Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
118 FXHW60 PHFO 240115 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 315 PM HST Sat Aug 23 2025 .SYNOPSIS... The locally breezy trade wind flow will ease slightly on Sunday and Monday as surface high pressure to the north weakens. Stable conditions will continue to produce minimal windward rainfall, and with the exception of scattered afternoon and evening showers over the Kona slopes of the Big Island, leeward areas will be mostly dry. Moderate trade winds and the typically dry summertime weather pattern will prevail for the remainder of next week. && .DISCUSSION... The rather dry summertime trade wind weather pattern continues. Broad surface high pressure far north of the islands is beginning to be split by a North Pacific trough, but so far, locally breezy trade winds are only down a few miles per hour compared to yesterday. Precipitable water in the trade flow is running around 1.1 inches, which is about 20 to 25 percent below August normal, and a robust mid-level ridge is maintaining a strong inversion based between 5,000 and 7,000 ft. Under these stable and rather dry conditions, rainfall has been scant across windward areas, and aside from a few showers developing along the Kona slopes of the Big Island, leeward areas continue to be dry. Only minor changes are expected during the next few days. Trades will ease slightly and shift from a more easterly direction Sunday and Monday. As a result, afternoon sea breezes will be more prevalent, but most areas will not experience any increase in shower chances, even as the inversion rises a bit. However, the GFS and ECMWF models are showing a minor increase in moisture near the Big Island Monday and Tuesday that may provide some increase in afternoon showers on the Kona slopes. Moderate trade winds and stable conditions with modest rainfall will prevail from Wednesday into next next weekend. && .AVIATION... Stable, moderate to breezy trades deliver clouds and showers windward and mauka through the period particularly overnight and during the early morning hours. Isolated MVFR within showers otherwise VFR prevails. No AIRMETs in effect. && .MARINE... A ridge of high pressure north of the Hawaiian Islands will continue to produce fresh to locally strong trades through early next week. A Small Craft Advisory (SCA) remains in effect for the windier waters of Maui County and the Big Island. This SCA may continue into the first half of next week. Small overlapping medium and long period south swells will continue this afternoon and slowly fade into background levels by Sunday. Surf heights will continue to decline into Monday. Another series of small long period south swells will arrive by Tuesday, boosting south shore surf heights through Friday. Surf along north and west facing shores will remain nearly flat for the next few days, while small trade wind driven wave chop will linger for east shores. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST Sunday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...Wroe AVIATION...JVC MARINE...Tsamous