windward areas, and VFR conditions will prevail. && .MARINE... Strong high pressure centered far north of the area is responsible for the rather strong trade winds being experienced over the coastal waters. A Small Craft Advisory is currently posted for the entire area through tonight due to the combination of the strong trades and resulting rough seas. The high is forecast to gradually weaken on Monday and become centered far northeast of the area by Tuesday. The result will be for decreasing winds and lowering seas. As the trades begin to ease Monday, the Small Craft Advisory (SCA) will likely be scaled back to the typical windy zones around Maui County and the Big Island on Monday and drop below SCA levels Monday night. Strong trade winds may return later in the week as high pressure rebuilds northeast of the state. The seas associated with the strong trades has resulted in a High Surf Advisory being in effect along most east facing shores through tonight. Seas are expected to gradually lower tonight but will continue to monitor buoy output to determine if the High Surf Advisory needs to be extended into Monday. A new small northwest swell is expected to fill in tonight and Monday, then linger on into Wednesday. Another small northwest swell is expected to arrive Thursday night and Friday. Surf heights will remain below High Surf Advisory levels. There will also be a series of small, mainly background south swells through this week. && .HFO WATCHES/WARNINGS/ADVISORIES... High Surf Advisory until 6 AM HST Monday for Kauai Windward-Oahu Koolau-Olomana-Molokai Windward-Maui Windward West-Windward Haleakala-South Big Island-Big Island North and East. Wind Advisory until 6 AM HST Monday for Lanai-Kahoolawe-Maui Leeward West-Maui Central Valley-South Big Island-Kohala-Big Island Interior. Small Craft Advisory until 6 AM HST Monday for all Hawaiian waters. && $$ H Lau/Powell/Kino