Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
123 FXHW60 PHFO 201315 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 315 AM HST Thu Jun 20 2024 .SYNOPSIS... High pressure far north of the islands will support locally strong trade winds through the weekend. Brief, passing showers will favor windward areas, especially during nights and mornings, with a few sprinkles occasionally spreading leeward. && .DISCUSSION... Seasonably benign trade wind weather will continue through the forecast period. A strong subsidence inversion on this morning`s soundings is a little higher than yesterday (between 7 and 8 kft), but continues to translate into stable low clouds that are delivering a few showers to windward and mauka zones. Instability and moisture aloft associated with a mid- and upper-level low W of Kauai is also noted in the Lihue sounding. Locally strong trade winds will continue through the weekend, with potential for some modest easing in trade wind speeds next week as the high to the N moves NE. Increased PWAT arriving early Friday will mark the onset of a somewhat wetter trade wind pattern, with increased dew points also making it feel more humid. The upper low over the area will slowly drift westward, funneling periodic high clouds into the area for the next several days. Today is the longest day of the year in the northern hemisphere, with the summer solstice occurring at 1051 AM HST this morning. && .AVIATION... Breezy to locally strong trade winds will persist through the next couple of days and usher in bands of showers to the island chain`s windward areas. Isolated spillover showers will be possible along leeward slopes, especially during the late night and early morning hours. VFR conditions will generally prevail except for in passing showers where brief MVFR conditions will be possible. AIRMET Sierra is in effect for mountain obscuration across windward areas through the morning due to low clouds and showers. AIRMET Tango remains in effect for low level turbulence lee of mountains due to the breezy trade winds. && .MARINE... Fresh to strong trade winds will increase through Friday as a high pressure system to the north-northeast strengthens and settles about 800 nm north of the islands. A Small Craft Advisory was expanded this morning to include all Hawaiian coastal waters as trade wind speeds increase. Fresh to near-gale winds will hold through the weekend and likely into early next week. Expect minimal south shore surf into Friday. A mix of a small, long- period south swell and a shorter period southeast swell may push surf close to seasonal average during the weekend. As these swells slowly decline early next week, another small, long period south- southwest swell is expected to fill in. Surf along east facing shores will gradually trend up during the weekend. The trade wind swell will rise slightly with increasing wind speeds this weekend. Surf along north facing shores will remain small through much of the week, with very small pulses of northwest swell possible into early next week. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST Saturday for all Hawaiian waters. && $$ DISCUSSION...Birchard AVIATION...Farris MARINE...Bohlin