15-25++ foot
8-12++ foot
0-3 foot
8-12++ foot

Long period swell energy has arrived at Buoy 51101 during the past several hours, and the swell height is now rising quickly there, with the buoy reporting 16 feet at 21 seconds as of 3 AM. This is only a few hours behind the timing indicated by the latest Wavewatch guidance. Satellite altimetry passes during Friday evening also showed the significant wave heights remaining on target with Wavewatch guidance. Therefore no significant changes are anticipated from earlier thinking with the incoming northwest swell event.

The High Surf Warning remains in place for the north and west facing shores of Niihau, Kauai, Oahu, and Molokai; and north facing shores of Maui and the Big Island. A High Surf Warning for the west facing shores of the Big Island will go into effect this morning. The extra-large northwest swell will build rapidly, bringing surf heights well above warning levels to exposed shores on the smaller islands by this morning, and to the Big Island areas in the afternoon. Warning level surf should be expected to continue through the weekend and possibly into Monday. As the swell subsides, surf should remain at advisory levels into mid- week before another northwest swell arrives Wednesday night.

A Small Craft Advisory is in effect for all Hawaiian coastal waters, except Maalaea Bay, due to seas. Seas will rapidly ramp up to near 20 ft and above as the new swell arrives. A ridge over the state will keep winds light through the weekend. The ridge will move north late Sunday, with moderate to locally breezy trade winds returning at the beginning of the work week. Winds will then increase through the new week.

Extra-large swells, like the one arriving this morning, have the potential to cause significant impacts to shorelines, especially ones already prone to erosion. This type of event usually generates well above coastal overwash, especially when coinciding with high tides. The highest tide has already occurred this morning, but throughout the state it will occur again between 130 and 300 AM HST Sunday morning, with values between 1.6 and 2.6 ft. Additionally, harbors with northern/northwestern exposures could see impacts from potential surging.

Hawaii Wave Height Model

Tide Predictions

A single tide at Kahului will be foot at

tide at Kahului was foot at just after midnight, of foot at just after midnight, then of foot at just after midnight, before once again of foot at just after midnight

The sunrise was at 07:03 am this morning and will set at 06:06 pm this evening. The Moon is currently 27 days old, and is in a Waning Crescent phase. The next New Moon will occur at 2:18 AM on Wednesday, January 17th.

Hawaii Wind Report

Maui Weather

72°/74°
Wind: NE at 16 mph
Sunrise: 6:03 AM
Sunset: 6:46 PM
current observations as of 4am April 20th, 2018

Weather Outlook for Saturday, 13th January 2018

Summary

Light winds and mainly dry conditions will prevail through the weekend, with mostly clear nights and mornings, and partly cloudy afternoons bringing a slight chance of a brief shower. Trade winds will return and strengthen through the first half of next week, likely becoming quite strong by midweek. Windward and mauka showers will gradually become more frequent as the trade winds increase.

Detailed Discussion

Quiet and dry weather prevails across the state on this early Saturday morning. Radar and rain gauges have shown zero shower activity over the islands during the last several hours. Surface analysis shows the area in a very weak pressure pattern, between high pressure ridges to the WNW and ENE, and a huge area of low pressure which currently dominates the North Pacific. The resulting light background wind flow is allowing a nighttime land breeze and daytime sea breeze regime to prevail over the islands. Water vapor imagery shows a deep layered ridge building over the state from the west, with a weakening upper level trough being pushed well south and east of the Big Island. MIMIC-TPW imagery depicts the drier airmass which has been present over the western islands now spreading over the Big Island as well. The 12Z Hilo sounding showed a strengthening inversion near 10K feet, with PW of 1.37 inches, while the 12Z Lihue sounding reflects a very stable and dry profile with PW of only 0.92 inches and an exceptionally low inversion based at 2000 feet.

The surface ridge will remain over the state today and tonight, then drift slowly northward Sunday through Monday. A light northerly background wind flow is expected today, veering around to the typical ENE trade wind direction on Sunday. Winds are expected to remain light enough through Sunday to allow land/sea breeze development to continue. Trade winds are forecast to become more defined Sunday night and Monday, with sea breezes on Monday afternoon becoming confined to sheltered regions such as the Kona coast of the Big Island and the Barking Sands area on Kauai. Rain chances will remain low to nil throughout this period, especially over the western and central islands, as models are in good agreement in showing the deep layered ridge continuing to build eastward over the state. This will severely limit rainfall potential statewide, with even the Big Island expected to see less shower activity today than was observed on Friday afternoon. The weekend weather will be dominated by mostly clear nights and mornings, with some interior and upslope afternoon cloudiness producing very limited rainfall, if any.

A much stronger surface high is forecast to build far to our north by the middle of next week, in the wake of a weak front. The front will not have any direct impact on our weather, but the building high will cause trade winds to ramp up considerably by Wednesday, with latest guidance continuing the earlier theme of 25-35 mph winds over the open ocean. Winds this strong interacting with island terrain in a stable environment will likely necessitate a Wind Advisory, but there is still plenty of time for forecast guidance to change. The most recent ECMWF model run shows trade winds decreasing somewhat by Friday as a weak surface trough develops well to the west of the state, but the last couple of GFS runs keep the strong trades going right through the end of next week and into next weekend.

The strengthening trades would normally be expected to bring increased showers to windward portions of the islands, but the deep ridging aloft is forecast to hold strong through much of next week, keeping the showers limited in strength and coverage. A weak upper trough developing to our west may allow for somewhat higher rain chances by the later part of next week.

Central Valley (Kahului, Spreckelsville):

HIGH SURF WARNING IN EFFECT UNTIL 6 PM HST SUNDAY. Sunny. Highs 79 to 84. North winds up to 10 mph increasing to 10 to 15 mph in the afternoon.

Leeward West (Lahaina, Ka`anapali):

Mostly clear. Isolated showers after midnight. Lows 59 to 66. Northeast winds up to 10 mph early in the evening becoming light. Chance of rain 20 percent.

Windward West (Wailuku, Waiehu):

HIGH SURF WARNING IN EFFECT UNTIL 6 PM HST SUNDAY. Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 62 to 81. North winds up to 10 mph. Chance of rain 20 percent.

Windard Haleakala (Hana, Haiku, Makawao):

HIGH SURF WARNING IN EFFECT UNTIL 6 PM HST SUNDAY. Mostly sunny. Isolated showers in the afternoon. Highs around 79 at the shore to around 65 at 5000 feet. North winds up to 10 mph. Chance of rain 20 percent.

Leeward Haleakala (Kihei, Wailea, Makena):

Mostly clear. Lows around 62 at the shore to 46 to 51 upcountry. Light winds.

Haleakala Summit

Mostly clear. Lows around 45 at the visitor center to around 42 at the summit. Light winds becoming northeast around 10 mph early in the morning.

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