Hilo

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Kona

:

Waimea

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Kohala

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South Big Island

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Puna

:

Waikoloa

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Detailed Forecast

Synopsis

Moderate to locally breezy trade winds will prevail through Sunday, then ease through the first half of next week. Showers will favor windward and mauka areas with a few showers spilling leeward during this time. The trades will cut off late Wednesday through Thursday as a front approaches from the north, with showers favoring the island interiors each afternoon. A cold front could bring some more widespread rainfall to the island chain Thursday night and Friday, with the potential for some heavier showers and even a few thunderstorms not out of the question. A transition back to a more typical trade wind pattern is expected for next weekend.

Discussion

Currently at the surface, a ridge of high pressure is positioned around 400 miles north of Kauai, while a cold front is located around 1300 miles west-northwest of the Garden Isle. Moderate to breezy trade winds prevail across the island chain this evening. Infrared satellite imagery shows mostly cloudy conditions in windward areas and clear to partly cloudy skies in most leeward locales. Radar imagery shows scattered trade wind showers moving into windward slopes and coasts with some of these showers reaching leeward areas at times. Main short term
The ridge of high pressure north of the islands will keep moderate to locally breezy trade winds in place through Sunday. The trades will ease slightly on Monday as an approaching front weakens the ridge north of the state. The trades will briefly rebound back to moderate levels Tuesday as a new high builds north-northwest of the islands and trough of low pressure sets up to the northeast. The trades will begin easing again Wednesday as a new front begins to approach from the northwest. Light and variable winds will develop Wednesday night and continue into Thursday ahead of the front, with moderate to locally breezy northeasterly trades filling in from northwest to southeast down the island chain Thursday night and Friday behind the front. A new high building northwest of the state will then keep moderate to locally breezy northeasterly trades into next weekend.
As for the remaining weather details, a fairly typical winter time trade wind pattern will prevail through Wednesday, with showers favoring windward slopes and coasts. Showers will be most prevalent during the overnight and early morning hours, with a few showers reaching leeward areas from time to time. As the trades cut off Wednesday afternoon through Thursday, showers will decrease in coverage and favor the island interiors each afternoon and the coastal waters at night. Depending on the strength and progression of a cold front into/through the islands Thursday night and Friday, we could see more widespread rain affect the islands, with some heavier showers and even some thunderstorms not out of the question. In the wake of the front, we will transition back into a trade wind regime next weekend.

Aviation

Moderate to locally breezy trades will bring scattered showers to mainly windward locations tonight. However, some isolated spillover showers will reach leeward sides. Weak instability from an upper-level low lingering south of the Big Island could aid in the development of some heavier showers along windward portions of the Big Island through Sunday morning.
AIRMET Tango remains in effect for low-level mechanical turbulence associated with the breezy trade winds.

Marine

Surface high pressure far northeast of the state will drive moderate to locally strong trades through the rest of the weekend before easing slightly through the early half of next week as the ridge to the north weakens as a front passes by to the north. The trades are expected to become disrupted entirely by Thursday with light winds over the marine area as a potential cold front moves through the area. A Small Craft Advisory (SCA) is currently in effect for the windier waters and channels around Maui and the Big island through 6 pm HST Sunday.
A new moderate long-period northwest swell will build in late tonight, peak Sunday into Sunday night, then lower on Monday. Long period 19 second forerunners have begun showing up on the offshore NDBC buoy 51101 around 4 pm HST this afternoon. This swell will give a slight boost to surf along north and west facing shores Sunday, but will likely remain below advisory levels.
A slightly larger northwest swell will arrive early Monday, peak Monday through Tuesday, then gradually decline through Thursday. This swell may bring surf heights up to High Surf Advisory (HSA) criteria for most north and west facing shores Monday through Tuesday night. Then, an even larger, long-period northwest swell is expected fill in for the end of next week that could bring High Surf Warning (HSW) level surf to most north and west facing shores next Friday.
East shore surf will hold relatively steady through Sunday, then lower a bit Monday and Tuesday as the trades ease. East shore surf looks to become very small Wednesday and Thursday as the trades become disrupted, with a north swell potentially giving surf a boost to exposed shorelines next Friday.
South shore surf will remain very small through the middle of next week. An out of season long-period south swell may move through the islands late next week, bringing a sizable boost to south shore surf.

Fire weather

No critical fire conditions anticipated during the forecast period.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov