Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
254 FXHW60 PHFO 191937 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 937 AM HST Sat Sep 19 2026 .SYNOPSIS... Moderate to locally breezy trade winds will continue through Monday before gradually declining by midweek. Another round of enhanced moisture will arrive by next Tuesday, which should increase shower activity statewide. && .SHORT TERM UPDATE... No updates to the forecast this morning. High clouds will dominate the skies over the eastern end of the state. Muggy conditions to continue with dewpoints remaining in the low 70s. Not expecting any significant changes to the forecast with the afternoon package. && .PREV DISCUSSION... Issued at 305 AM HST Sat Sep 19 2026 Satellite and radar imagery shows some windward and mauka showers ongoing across the state. An increasing trend in stability and relatively drier air will begin this weekend, which will limit shower activity and coverage to windward and mauka areas. Kona slopes of the Big Island may still see some afternoon showers through the weekend, with a small chance of thunderstorms upslope due to lingering instability. Confidence is low so have not introduced thunderstorms into the forecast. Trades will continue to be moderate to locally breezy through Monday, but are expected to gradually decline by midweek. Another influx of moisture associated with the remnants of Tropical Depression 15-E is expected to arrive by Tuesday and potentially remain through Thursday. PWATs could reach up to 2.5" over the southeastern portion of the state according to global models, which is above seasonal normal. A shortwave is also expected to be within the vicinity of the islands during this time period, which could lead to some enhanced showers. The long term forecast will also be dependent on how models handle the remnants of Tropical Depression 15-E. Environmental conditions are conducive for some development next week according to the NHC. Given the chance for this forecast to change, please continue to monitor the status of tropical cyclone development through nhc.noaa.gov, and local weather forecasts at weather.gov/hfo. && .AVIATION... Breezy trades will persist through the weekend and focus clouds and isolated to scattered showers over windward and mountain areas. This morning, clouds and showers have most consistently been funneled across windward Kauai and the area around Hilo on the Big Island, bringing MVFR and even brief IFR conditions. AIRMET Sierra is in effect for tempo mountain obscuration for these areas until conditions are expected to improve later this morning or afternoon. In addition to the windward shower activity, the Kona slopes of the Big Island could see some afternoon showers or even an isolated thunderstorm or two, though thunderstorm chances are low. AIRMET Tango remains in effect for moderate low-level turbulence downwind of island terrain due to the breezy trade winds. This AIRMET will likely be needed through much of the weekend. && .MARINE... Issued at 305 AM HST Sat Sep 19 2026 High pressure will remain to the northeast, therefore moderate to locally strong trade winds will continue through at least the first half of next week. A Small Craft Advisory is in effect for the typical windy waters around Maui County and Big Island through Saturday, and will likely be extended into early next week for these waters. A trough could move into the area next week. Surf along south-facing shores will remain above average through the weekend as long-period south-southwest swell holds today. Then another south swell will build in today and both swells will decline gradually next week. A smaller long period swell could fill in late next week. Moderate surf along east-facing shores will persist over the next several days as fresh to locally strong trades continue. Surf along north-facing shores will remain flat to tiny, with a minor bump possible Tuesday into Wednesday next week. Then a small long period west-northwest swell swell could build in late next week. && .FIRE WEATHER... Issued at 305 AM HST Sat Sep 19 2026 Fire weather risk remains low due to residual moisture from the remnants of Norbert. Moderate to locally breezy trade winds are expected through Monday, and should filter in some relatively drier air for that time period. Inversion heights are around 6500 and 8000 feet. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST this evening for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Maalaea Bay-Pailolo Channel. && $$ DISCUSSION...Walsh AVIATION...Farris MARINE...Tsamous FIRE WEATHER...Walsh UPDATE...M Ballard