Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
584 FXHW60 PHFO 281754 CCA AFDHFO Area Forecast Discussion...CORRECTED National Weather Service Honolulu HI 754 AM HST Thu Aug 28 2025 .SYNOPSIS... Low pressure north of the islands will remain embedded in a broad, quasi-stationary area of high pressure for the next several days, resulting in a hybrid sea breeze and moderate trade wind pattern. Hot and dry conditions will prevail with little to no rainfall expected. && .DISCUSSION... A surface low and its associated trough remain embedded within a broad, quasi-stationary high pressure ridge northeast of the islands. Trades will persist into the light to locally moderate speed range through early next week, as a result. Additionally, the atmosphere will remain very stable heading into next week, courtesy of the aforementioned broad high pressure ridge. This is evident in the 12Z soundings from Hilo and Lihue this morning, with strong temperature inversions around 6,000 to 7.000 feet. Moreover, expect hot and dry conditions to continue through the weekend and into early next week as rainfall producing shower activity will be extremely limited across the state. Trade speeds reduce even more this weekend into early next week, resulting in a more widespread hybrid sea breeze and trade wind pattern, likely enhancing leeward and interior region cloud buildups in the afternoons. However, little to no precipitation is expected from any showers that do develop as a drier airmass consumes much of the region. Furthermore, afternoon temperatures are progged to be quite high throughout the forecast period; upwards of 90 degrees in some areas, which could pose some elevated fire weather concerns (see latest fire weather section). The latest deterministic model guidance from the GFS and ECMWF remains in good agreement that the aforementioned surface low and associated trough will eventually lift northward next week. This will open the door for high pressure to rebuild and may result in trades strengthening a bit around the middle of next week. && .AVIATION... A hybrid sea breeze and light to locally moderate trade wind pattern will prevail today and persist through the next several days. Periods of MVFR conditions will briefly affect windward slopes, and aside from isolated pockets of afternoon MVFR ceilings on leeward terrain, VFR will dominate over most leeward sections. No AIRMETs are in effect and none are expected. && .MARINE... A weak trough embedded in the broader ridge north of the islands will keep gentle to locally fresh trades blowing through the weekend. Trade wind speeds might increase back to more typical levels by the middle of next week. A small, long period south swell continues to slowly fill in with yet another reinforcing pulse building into the region later today. South swell energy will peak on Friday with surf heights along south facing shores near the summer averages before declining over the weekend. A smaller portion of this long period south swell energy will wrap around into west facing shores. Surf heights will return to background levels early next week along south facing shores. A storm force low developing near Kamchatka over the next few days will generate some longer period energy out of the northwest around September 2nd. This swell could generate surf near the September average during its peak. For the month of September the average surf heights along north facing shores is 4 to 6 feet (Goddard-Caldwell Database). Small short-period surf along east facing shores will decrease on Thursday as winds locally and upstream ease through the weekend into early next week. && .FIRE WEATHER... Low relative humidity values and hot conditions will continue through the first half of next week due to the arrival of a drier airmass. However, low wind speeds will keep us from reaching critical fire weather thresholds. By midweek next week, the broad high pressure ridge will rebuild, and may result in winds strengthening a bit, though still does not appear to reach critical thresholds at this time. Temperature inversion heights near Maui and the Big Island will range from around 6,000 to 7,000 feet today. && .HFO WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Pierce AVIATION...Pierce MARINE...Bohlin FIRE WEATHER...Pierce