Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
717 FXHW60 PHFO 301343 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 343 AM HST Mon Jun 30 2025 .SYNOPSIS... Light trades will prevail and veer east-southeast slightly through the next couple of days in response to broad and weak surface trough. Shower activity will primarily impact typical windward and mauka areas, however localized sea breezes will increase showers to leeward and interior areas throughout today. Toward mid-week, trades shift back easterly, gradually increasing in strength into the weekend. && .DISCUSSION... A broad, positive-tilted surface trough passing to the north of the islands will be the culprit to weaker trades the next few days. As trades decrease in strength and veer slightly east- southeast, expect land-sea breezes to develop across select areas as a response. Additionally, as the trough remains present in vicinity of the islands, shower activity will likely increase as well, predominately across windward and mauka areas, but may stray into leeward and interior areas as well where afternoon sea breezes develop in the lighter wind flow. Any significant increase in shower activity will be hindered by a midlevel inversion at around 8000 feet. As the aforementioned trough exits by the mid-week, as will the increased shower activity. The surface high well northeast of the islands will gradually build, leading to a return of moderate to locally breezy trades across the state. During this time, expect drier conditions and less cloud coverage, however, pockets of moisture escorted by these trades will lead to periodic showers across windward and mauka areas. Latest model guidance of the GFS and Euro remains in good agreement that trades will steadily increase across the state to breezy to locally strong into the weekend through early next week. While stronger trades typically result in an increase in passing showers, latest guidance suggests that shower activity will remain modest at best, given atmospheric stability aloft. && .AVIATION... Clouds and showers are expected to prevail through much of the day over leeward and interior sides of the islands due to sea breeze convergence. Otherwise, expect passing showers over typical windward and mountain areas. Brief periods of MVFR conditions likely with any showers, but overall VFR conditions should prevail. No AIRMETs are in effect at this time. && .MARINE... A trough located far to the north along with weakening surface high pressure to the northeast will contribute to weakening trade winds over the next few days. A slight southerly component to the winds is expected today as the trough to our north lingers. Winds should then become easterly and remain in the moderate to locally fresh range Tuesday through midweek as the trough weakens and dissipates. Trade winds should strengthen by Independence Day into the weekend as high pressure builds to the north. Surf along south facing shores will see a small, long-period south swell fill in and hold today and tomorrow with surf peaking near the summertime average. Surf heights will then gradually lower late tomorrow through the week as the swell slowly declines, however small pulses will keep surf heights from falling flat. A smaller long- period south swell could move through toward the end of this week for a slight boost to south shore surf. Surf along east shores will remain small over the next several days due to the trade winds weakening, then could increase towards the end of the week as trade winds strengthen. Surf along north facing shores will remain seasonally tiny through the week. && .HFO WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Pierce AVIATION...Pierce MARINE...Tsamous