A high pressure system far northwest of the Hawaiian Islands will slowly drift from west to east over the next few days. This passing system will increase easterly trade winds into the moderate to breezy range lasting into the middle of next week. Brief pulses of enhanced showers are forecast with three passing easterly waves during this time period. Increasing shower trends will favor the windward mountain areas in the overnight to early morning hours starting Friday night and lingering into Tuesday morning. The strongest of these three waves will pass through the islands from Sunday night into Tuesday morning.
Trade winds will become more gusty today and isolated showers across windward areas of the Big Island could create isolated MVFR condition and possibly into Maui. Otherwise VFR conditions will prevail over the rest of the terminals.
No AIRMETs are in effect, however as winds increase, AIRMET Tango may be needed for mechanical turbulence to the lee of the mountains.
Surface high pressure far northwest of the islands will move closer today, then build as it shifts north and then northeast of Hawaii on Friday. As a result, trade winds will gradually increase to fresh to locally strong levels over the next couple of days. A Small Craft Advisory (SCA) is in effect for the typically windy waters around Big Island and Maui beginning at 6 am this morning. A stronger surface high will arrive far north of the islands late Saturday and Sunday, likely increasing trade winds further, which may necessitate an expansion of the SCA to additional waters. Elevated trade winds will persist into early next week.
The current small bump in the northwest swell will fade tonight before a moderate north-northwest swell arrives Friday and continues through the weekend. Surf along north and west-facing shores should top out around seasonal average or slightly higher during the peak of the swell Friday afternoon and Saturday, then slowly decline late Saturday and Sunday as the dropping swell shifts more northerly and a smaller overlapping northwest swell arrives. Both swells will fade early next week.
A new long-periond south swell builds today and may push surf along south-facing shores back above seasonal average into Friday. The swell will slowly decline Saturday through early next week.
Surf along east-facing shores will begin to increase this afternoon into tonight as trade winds strengthen over the region. Expect some wrap from the moderate north-northwest swell tomorrow afternoon into Saturday. Rough trade wind swell will produce east shore surf above seasonal average Saturday through early next week.
Small Craft Advisory until 6 PM HST Saturday for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Maalaea Bay-Pailolo Channel.
