Honolulu residents can expect a continuation of trade winds for the coming week with a slow decline before picking back up later in the weekend, as noted by the National Weather Service - Honolulu. The weather dynamics include two upper-level lows causing some instability, leading to isolated thunderstorms, primarily in western areas up until Wednesday. The National Weather Service report details a low drifting northwest with tropical moisture causing isolated showers across Hawaii, although the thunderstorms should remain over the ocean and are very isolated at that.
A weakening upper-level low will turn into a trough tonight and linger through Tuesday, bringing cooler air that could cause a few isolated thunderstorms. The usual trade winds will continue as the system moves east, but another low is expected to form far southwest of the islands by late Wednesday and drift west for a few days. Looking ahead, another weather system could affect the islands next weekend, though forecasts still differ on the details. Trade winds are easing, so the Small Craft Advisory has been reduced to just the windiest areas and should end completely by Monday morning, as reported by the National Weather Service.
Aviation updates from the National Weather Service report a gradual decrease in trade winds through the week with isolated to scattered showers bringing potential low clouds and marginal visual flight rules (MVFR) conditions; Mountain obscuration from Kauai to the Big Island is ongoing, but conditions should improve in the coming morning hours. Mariners should note the north-northwest swell tapering off today, with a small to moderate north-northwest swell anticipated to push surf along north and west-facing shores to near seasonal averages by Monday, then declining on Tuesday.
Additionally, east-facing shores will see rough surf subsiding midweek as the trade winds calm, the north swell hitting midweek could affect surf on some eastern exposures and with the anticipated lower trade winds; the overall conditions should become more placid across the state's coastlines. Conversely, south-facing shores are expected to only receive small background swells throughout the week. The National Weather Service report highlights a decrease in critical fire weather conditions with higher humidity and diminishing winds keeping fire threats below critical thresholds. Temperatures at the inversion layers will hover around 8,000 to 9,000 feet, benefiting firefighting efforts by keeping the air relatively stable.
For the interim, the National Weather Service has issued a Small Craft Advisory until 6 PM HST this evening for select waters, as well as an extension through to 6 AM HST Monday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, and certain areas around the Big Island, signaling that mariners should exercise caution due to the stronger trade winds and sea conditions expected during this time.
