A ridge to the north of the islands will weaken slightly the rest of the week, allowing trade winds to diminish briefly to moderate levels tonight into Friday before gradually restrengthening back to locally breezy levels over the weekend. Clouds and showers will remain focused mainly along windward and mauka areas into early next week. A drier airmass moving in from the east is expected to limit shower activity into the weekend.
The grids were updated with the morning package to bring it in line with the latest NBM, but little change to the forecast.
High pressure far to the north of the islands will remain into the weekend. Winds are expected to weaken a bit tonight and tomorrow to moderate levels, but then strengthen a bit this weekend to moderate to locally breezy levels.
Satellite derived precipitable water shows a drier airmass moving into the islands today, and that will limit shower activity. Any clouds and showers that do get carried in on the trade wind flow will be focused over the windward and mauka areas. No significant rainfall totals are expected over the next couple of days.
Dewpoints have been in the low 70s the last couple of days, but have started to slowly lower back into the upper 60s, which will make it a little less muggy. Expect dewpoints to remain in the mid to upper 60s through the holiday weekend.
Tropical Storm Douglas in the east Pacific is expected to weaken to a remnant low Friday. Remnant moisture from this system will likely be carried into the islands on the trade wind flow during the middle to latter half of the new week. This could increase shower activity, mainly to the windward and mauka locations.
Moderate to locally breezy trades will continue through the holiday weekend, focusing low clouds and limited showers over windward and mountain areas. MVFR conditions are possible in showers, otherwise, VFR conditions are expected to prevail.
AIRMET Sierra is in effect for mountain obscuration for windward areas of the Big Island due to ongoing showers. Looking upstream of the Big Island, there may be a break in shower activity as some drier air filters in later this morning.
AIRMET Tango is currently in effect for moderate turbulence downwind of terrain due to breezy trade winds.
Surface high pressure far north of the islands will maintain moderate to locally strong trade winds today before slightly declining, becoming moderate to fresh through the rest of the forecast period. A Small Craft Advisory (SCA) is in effect through 6 PM this evening for the typical windy waters and channels around Maui County and the Big Island.
A small, medium-period south swell will linger today just below the summertime average. This fading swell combined with a series of small, medium- to long-period south- southwesterly swells, will deliver below-average surf along south-facing shores through Friday. Over the holiday weekend and into early next week, a moderate, long-period south-southwest swell will arrive, boosting surf heights to near High Surf Advisory levels Sunday into Monday.
Surf along east facing shores will remain rough and choppy through Friday as trade winds remain locally strong. Surf along north facing shores will remain tiny through the forecast period, with a minor uptick possible Friday into the holiday weekend as a small, medium- period northwest swell arrives.
Small Craft Advisory until 6 PM HST this evening for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Maalaea Bay-Pailolo Channel.
