Trade winds are expected to persistently blow through the Hawaiian Islands, as reported by NWS - Honolulu Weather Forecast. The NWS forecast suggests that these winds, which are caused by a high-pressure system far north of the region, should continue through the upcoming weekend. Accompanying these breezy conditions are passing showers that will mostly affect windward areas, with the possibility of some spreading to leeward locations, particularly at night and in the morning.
A slow-moving trough is to likely bring some mid-level cooling as it moves southward over the next couple of days, weakening the subsidence inversion. What this means is that there will be an increase in shower activity, driven by orographic lift and random clusters arriving on the trade winds. The situation is expected to result in occasional showers across windward areas and possibly extending to leeward regions, with these showers being most active overnight and during early hours.
In terms of aviation, moderate to locally breezy trade winds are set to deliver low clouds and showers to windward and mauka spots throughout the forecast period. The NWS states, "Brief MVFR conds can be expected within SHRA but VFR should generally prevail." Pilots should expect mountain obscuration in windward locations, but these conditions are anticipated to improve by mid-morning.
For mariners, the area of high pressure north of Hawaii is creating moderate to strong trade winds across the local waters. The National Weather Service has issued a Small Craft Advisory, which has been extended until Thursday morning for various channels and waters, particularly around Maui County and the Big Island. This advisory is likely to be extended later into the week. As for surf conditions, south facing shores will experience increased surf due to a long-period southerly swell that is projected to arrive and peak on Wednesday.
All these weather phenomena are easily comprehended within the everyday dynamics of what makes the islands a place of both predictable trade winds and capricious showers. As for precautions, mariners should be aware of the extended Small Craft Advisory and take necessary measures when planning their activities at sea. Meanwhile, beachgoers can look forward to the upcoming swell, which should heighten the surf above the usual August averages.
