Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
084 FXHW60 PHFO 200636 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 835 PM HST Wed Jun 19 2024 .SYNOPSIS... Persistent 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 afternoon`s soundings is anchored between 5 and 6kft, translating into stable low clouds that are delivering limited 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. Those keen to the subtleties in island weather may have noticed ice crystals precipitating from the associated high-level clouds based around 20 kft near Kauai and Oahu. Little change is expected during the next 24 hours as highly stable and breezy trades persist. Thereafter, trades get a modest boost as the pressure gradient strengthens over the area, with locally strong trade winds then continuing into the weekend. At the same time, increased PWAT will arrive late Thursday night marking the onset of a somewhat wetter trade wind pattern, with increased dew points (low 70s) 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. The summer solstice will occur at 1051 AM HST Thursday June 20th, marking the astronomical start of summer. The moon will be full at 308 PM HST Friday June 21st. && .AVIATION... Breezy to locally windy trade winds will persist through the next couple of days and usher in bands of light showers to the island chain`s windward areas. Isolated spillover showers will be possible along leeward slopes, especially in the late night and morning hours. A weak eddy just west of the Big Island may keep the Kona coast covered in clouds through late tonight. As shower coverage increases slightly overnight, low ceilings and visibilities could redevelop along windward slopes late tonight or Thursday morning, with a focus near the big island. Elsewhere, VFR conditions will prevail except for brief MVFR conditions in passing 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 remains in effect for most waters around the Big Island and Maui County and will expand to most waters as the trade winds 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 is currently at 6 to 7 feet at 7 to 8 seconds and will rise slightly with increasing wind speeds this weekend. Surf along north facing shores will be at seasonally tiny levels 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 Kaiwi Channel- Maui County Windward Waters-Maalaea Bay-Pailolo Channel- Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...Birchard AVIATION...Farris MARINE...Bohlin