Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
358 FXHW60 PHFO 040606 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 806 PM HST Mon Jun 3 2024 .SYNOPSIS... Breezy trades will continue through Tuesday, before easing Wednesday and giving way to sea and land breezes Thursday and Friday. A fairly typical trade wind pattern will continue through Tuesday morning, with trade wind showers then steadily decreasing through the middle of the week as a more stable airmass gradually settles overhead. Some lingering instability may allow for a thunderstorm to pop over interior Big Island Tuesday afternoon however. Very dry conditions will overspread the entire island chain Thursday through the weekend, greatly limiting shower activity across the entire state. Returning and gradually strengthening trade winds could bring a slight increase in showers early next week. && .DISCUSSION... Currently at the surface, a 1028 mb high centered 950 miles northeast of Honolulu, is driving breezy trade winds across the island chain. Infrared satellite imagery shows partly to mostly cloudy conditions with cloud cover most prevalent over windward and mauka areas. Radar imagery shows isolated to scattered to showers affecting windward slopes and coasts, with the occasional shower spilling Leeward at times. Main short term focus revolves around trade wind trends and rain chances. The high to the northeast of the islands will remain nearly stationary through Tuesday, slowly weaken as it shifts eastward on Wednesday, with the ridge axis then moving over or very near the western islands Thursday and Friday. Breezy trade winds will continue through Tuesday, then ease into the moderate range Wednesday. The winds will ease further and become light and variable over the smaller islands Thursday and Friday, allowing for daytime sea breezes and overnight land breezes to be dominant. Meanwhile, light trades will likely hold in the unprotected areas of the Big Island. The surface ridge axis is forecast to shift northward over the weekend into early next week, which should bring a return and gradual strengthening of the trade winds. As for the remaining weather details, a very unstable airmass aloft will remain over the islands tonight, and this may allow for a few high based thunderstorms to move into the windward waters over the eastern end of the state. Otherwise, fairly typical trade wind weather should prevail tonight into Tuesday morning. The trade wind inversion is then expected to crash down to around 5 kft greatly limiting trade wind showers Tuesday afternoon. There remains a slight chance that instability aloft could allow a thunderstorm to pop over the Big Island interior during the afternoon hours, but as was the case today, dry air aloft may prove to much for the convection to overcome. Rather dry trade wind weather will continue Tuesday night through Wednesday night as the trade wind inversion holds around 5 kft, with most leeward areas not seeing any rain. Little change in the trade wind inversion height is expected Thursday through the weekend, greatly limiting shower activity across the entire state. A slight increase in windward showers is possible late in the weekend into early next week as the trades gradually return and inversion heights begin to slowly rise. && .AVIATION... Breezy to locally strong trades will produce low cigs and SHRA in windward and mauka zones through the period. Nothing more than isolated MVFR expected. The arrival of elevated instability favors a chance for isolated TS over interior and upslope sections of the Big Island Tuesday afternoon. AIRMET Sierra will go into effect at 10Z for mtn obsc for windward Big Island and N thru SE sections of the smaller islands. AIRMET Tango for lee turb remains in effect. && .MARINE... Broad high pressure north of the state will maintain fresh to strong trade winds into Tuesday, and a Small Craft Advisory (SCA) remains in effect for all waters around the Big Island and Maui County and select areas around Oahu and Kauai. The ridge will continue to weaken as the SCA will likely be trimmed back to the typical windy waters around Maui County and the Big Island Tuesday night and Wednesday. The ridge further erodes and displaces the ridge southward over the islands Thursday into Friday, causing the trades to diminish significantly and possibly become disrupted. The SCA will be dropped completely by this time. Increasing moderate trades are expected during the weekend as the ridge lifts northward. An active south Pacific will continue the extended run of southerly swell almost certainly through mid June. The current south-southwest swell has peaked and remains steady just below High Surf Advisory Criteria. This swell will gradually decline Tuesday into Thursday, followed by a reinforcing south- southwest swell late Thursday and Friday that will produce south shore surf around seasonal average. Coming into the weekend, a larger swell will move through the islands likely near or at the High Surf Advisory (HSA) criteria of 10 feet. Followed by a potentially larger swell in development looking increasingly likely to push surf well above the advisory level late next week. A small northwest swell has continued to build this evening and will peak late tonight and Tuesday, then linger into Thursday. A possible small short- period north- northwest swell should follow later in the week. The fresh to strong trade wind flow is producing rough choppy elevated seas. Wind waves will diminish significantly after Wednesday coinciding with the light winds through the weekend. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST Tuesday for Kauai Northwest Waters-Oahu Leeward Waters-Kaiwi Channel-Maui County Windward Waters-Maui County Leeward Waters-Maalaea Bay-Pailolo Channel- Alenuihaha Channel-Big Island Windward Waters-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...Jelsema AVIATION...Walsh MARINE...Shigesato