Strong trade winds are expected today as high pressure continues to build south toward the state. Windward and mauka showers increase today as decaying frontal boundary moves from north to south across the state. Moderate to locally breezy trades will return Friday.
A weakening frontal boundary will bring some deeper moisture south through the islands today. Increased shower coverage is expected over mostly windward and mauka areas, but a few may make it into leeward areas too. The Wind Advisory has been cancelled but winds could still be strong and gusty today but look to remain below advisory thresholds.
The strong trade winds should ease some Friday down to breezy to locally strong speeds. Another high pressure ridge will slide east well to the north of the state this weekend. Some increase in the trades is possible again Saturday night and Sunday before the high stalls to our northeast early next week. A reduced pressure gradient should allow trades to relax some by that time. Brief pulses of better moisture in the trades will keep typical trade wind showers over windward and mauka areas mostly during the overnight and early morning hours through the period.
Locally strong trade winds will continue today before gradually weakening through the second half of the week. A dying frontal boundary is making its way through the island chain this morning, providing an increase in shower activity. Windward and mountain areas will see most of the showers, but leeward areas could see some spillover showers as well. MVFR conditions are expected within showers while VFR prevails elsewhere. Showers will quickly decrease later this morning across Kauai and Oahu, and linger around Maui County and the Big Island a bit longer during the afternoon.
AIRMET Tango is in effect for low level moderate turbulence downwind of terrain, and for strong surface winds 30 kt or greater over Maui County and the Big Island. Expect the strong surface winds to weaken later this morning. AIRMET Tango will likely remain in effect for low level moderate turbulence through the next several days.
AIRMET Sierra is in effect for mountain obscurations across windward sections of the smaller islands as the frontal boundary moves down the island chain this morning.
Strong high pressure north of Hawaii will maintain fresh to near gale force winds across the marine areas through tonight. The Gale Warning has been discontinued in favor of a Small Craft Advisory (SCA) which covers all coastal waters. The SCA has been extended through tonight, with a gradual tapering of winds forecast and some uncertainty on how widespread strong trades will be by Friday. Seas are also in excess of 10 feet with a large north-northwest swell moving through the area. A weakening front will drop south across central waters today as it weakens to a trough. This disturbance will bring increased shower activity to the area until it dissipates tonight. Though trade winds diminish some for Friday and Saturday, high pressure restrengthening northeast of the islands may bring more widespread strong winds Sunday and Monday to all waters.
PacIOOS Buoy 51201 near Waimea Bay observed the peak of the large, north-northwest swell late last evening at nearly 11 feet with a 15 second period. A High Surf Advisory (HSA) remains in effect for north- facing shores of Kauai, Oahu, Molokai and Maui and west- facing shores of Kauai and Oahu through this afternoon. The large swell will generally maintain through the morning before declining this afternoon and falling below advisory criteria tonight. Surf will continue to decrease Friday, but will see a small bump on Saturday with a new north-northwest swell, followed by a more significant north swell which could push surf back to advisory levels on Sunday.
Surf along east-facing shores will remain rough and choppy due to the strong trade winds through Friday, then may diminish slightly this weekend. A small, long-period south swell may bring a small bump to south shore surf today. Surf becomes tiny again Friday into the weekend for south-facing shores.
High Surf Advisory until 6 PM HST this evening for Niihau- Waianae Coast-Oahu North Shore-Maui Windward West-Kauai North- Molokai Windward-Molokai North-Molokai West-Maui Central Valley North-Windward Haleakala.
Small Craft Advisory until 6 AM HST Friday for all Hawaiian waters-
