Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
010 FXHW60 PHFO 220627 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 827 PM HST Fri Jun 21 2024 .SYNOPSIS... High pressure far north of the islands will maintain breezy and gusty trade winds through early next week. Somewhat wet conditions will give way to a more typical pattern of passing windward showers by Saturday afternoon. && .DISCUSSION... Breezy, gusty, and somewhat wet conditions are in place this evening. A 1030 mb surface high anchored about 900 miles north of the state is driving the breezy trade winds, and a mid-level ridge is maintaining stable conditions that are helping to produce wind gusts just below Wind Advisory strength over and downwind of terrain. Shallow moisture moving along the trade wind flow is producing somewhat wet conditions from Kauai to Maui this evening. The moisture will spread down to the Big Island overnight, and there should be quite a few windward sites on all islands that puck up between a half and one inch of rainfall through Saturday morning. Some of these showers will be periodically carried over leeward areas. The gusty trades will persist on Saturday nearly unchanged, meaning some areas across the Big Island and Maui County will register winds near or just below the advisory level. All islands except the Big Island will experience a decrease in shower activity as moisture within the trade wind flow diminishes. The strong surface high will remain anchored north of the state Sunday through at least Monday, maintaining the breezy and gusty trade winds near current strength. A stable and rather typical summertime rainfall pattern will prevail, leading to modest rainfall over windward slopes. Aside from afternoon showers on the Kona slopes of the Big Island, leeward areas will be mostly dry. Trades will decline to moderate strength around Tuesday or Wednesday as the high to the north finally weakens. Some increase in showers will be possible late next week. && .AVIATION... Breezy to locally windy trades will continue across the region for the next few days. A band of clouds drifting in on the trade winds will bring showers with periods of MVFR conditions to windward mountain slopes of each island at least through the early morning hours. AIRMET Sierra remains in effect for tempo mountain obscuration for north and east slopes of Kauai, Oahu, Molokai, and Maui. This AIRMET will likely expand to the Big Island later tonight. AIRMET Tango remains in effect for mod low level turb over and downwind of island terrain due to the breezy trade winds. This AIRMET will likely continue through the weekend. && .MARINE... Strong easterly trades will continue into early next week, supporting the Small Craft Advisory in place for all waters. Seas will remain rough, with heights hovering around and just under the advisory level over exposed waters. Guidance shows a slight downward trend Tuesday through midweek due to the surface ridge potentially weakening to the north. Surf along east-facing shores will remain rough through early next week due to the aforementioned strong trades locally and upstream of the state. A gradual downward trend is possible Tuesday through midweek. Surf along south-facing shores will trend up slightly this weekend as a small south swell moves through. This should be short-lived, with a downward trend expected early next week. Despite a blocking high that has set up over our typical swell window near/southeast of New Zealand, a gale has formed to its northeast with the head of the fetch aimed at the islands within the 180 to 200-degree directional band. Given the shorter travel distance, surf associated with this source should trend up late next week. Surf along north-facing shores could trend up above flat levels early next week due to a small, medium-period northwest swell from a marginal gale lifting northeastward near the Aleutians. On its heels is a compact storm-force low, currently a few hundred nautical miles east of Japan, that could send a similar northwest swell through the area late next week. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST Sunday for all Hawaiian waters. && $$ DISCUSSION...Wroe AVIATION...Bohlin MARINE...Gibbs