385 FXHW60 PHFO 011300 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 300 AM HST Sun Jun 1 2025 .SYNOPSIS... Moderate to locally breezy east-southeast trades will hold in place through Monday, as a broad surface trough develops to the west of the state. A disturbance aloft may enhance the trade showers a bit during this time, with showers favoring east and southeast facing slopes and coasts at night, and leeward areas each afternoon. The trough will dampen out and shift westward Monday night and Tuesday, bringing a return of moderate to locally breezy east-northeast trades, and a windward and mauka focused shower pattern. This pattern will hold in place through the remainder of the work week, with the trades potentially easing next weekend. && .DISCUSSION... Currently at the surface, a strong 1037 mb high is centered around 2000 miles north-northeast of Honolulu, with a weakening cold front around 1000 miles west-northwest of Kauai. Closer to the islands, a trough of low pressure is developing around 200 miles west of the Garden Isle. The low-level trade flow is responding to the developing trough, shifting east-southeast at moderate speeds in areas not sheltered by terrain. Infrared satellite imagery shows increasing high clouds moving overhead, along with lower clouds moving along with the trades. Overall, partly to mostly cloudy conditions prevail across the state early this morning. Radar imagery shows scattered to numerous showers moving into east and southeast facing slopes and coasts, with a few showers also affecting portions of leeward Oahu and leeward Big Island. Main short term focus revolves around trade wind trends and there impact on rain chances during the next couple days. Strong high pressure will remain far to the north-northeast of the state through Monday, while the front and trough merge into a broad trough a few hundred miles west of the island chain. This will keep moderate to locally breezy east-southeasterly trades blowing, with some terrain sheltered leeward areas experiencing sea and land breezes. Showers will favor east and southeast facing slopes and coasts, particularly at night and during the mornign hours, while leeward areas see some shower development with the assistance of sea breezes each afternoon. Meanwhile, troughing aloft to the west of the state may allow for a slight enhancement to the shower activity, while also bringing considerable high cloudiness to the region. The broad trough west of the state will dampen out and shift westward Monday night and Tuesday. This will bring a resurgence of moderate to locally breezy east-northeasterly trade winds, and a more typical windward and mauka focused shower pattern. This pattern will then change little through the remainder of the work week, as strong high pressure persists to the northeast of the state. The trades may ease up and shift east-southeasterly again next weekend as another trough develops west of the area. Details on this remain unclear however, with the models split on how close this next trough manages to get to the islands chain. && .AVIATION... Breezy east-southeasterly trades expected today. Low cigs and SHRA should still have windward and mauka impacts with leeward areas getting in on a few SHRA as well. MVFR conds can be expected in heavier SHRA, otherwise VFR prevails. LLWS is exp this afternoon at HOG. AIRMET Sierra is in effect for mtn obsc for N thru SE sections of all islands. Conds should improve in the morning hours. AIRMET Tango is in effect for mod turb of all islands downwind of island terrain. With winds veering SE exp turb to move to the northwest of the islands. && .MARINE... Moderate to locally strong east-southeast trade winds will prevail through Monday. As a result, the Small Craft Advisory (SCA) has been extended for many zones around Maui and the Big Island through 6 PM Monday. The trades are expected to shift more east- northeast Monday night and Tuesday, and this will likely require a reconfiguration of the zones in the SCA along with an extension through late in the work week. The current northwest swell will decline today, with north shore surf dropping to near June average for the first half of the work week. Tiny surf is expected Thursday through next weekend. A mix of small background south swells will keep some small surf moving into south facing shores over the next couple days. A small southwest swell may bring a boost to south shore surf late Tuesday and Wednesday. A more significant long-period south-southwest swell will build late this week, then peak well above the June average next weekend. Surf along east-facing shores will remain small and choppy through Sunday, then gradually build to near or above seasonal average Monday through Wednesday due to a return of fresh to strong trades over and upstream of the islands. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST Monday for Maui County Windward Waters-Pailolo Channel-Alenuihaha Channel-Big Island Windward Waters-Big Island Leeward Waters. && $$ DISCUSSION...Jelsema AVIATION...Walsh MARINE...Jelsema