Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
616 FXHW60 PHFO 301900 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 900 AM HST Sun Aug 30 2026 .SYNOPSIS... Moderate to breezy trades will continue through at least the middle of next week. Showers will generally favor windward and mauka areas, particularly during the overnight through early morning hours each day. Tropical Storm Lowell remains far ESE of the main Hawaiian Islands, and uncertainty regarding its track and intensity forecast is high at this time. && .SHORT TERM UPDATE... Benign trade wind pattern through at least Wednesday and probably Thursday as strong longwave ridging approaching 594dm remains anchored near 170W longitude before migrating east during the latter portion of the week. This in turn favors expansive surface high pressure in maintenance of breezy trades through this time. An uptick in showers for windward and mauka is expected next week as moisture originating off the California coast entrains in the trades, reaching the islands around Wednesday. The tropics remain active with attention turning toward the Friday Sept 4th (Day 5) to Wednesday Sep 9th (Day 10) period. During this time, uncertainty runs considerably higher than normal owing to weak steering flow followed by potential emergence of a closed upper low NW of the islands that will alter steering flow and introduce a component of shearing as well. TC Lowell and TC Karina both carry potential to come precariously close to the islands during this time window. Guidance regarding both systems is plagued with the same uncertainty for the same reasons, so potential outcomes unfortunately remain wide open despite the decreasing lead time. It is worth noting that machine learning guidance remains supressed fairly far south with Lowell and the 12z ECMWF has trended strongly in this direction. Consult NHC for the official track and intensity forecast. && .PREV DISCUSSION... Issued at 415 AM HST Sun Aug 30 2026 A 1034 mb high far north of the state will continue to produce breezy conditions across the state today. Latest radar and satellite imagery is showing some scattered light showers riding in with the breezy trades early this morning. Shower activity should generally trend down throughout the day today with mostly dry conditions expected this afternoon. Starting tonight, we should see a slight increase of showers move in with the breezy trades due to a subtle increase of low level moisture. Some passing showers will likely linger across windward and mauka areas through Monday with a few light showers possible over leeward areas as well. Tuesday and Wednesday will also be fairly similar to Monday with some passing showers over windward and mauka areas. Trades may briefly weaken slightly late Tuesday into Wednesday. For the second half of this week, the weather forecast for Hawaii will be dependent on the track of T.C Lowell. Currently Lowell is a Tropical Storm located near 13N139W and is expected to strengthen into a Hurricane over the next few days. The latest forecast track from the National Hurricane Center (NHC) has Lowell passing around 300 miles south of the Big Island Thursday morning. While the 00Z run from the ECMWF and the 06Z run from the GFS show a slower track but a closer track to the state. The 06Z run from the better performing GDM model shows it further south (roughly 400 miles south of the Big Island) than the official track. So as you can see, there is a lot of spread in the forecast models, thus it is too early to predict any potential impacts to Hawaii at this time. While it is too early to predict any impacts, it is looking likely that we will see windier weather towards the end of this week. How strong the winds will be is yet to be determined... && .AVIATION... Issued at 415 AM HST Sun Aug 30 2026 Conditions will be mostly VFR. Trades will continue at breezy speeds, creating occasional turbulence downstream of mountains. In addition, showers will focus on windward sites, but should remain isolated. Low ceilings may occur briefly, but limited moisture should prevent sites from getting bogged down in long- lasting MVFR. AIRMET Tango is in effect for mod low-level turbulence lee of terrain and may be needed for a few days. && .MARINE... A strong surface high will remain nearly stationary far north of the Hawaiian Islands this week. Moderate to locally strong trade winds will prevail through the week. Tropical Cyclone Lowell may move into the Hawaiian Offshore Waters from Wednesday into Thursday. Wind and weather impacts and timing for the coastal waters will be driven by the speed and track of Lowell as it moves towards the region. The current south swell will slowly decrease over the next several days. Overlapping small, long- and medium-period south swell energy will keep small surf along south facing shores through the week. The next good boost in south swell energy will arrive and fill in from Tuesday to Wednesday at around 2 to 3 feet with an 18 second period. This swell will peak on Wednesday, just below south shore advisory thresholds, and then slowly decline through the end of the week. Trade wind swell energy will continue to keep elevated surf heights along all east facing shores this week. && .FIRE WEATHER... Issued at 415 AM HST Sun Aug 30 2026 We saw a fairly dry day across parts of the state yesterday with humidities getting down into the upper 30s for select leeward areas. Another breezy and dry day is expected today with humidities down into the low 40s and possibly upper 30s again for a few leeward areas this afternoon. While fuel conditions do not remain critical at this time due to the abundant rainfall we received over the past several weeks, moderate fire danger will be possible for areas that have not received much rainfall over the past few weeks. An increase of showers and humidities is expected tonight into Monday. While the passing showers should be confined to mainly windward and mauka areas, some higher minimum humidities is expected for Monday. Soundings show the temperature inversion between 5000 to 6000 feet today. We should see the inversion rise to 6000 to 7000 feet on Monday. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST this evening for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Big Island Windward Waters-Kaiwi Channel-Kauai Channel-Kauai Leeward Waters-Kauai Northwest Waters-Kauai Windward Waters- Maalaea Bay-Maui County Leeward Waters-Maui County Windward Waters-Oahu Leeward Waters-Oahu Windward Waters-Pailolo Channel. && $$ SHORT TERM UPDATE...JVC DISCUSSION...Kino AVIATION...Parker MARINE...TS FIRE WEATHER...Kino