Marine Weather and Tide Forecast for Haleiwa, HI

DISCUSSION
The satellite picture this morning shows a narrow upper level trough extending from west to east across the Central Pacific basin. A weak upper low remains anchored directly over Hawaii, bringing a flavor of instability to the cloud bands riding into each island on the trade winds that will last through Sunday.
Farther to the north, the subtropical ridge remains anchored in place for the next seven days, keeping moderate to locally breezy trade winds in the forecast through much of next week. A band of unstable clouds is currently moving into the islands from the east, producing wet roads this morning for some island commuters.

The island weather pattern will remain in a fairly unsettled trade wind regime into the first half of next week, mainly due to the proximity of the upper level low pressure system keeping temperature inversion heights in the 8,000 to 10,000 foot range.
At this level cloud heights grow tall enough as they are lifted over island mountains to produce periods of rainfall, especially during the diurnal rainfall maximum from the overnight to early morning hours. A brief period of thunderstorms are possible on Saturday afternoon along the western slopes of the Big Island, as deeper moisture at 700 mb is lifted by strong surface heating along the slopes of Mauna Loa.

Our forecast guidance into next week shows a very similar weather pattern with the ridge locked in north of the state and a weak upper low lurking over the Hawaiian Islands. Only subtle changes in the island by island weather pattern should be expected over the next seven days.

AVIATION
Moderate to breezy trade winds continue across the island chain into Saturday, steered by high pressure centered far northeast of the main Hawaiian Islands. Low clouds and passing showers embedded within the trades will favor north through east sections of most islands throughout the period, especially during the overnight to early morning hours. While VFR flight conditions will prevail at most locations, periods of MVFR conditions will be possible within any showers especially over windward airfields.

AIRMET SIERRA remains in effect for mountain obscurations along windward sections of Oahu, Molokai, Maui and the Big Island. These conditions will continue through the morning hours.

AIRMET Tango remains in effect for low level moderate turbulence over and immediately S through W of all islands mountains. AIRMET Tango also remains in effect for upper level moderate turbulence from Molokai eastward to the Big Island. Low level turbulence impacts will continue into the weekend.

MARINE
Strong high pressure will remain anchored northeast of the state today and tonight, keeping fresh to strong trades in place. A developing trough to the distant northwest is expected to ease the trades over the weekend into early next week. Light to moderate trades with localized sea breezes are expected over the western islands, while moderate to locally strong persist over the eastern end of the state.

A Small Craft Advisory (SCA) is now in effect for most marine zones east of Oahu through 6 am Saturday, and for some of the windier zones around Maui and the Big Island through 6 pm Saturday. The SCA may need to be extended for the typically windy waters over the eastern end of the state through the weekend.

Surf along north and west-facing shores will remain very small during the next 7 days. Surf along south-facing shores will hold at background levels today and tonight. A series of small south and south-southwest swells will give a small boost to south shore surf over the weekend, with a further boost up to the seasonal average possible during the middle to latter part of next week.

Surf along east-facing shores will hold close to normal levels during the next 7 days.

HFO WATCHES/WARNINGS/ADVISORIES
Small Craft Advisory until 6 PM HST Friday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Windward Waters- Big Island Leeward Waters-Big Island Southeast Waters.