Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
143 FXHW60 PHFO 141912 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 912 AM HST Mon Sep 14 2026 .SYNOPSIS... Relatively dry and weak trades will gradually strengthen through Wednesday, then become moderate through next weekend. Moisture from the remains of Norbert should arrive Thursday into Friday, greatly increasing shower coverage and intensity. Drier air will move back in next weekend as trades continue. && .SHORT TERM UPDATE... No significant changes to the forecast for this morning with only a minor nudge to blended model. Expecting to have increasing showers today and Tuesday as tropical moisture moves across the state. Light trades will focus clouds and showers windward at night and in the morning, with localized sea breezes resulting in interior clouds and showers over the next couple of days. && .PREV DISCUSSION... Issued at 403 AM HST Mon Sep 14 2026 This morning`s satellite imagery shows a band of moisture east of the Big Island, which will be moving east to west across the state today. 12Z soundings from Lihue and Hilo show a stable trade wind inversion at around 5000 to 6500 ft. While stable conditions are expected to persist over the next few days, the increase of moisture will bring an increase of humidity and some light to moderate showers over windward and mountain areas. Dewpoints are expected to get into the 70s by late Monday into Tuesday, which will bring some muggy weather across the state. Starting Wednesday and continuing through Friday, the weather pattern will change as the remnants of Norbert moves east to west across the state. Deep tropical moisture from Norbert combined with a weak upper level trough will bring an increase of heavy showers especially by Thursday. With trades picking up to moderate to breezy speeds by late Wednesday into Thursday, the focus of the heavy rain will be over windward and mauka areas. A Flood Watch may be warranted especially for Thursday into Thursday night, but we will wait to see what the high res models show as we get closer to the second half of the week. So overall we are expecting a wet, trade wind pattern during the second half of the week with the focus of the heavier showers over windward and mauka areas. While leeward areas should see some frequent showers, in areas with less shower activity can expect hot and muggy weather, with dewpoints getting up into the mid 70s. Over the weekend, while the bulk of the deep tropical moisture should move west of the state, showery weather could linger through at least parts of Saturday. But generally improving weather conditions are expected this weekend with moderate to breezy trade winds. && .AVIATION... We will see a slight uptick in moisture with the trade winds today, leading to a 30-70% chance of showers on the windward side of the islands. Radar imagery this morning continues to show showers drifting westward over our waters with a few showers passing over the islands. MVFR conditions are expected with shower activity today, with cloud heights around 2000-2500. The forecast should be on repeat for Tuesday, as moisture continues to gradually increase. For PMDY conditions look to remain dry, though we may get a few low to mid level clouds due to a low sitting north-northeast of the region. Opted to continue to keep the forecast dry through most of today, though the ECMWF model shows the potential for some passing showers later this afternoon. Both the GFS and the ECMWF show showers late tonight into Tuesday, with winds shifting to the north or northwest. && .MARINE... Issued at 403 AM HST Mon Sep 14 2026 Moderate to locally fresh trades will continue through Tuesday before strengthening through the latter half of the week. Moisture associated with a weak trough moving in on the trade wind flow may bring a slight uptick in shower activity today into Tuesday. Wednesday night, the remnants of Tropical Storm Norbert enter the offshore waters and are forecast to bring a more significant increase in moisture and stronger trade winds Thursday into the weekend. Surf along south-facing shores will be slightly below seasonal average through Tuesday. A series of long-period swells are expected during the second half of the week. The first pulse will gradually fill in tonight into Wednesday out of the southwest, followed by larger south-southwest swells Friday into the weekend. Surf gradually trends upward through the week beginning Wednesday and will approach advisory thresholds by the weekend. Surf along east-facing shores should see an increase during the second half of the week as the trades strengthen and the remnants of Tropical Storm Norbert move through the islands. Flat to tiny surf along north facing shores is expected through the forecast period. && .FIRE WEATHER... Issued at 403 AM HST Mon Sep 14 2026 Fire weather risk will remain low throughout this week due to light to moderate trade winds the next few days followed by a wet trade wind pattern during the second half of the week. Inversion heights should be around 5000 to 7000 ft through Tuesday due to stable conditions. && .HFO WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM UPDATE...Foster PREVIOUS DISCUSSION/FIRE WEATHER...Kino AVIATION...LP MARINE...Quesada