Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
996 FXHW60 PHFO 140147 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 347 PM HST Tue Aug 13 2024 .SYNOPSIS... Persistent high pressure far north of the islands will support locally breezy trade winds into next week. Passing showers will periodically dampen most windward areas, with some showers occasionally spreading leeward, especially night and morning. && .DISCUSSION... Persistent surface high pressure far north of the islands will support locally breezy trade winds for the foreseeable future. A trough aloft will maintain just north of the islands over the next couple days and will bring some modest mid-level cooling and weakening the subsidence inversion. This will allow orographic lift to produce a few moderate showers, in addition to light passing showers arriving on the trades. These showers will primarily impact windward sides and occasionally reaching leeward sides. The overall pattern looks a bit drier than normal through Wednesday afternoon as a slightly drier airmass passes. A low- level trough approaching from the east (remnants of former T.S. Emilia) is forecast to dampen out as it reaches the longitude of the islands Wednesday night through Thursday night. Trade winds will weaken slightly as the trough moves across the islands but strengthen Friday as it tracks away to the west. A mid-level ridge will rebuild over the islands by the weekend, likely reducing shower coverage/frequency. Breezy trades will linger into next week along with a drier airmass from Friday onward. Possible moisture from passing troughs south of the Big Island could bring additional showers to the southern end of the state next week. && .AVIATION... Moderate to locally breezy trade winds will deliver clouds and showers mainly to windward and mountain areas through the next few days. Showers will favor the night time hours and will bring brief MVFR cigs and visibilities. Overall VFR conditions will prevail. No AIRMETs are currently in effect however an AIRMET sierra for mountain observation may be needed later in the evening with the night time shower enhancement. && .MARINE... An area of surface high pressure north of the state will remain nearly stationary over the next several days and produce moderate to locally strong trade winds across the local waters. A brief weakening of the trades is possible late Wednesday into Thursday morning as a weak trough passes north of the state. A Small Craft Advisory (SCA) remains in place through Thursday morning for the typically windier waters around Maui County and the Big Island and will likely need to be extended through the weekend. Several small long-period swells from the south and southeast will produce some small surf along south facing shores throughout the week. A Gale force low east of New Zealand tracked northward with the main fetch aimed at Hawaii during the past 36 hours. OSCAT data showed a wide fetch of 30 to 35 knot winds with pockets of 40 knot winds during its peak with altimeter heights of up to 29 feet. This swell should slowly fill in next Sunday and peak on Monday above the summer average. Seasonally flat to tiny surf is expected through this week for north facing shores. Breezy trade winds will continue to produce rough and choppy surf along east facing shores with a slight decrease expected during the next few days. The combination of the full moon and water levels running around 0.5 ft higher than normal should produce minor coastal flooding each afternoon along the shorelines across the state beginning 8/17 and likely continuing through 8/20. A Coastal Flood Statement will eventually be needed as we get closer to the event. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 AM HST Thursday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...Foster AVIATION...Tsamous MARINE...Kino