Marine Weather and Tide Forecast for Princeville, HI

DISCUSSION
This evening, broad high pressure north and northeast of the islands is producing fresh to locally strong trade winds across the state. Observations from earlier in the day showed that sustained trade wind speeds reached close to or exceeded 25 kts across portions of the state during the afternoon, particularly across Maui and the Big Island. Additionally, a wind advisory remains in effect for the Big Island summits tonight, where sustained winds have consistently reached between 45-55 mph since early afternoon. These locally strong trades are expected to continue into Wednesday, potentially flirting with advisory criteria again at the summits and at some of the windier lower elevation locations as well. Observations from earlier today also showed that we neared Red Flag Warning criteria at Honolulu, which is possible again Wednesday afternoon. See the Fire Weather section below for more details.

An advancing cold front well north of Hawaii will displace the driving high pressure further northeast of the islands, slightly weakening wind speeds Thursday night. Meanwhile, a nearly stationary low pressure system will set up northwest of Hawaii.
The pressure gradient between these two features will continue to maintain moderate and slightly veered east southeasterly winds into Friday. Island terrain blockage under this wind regime will further weaken the winds across leeward areas, resulting in localized sea breezes and interior clouds Friday afternoon before the trade winds strengthen back this weekend.

Trades will carry in brief clouds and showers over the islands through Wednesday, focusing mainly over windward and mauka areas.
A mid-level trough will move over windward and southeast Big Island Wednesday night, then spread westward during the second half of the week. This feature will bring an increase in clouds and showers through Friday night. A weak upper level low moving into position northeast of the state during this time may also enhance the incoming showers. The forecast will trend drier with a continuation of the moderate east southeast flow from Saturday into the middle of next week.

AVIATION
Breezy easterly trade winds will prevail during the next 24 hours, with limited low clouds and showers focusing mainly over windward and mountain areas. Predominantly VFR conditions are expected.

AIRMET Tango remains in effect for moderate low-level turbulence over and downwind of the island terrain. This AIRMET will likely be needed through Wednesday.

MARINE
The high pressure ridge north of the island will build tonight, producing fresh to strong trade winds through Wednesday with the strongest winds reaching near gale conditions in the windiest eastern channels. The Small Craft Advisory (SCA) remains in effect for all waters tonight due to winds mainly over the central and eastern waters and elevated seas across the waters north and west of Oahu. This SCA will decrease in coverage, with most of the western waters dropping out, as seas gradually subside tonight.
However, this SCA will remain in effect for central and eastern waters as strong trade winds persist. Trade wind speeds will fall below SCA conditions by Thursday night as the ridge weakens north of the island chain.

The current north (350) medium period swell will continue to slowly subside tonight. NDBC buoys 51001, 51101, and 51000 continue to show gradual decreasing trends tonight still remaining about 1 foot higher than the model guidance. The High Surf Advisory remains in effect through Wednesday morning to capture the trailing end of the high surf period as this north swell slowly falls below advisory thresholds.

Surf along west facing shores remains slightly elevated with wrap around north swell energy lingering for the next few days. Surf along east shores will remain elevated through Wednesday in response to short period trade wind swell over and upstream of the islands. Surf then declines in concert with weakening trades during the latter half of the week. However, east facing shores exposed to the north swell will continue to see some wrap during the next couple days. South shore surf will remain small mainly due to south and southeast background swells into next week. The next small long period south swell pulse will arrive in Hawaii from Friday into Saturday.

FIRE WEATHER
A combination of gusty winds, relatively stable and dry conditions, and dry fuels (with Keetch-Byram Drought Index (KBDI)
values well over 600) could present some fire weather concerns on Wednesday. Relative humidity values dropped to near 45% during the afternoon on Tuesday, and with Wednesday expected to be similar or slightly drier, it is possible that red flag criteria could be met from late morning into the afternoon when RH is at a minimum and wind speeds are maximized.

HFO WATCHES/WARNINGS/ADVISORIES
High Surf Advisory until 6 AM HST Wednesday for north facing shores of Kauai, Oahu, Molokai, Maui, and the Big Island.

Wind Advisory until 6 AM HST Wednesday for Big Island Summits.

Small Craft Advisory until 6 AM HST Wednesday for Kauai Northwest Waters-Kauai Windward Waters-Kauai Leeward Waters- Kauai Channel-Oahu Windward Waters.

Small Craft Advisory until 6 PM HST Wednesday for Oahu Leeward Waters-Kaiwi Channel-Maui County Windward Waters-Maui County Leeward Waters-Maalaea Bay-Pailolo Channel-Alenuihaha Channel- Big Island Windward Waters-Big Island Leeward Waters-Big Island Southeast Waters.