Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
962 FXHW60 PHFO 040122 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 322 PM HST Wed Sep 3 2025 .SYNOPSIS... Moderate trades deliver limited showers windward and mauka through Friday. Trade wind showers potentially increase over the eastern end of the state this weekend in advance of Tropical Cyclone Kiko which is poised to approach the Islands early next week. An associated flash flood threat will be possible. && .DISCUSSION... Mid-level ridge axis extending westward from 593dm mid-level ridging anchored east of the islands maintains strongly stable conditions today, particularly over the eastern end of the state. Water vapor provides a clear picture of the stability gradient currently in place with very dry mid-level air pivoting around the high and over Maui and the Big Island while lingering cyclonic flow aloft associated with low pressure west NW of Kauai supplies modest mid- level moisture over the western end of the island chain. The aforementioned mid-level high is displaced south in response to deep troughing advancing eastward over the NE Pacific. This in turn has suppressed the seasonably weak trade wind belt to the south resulting in moderate trades that will persist into early next week. Limited rainfall windward and mauka during this time owing to high stability and a lack of upstream moisture. The end of the forecast period will feature the passage of TC Kiko, which is presently moving quite slowly westward in the eastern Pacific Basin. The track of this cyclone will be governed by its intensity and interaction with steering flow, the latter of which will be modulated in part by deepening mid-latitude troughing near the islands as it approaches. For official forecasts of track and intensity, consult the National Hurricane Center. A flash flood threat may develop over the islands in the Tuesday-Thursday time frame conditional on the exact track of the system. && .AVIATION... Moderate trades expected for the next few days. A few low clouds and showers will be possible over windward slopes tonight, but MVFR conditions expected to prevail. No AIRMETS in effect or anticipated overnight. && .MARINE... A weak surface ridge to the north will remain nearly stationary through the weekend. This will maintain moderate to locally fresh trade winds with some localized sea breezes, especially across leeward waters. Tropical Cyclone Kiko, currently in the Eastern Pacific, is forecasted to move into the eastern waters early next week. Surf along north facing shores will continue to gradually decline through Thursday as a mix of the north and northwest swells fade. Reinforcing small short- to medium-period north-northwest swells are expected through the end of the week which will keep surf from going flat. In the extended forecast, the northwest Pacific looks to get active as low pressure systems traverse the basin over the weekend sending the potential for a few small to moderate swells during the middle of next week. Surf along south facing shores will see background medium- to long-period energy through the week before a small to moderate long-period south-southwest swell fills in and peaks over the weekend. Below average surf is expected to continue along east facing shores through the rest of the week. In the extended forecast, easterly energy from Tropical Cyclone Kiko is expected early next week. This will bring the potential for surf to reach High Surf Advisory criteria. Peak monthly high tides, combined with water levels running higher than predicted, may lead to minor flooding along the shoreline and in low-lying coastal areas. A Coastal Flood Statement remains in effect through Sunday afternoon. && .FIRE WEATHER... RH fell into the upper 30s at PHNL this afternoon and may fall to 45% or lower again during the next couple of days. However, winds will remain safely below threshold values as moderate trades prevail through the weekend. Limited rainfall anticipated during this time, though trade wind showers may increase in coverage over windward portions of the Big Island and Maui this weekend. TC Kiko is poised to pass over or near the islands early next week bringing potential for increased winds in addition to heavy rainfall. && .HFO WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...JVC AVIATION...Foster MARINE...Ahue FIRE WEATHER...JVC