textproduct: Honolulu

SYNOPSIS

A ridge to the north of the islands will weaken slightly through the latter half of the week, allowing trade winds to diminish briefly to moderate levels Thursday night into Friday before gradually restrengthening back to locally breezy 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.

DISCUSSION

High pressure remains far north-northeast of the islands today with an associated ridge near 40N. This will produce moderate easterly trade winds which should be locally breezy through Thursday before a slight weakening of the ridge induces a slight reduction in trades Thursday night into Friday. Then, the high is expected to sink southward slowly this weekend, which will allow trade winds to gradually restrengthen.

A drier airmass moving into the islands, as indicated in satellite derived precipitable water, will linger into the weekend. Expect a return to drier conditions, with dew points already beginning to drop below 70 degrees at some locations this afternoon, and less coverage of rain showers. Otherwise, the typical trade wind showers will focus along the windward and mauka areas, which will be most widespread at night and in the early morning hours.

Looking into next week, the remnant low of Tropical Storm Douglas in the Eastern Pacific is forecast to track to the northeast of the islands. At this point, impacts appear limited, with an increase of rain showers possible some time mid to late next week with trailing moisture.

AVIATION

Moderate to locally breezy trades will continue through the holiday weekend. Showers will be limited over the next couple of days, but are still possible primarily over windward and mountain areas. Expect MVFR conditions in showers, and VFR elsewhere.

AIRMET Sierra is in effect for mountain obscurations for windward areas of Maui due to ongoing and upstream showers. Other windward areas may have mountain obscurations later tonight due to overnight showers, with windward Big Island being the most likely.

AIRMET Tango is currently in effect for moderate turbulence downwind of terrain due to breezy trade winds.

MARINE

Surface high pressure far north of the islands will maintain moderate to locally strong trade winds through Thursday before declining slightly to become moderate to fresh through the rest of the forecast period. The Small Craft Advisory (SCA) is in effect through Thursday afternoon for the windier waters and channels around Maui County and the Big Island.

A small, medium-period south swell will linger through Thursday 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 potentially Sunday into Monday.

Surf along east facing shores will remain rough and choppy through Thursday as trade winds remain locally strong. Surf along north facing shores will remain flat to tiny through the forecast period, with a minor uptick possible Friday into the holiday weekend as a small, medium-period northwest swell arrives.

HFO WATCHES/WARNINGS/ADVISORIES

Small Craft Advisory until 6 PM HST Thursday for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Maalaea Bay-Pailolo Channel.