textproduct: Honolulu

SYNOPSIS

Trades will continue through early next week with subtle fluctuations in speed. Showers may favor some leeward and interior areas tomorrow afternoon in the lighter, slightly veered flow. Otherwise, batches of moisture will filter in on the trade wind flow, bringing periodic upticks in windward and mauka shower activity, particularly during the overnight to early morning periods.

DISCUSSION

Radar and satellite imagery show that shower coverage has gradually decreased this afternoon, with remaining activity continuing to favor the western half of the state. Upstream moisture suggests a slight uptick in shower coverage across windward and mauka areas statewide overnight.

High pressure far north of the area will be gradually nudged eastward through the weekend as a series of lows pass through the far northeast Pacific. Another high will then build in behind it from the northwest early next week. The progression of these features, along with two areas of potential tropical development to the south and southwest of the state, will bring subtle ebbs and flows in the local pressure gradient, consequently altering trade wind speeds through the period. Wind speeds will be moderate to locally breezy over the next couple of days, strengthen to become breezy through the weekend, and then potentially weaken slightly once again early next week. The two areas south and southwest of the state being watched for potential tropical cyclone development are not expected to have any direct impacts on Hawaii at this time.

Batches of moisture will filter in on the trades, bringing periodic upticks in windward and mauka showers through the period. While most shower activity will remain focused over windward and mauka areas during the overnight to early morning hours, short- term guidance suggests that the low-level flow will temporarily veer slightly south of east tomorrow. This will increase the potential for isolated sea breeze showers over leeward areas across the state, and may allow convergent boundaries downwind of Molokai to bring showers to leeward Oahu tomorrow afternoon.

AVIATION

Trades will weaken to moderate speeds and veer out of a more easterly direction through tonight. Mainly scattered showers with brief periods of MVFR conditions are expected through Wednesday. Showers will primarily impact windward areas, with some spillover into leeward areas possible. Otherwise, VFR will prevail.

MARINE

No significant changes to the forecast with the afternoon package. The Coastal Flood statement remains posted for higher than normal tides since we are in the midsts of the afternoon peak tides. Anticipate cancelling that statement by 6 pm today as the high tides begins to subside.

High pressure far north of the islands will maintain a trade wind pattern, however as the high has weakened and lifted away from the islands, trade winds are not quite as strong. Winds across the coastal waters remain below Small Craft Advisory levels. Winds could rebound during the second half of the week as the high sinks southward, tightening the pressure gradient over the islands.

The current small, long-period southwest swell will continue to gradually decline through the middle of the week. A series of overlapping small south and southwest swells will maintain south shore surf, with a larger south swell expected early next week.

Surf along east-facing shores will steadily decline through Wednesday as the trade winds ease. Surf will then hold steady at slightly below seasonal averages along east facing shores through the weekend.

A series of small, long to medium period west to west-northwest swells generated by former Super Typhoon Bavi will be possible throughout the rest of the week. Otherwise, no significant north or northwest swells are expected.

Coastal flooding remains possible this afternoon with the peak monthly high tides, combined with water levels running slightly higher than predicted. The Coastal Flood Statement will be cancelled later this afternoon after the peak of the high tide.

HFO WATCHES/WARNINGS/ADVISORIES

None.