Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
460 FXHW60 PHFO 112000 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 1000 AM HST Thu Jul 11 2024 .SYNOPSIS... Strong trade winds will persist into early next week, delivering abundant patches of low clouds most areas, while associated brief showers will mainly fall over windward areas. The Kona slopes will receive their typical summertime afternoon and evening clouds and showers. && .DISCUSSION... Breezy to windy trades will prevail into next week, supported by a persistent surface ridge far N of the islands. The ENE trade winds will deliver abundant patches of low clouds to windward areas (and occasionally leeward on the smaller islands), while associated brief showers will mainly fall over windward areas. The Kona slopes will receive their typical summertime afternoon and evening clouds and showers. A westward-moving mid-level trough just E of the area will weaken as it moves over the islands through Friday. Weak instability associated with this feature is the likely culprit behind the increased mixed-depth layer noted on the 12Z PHTO sounding and recent radar VAD wind profiles - up to 10 kft. This is allowing primarily stable low clouds to spread leeward, leading to conditions that are little more cloudy than expected. The trough will dissipate Friday night and Saturday, and the inversion base should lower enough to allow for more leeward sunshine over the weekend and into next week. Otherwise, randomly distributed clusters of stable and showery low clouds will periodically move through, modulating sky and shower coverage as they do so, mainly windward. && .AVIATION... Breezy to windy trades will continue for the next couple of days, with passing showers favoring windward and mauka areas. Expect mainly VFR, with brief MVFR in showers/low clouds. AIRMET Sierra for tempo mountain obscuration remains in effect for windward areas of Oahu, Molokai, and Maui. Conditions are expected to improve for these areas by this afternoon. AIRMET Tango for low-level turbulence in the lee of island terrain will remain in effect for the next several days due to the strong trades. Surface winds may briefly surpass 30kt, but these conditions are not likely to last long enough to need an AIRMET. && .MARINE... Persistent high pressure will remain in place north of the state through the weekend and into early next week. This will allow strong to near gale force trade winds to continue across the island chain, with only subtle day-to-day fluctuations. A Small Craft Advisory (SCA) remains in effect for all Hawaiian waters through Friday afternoon, but this will likely need to be extended through the weekend. The strong trades could ease slightly during the second half of next week as the ridge weakens. Surf along east facing shores will remain rough through early next week due to the strong trades locally and upstream of the state. A downward trend is possible next week as the upstream fetch weakens and the local trades begin to ease around midweek. Surf along south facing shores will remain up as overlapping south- southwest swells move through. A fresh south-southwest pulse arriving Friday will result in an upward trend in surf going into the weekend. A more significant south swell will gradually fill in late Saturday night into Sunday, then likely reach the advisory level late Sunday through Monday. A gradual downward trend is expected Tuesday through midweek. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST Friday for all Hawaiian waters. && $$ DISCUSSION...Birchard MARINE...Vaughan AVIATION...TS