Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
677 FXHW60 PHFO 071949 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 949 AM HST Fri Jun 7 2024 .SYNOPSIS... Light to gentle easterly trade winds will develop today as a ridge meanders just north of Kauai. Over the weekend the ridge will lift northward, allowing trade winds to gradually strengthen. Moderate to locally breezy trade wind conditions are expected by Sunday, and persist into the middle of the new week. Very stable conditions will greatly limit shower activity through the weekend, with a slight increase in windward showers expected Monday and Tuesday. A more typical trade wind pattern should return by the middle of next week. && .DISCUSSION... This morning visible satellite image shows a shallow cloud deck riding in with gentle easterly trade winds over the Big Island with some clouds forming along windward areas of the smaller islands. Leeward locations are generally sunny except for leeward Big Island where sea breezes have developed and clouds are moving in along the coast. Expect some clouds to build up along other leeward coast and interior areas through the afternoon as sea breezes continue to develop under this hybrid trade wind and land/seabreeze wind regime. Based on this morning soundings, inversion heights remain abnormally low around 3 kft. Chances of rainfall will remain low as very stable conditions persist. The ridge will begin to lift northward over the weekend, which will allow the trades to gradually return from south to north. Moderate to locally breezy conditions are expected by Sunday and persist into the middle of next week. Clouds and showers will return to the more typical windward and mauka areas, however shower activity will remain limited across the entire state over the weekend due to very stable conditions from low inversion heights. The trade wind inversion will begin to lift early next week, which should bring a slight increase in trade wind showers Monday and Tuesday, but will still remain drier than normal for this time of year. A more typical trade wind pattern should return during the middle to latter half of the week with rising inversion heights. && .AVIATION... A weak pressure gradient across the region will maintain light trade winds across the state with daytime sea breezes developing by mid morning especially over the leeward areas. Shower activity will continue to remain limited due to a strong ridge of high pressure aloft. A few light showers will be possible during the afternoon mainly over interior and leeward areas and the Kona slopes of the Big Island. With the strong inversion, ceilings will be quite low with any clouds, which will allow for periods of MVFR conditions. AIRMET Sierra is in effect for tempo mountain obscuration for leeward sections of the Big Island and windward Oahu. These conditions should generally improve by around mid day as the sea breezes develop. && .MARINE... A weak elongated ridge in the northern offshore waters will hold in place over the region. Expect wind speeds to remain below Small Craft Advisory (SCA) threshold through Saturday. High pressure will redevelop north of the state over the weekend, allowing moderate trade winds to build back. Models show the potential for SCA conditions across typical windier waters around Maui County and the Big Island by Sunday. The current south-southwest swell will peak today and steadily decline through the weekend. That said, morning observations show this swell is producing surf up to High Surf Advisory (HSA) threshold along south facing shores, prompting issuance of an HSA valid through tonight. A bigger moderate long period south- southwest swell will build through Saturday, peak Sunday night into Monday and could generate surf at or above HSA threshold once again at the peak. Yet another long period south swell may generate HSA threshold surf late next week. The current small northwest swell continues to decline. However, a reinforcing pulse from the northwest will build in late this afternoon to give north facing shores a small bump. Wind waves for east facing shores have diminished significantly and will remain small into the weekend. && .HFO WATCHES/WARNINGS/ADVISORIES... High Surf Advisory until 6 AM HST Saturday for all south facing shores. && $$ DISCUSSION...Almanza AVIATION...Kino MARINE...Powell