Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
958 FXHW60 PHFO 190122 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 322 PM HST Tue Jun 18 2024 .SYNOPSIS... Ongoing breezy and dry trades will turn locally strong and become somewhat wetter Thursday into the weekend. && .DISCUSSION... The sharp trade wind inversion around 5kft on this afternoon`s soundings highlights the stable pattern in place over the forecast area. This is in spite of an upper low positioned directly overhead, which is doing little more than producing periodic patchy high clouds, a testament to existing strong mid-level stability. Low- level water vapor imagery shows an even drier appearance to the upstream airmass suggesting stability will further strengthen during the next 24-48 hours. During this time, breezy trades will continue delivering shallow and mostly light shower activity windward and mauka as has been the case for the last couple of days. Meanwhile, troughing along the US West Coast is seeding the upstream trade wind environment with increased moisture that is poised to arrive during the latter half of the week. Model consensus remains in tact that trades will become locally strong while also acquiring a wetter character Thursday night into the weekend. Showers will occasionally drift into the typically drier leeward zones, mainly overnight and during the early morning, as deeper moisture forces the inversion to lift and weaken. && .AVIATION... Breezy trades will continue, with SHRA and low cigs favoring windward and mauka locations. Periods of MVFR conds are possible in any SHRA. Otherwise, VFR conds should prevail. Trade winds are expected to slightly strengthen to locally strong speeds during the next 24 hours. AIRMET TANGO is in effect for low level turbulence lee side of mountains due to the strengthening trade winds. A weak upper level low is producing light to moderate turbulence between 160 and FL340. AIRMET SIERRA could make its return tonight as clouds and showers move into windward areas. && .MARINE... Fresh to strong trade winds will persist for the next couple of days as a 1026 mb surface high strengthens and drifts around 700 to 800 nm northeast of the state. A Small Craft Advisory (SCA) is in effect for most waters around the Big Island and Maui County. As the high settles far north of the islands Thursday and Friday, trade winds will increase a notch, bringing near gale conditions and elevated seas in some channels. The SCA will likely be expanded to most waters at that time and continue through the weekend. The current south swell will fade out tonight, followed by a lull in south shore surf into Friday. A mix of small, long-period south swell and a shorter period southeast swell may push shores up near seasonal average during the weekend. As these swells slowly decline early next week, another long-period south- southwest swell is expected to fill in. Surf along east-facing shores will gradually trend up Thursday through the weekend. The trade wind swell is currently just under seasonal average at about 6 to 7 feet at 7 to 8 seconds. Expect a slight increase late Wednesday or Thursday, followed by a rise above seasonal average this weekend. Surf along north-facing shores will return to seasonally tiny levels tonight as a small northwest swell fades. Additional very small pulses are possible Thursday and again early next week. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST Thursday for Kaiwi Channel- Maui County Windward Waters-Maalaea Bay-Pailolo Channel- Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...JVC AVIATION...Kino MARINE...Wroe