5-8+ foot
3-5 foot
0-2 foot
2-4 foot

Trades are forecast to hold in the fresh to strong category through the weekend as high pressure builds north of the state in the wake of a dissipating front pushing south across the islands. Overnight satellite data showed this frontal boundary extending west-southwest across the Oahu and Kauai waters with wind speeds up to 25 knots surrounding it. Trades may reach the strong category across most waters Tuesday through Wednesday with near gales possible across the typically windier waters between Maui County and the Big Island. Seas will remain around the advisory level (10 ft) over most waters into tonight before lowering Sunday through Monday as the large north-northwest swell lowers. As a result, a small craft advisory will remain up through tonight across most waters due to a combo of winds and seas, then across the windier zones through the day Sunday.

Surf along north and west facing shores will hold around advisory levels at least through the first half of the day before gradually lowering through the rest of the weekend as the swell eases. Observations at the PacIOOS nearshore buoys are remaining steady in the 9-12 ft range this morning, which is well above predicted levels. As a result, the high surf advisory has been extended through 6 pm today. Expect this source to shift out of a more northerly direction through the weekend as it fades.

A reinforcement out of the northwest is expected to fill in late Monday, peak Monday night into Tuesday, then fade through midweek. This source will be from a storm-force low that was depicted in the Thursday evening analysis over the far northwest Pacific near the western Aleutians. ASCAT data during this time showed a decent sized area of strong- to gale-force westerly winds associated with it focused at the islands within the 300-320 directional band. Guidance remains in decent agreement and shows this feature tracking eastward to the Date Line today. Surf associated with this source should remain below the advisory levels along north and west facing shores as it fills in and peaks early next week.

Surf along east facing shores will gradually rise over the weekend and early next week as the trades increase into the fresh to strong category, especially next Tuesday as trades reach the strong category across most waters. Limited fetch upstream of the state, however, should keep the surf below advisory levels for east facing shores through this time.

Small surf will continue along south facing shores with mainly background southern Pacific pulses moving through.

Hawaii Wave Height Model

Tide Predictions

Low tide at Kahului was 0.94 foot at 2:00 PM early this afternoon, rising to a high of 1.98 foot at 2:00 PM early this afternoon, then dropping to a low of 0.47 foot at 2:00 PM early this afternoon.

The sunrise was at 06:36 am this morning and will set at 05:45 pm this evening. The Moon is currently 9 days old, and is in a Waxing Gibbous phase. The next Full Moon will occur at 5:41 AM on Friday, November 23rd.

Hawaii Wind Report

Maui Weather

°/°
Wind: n/a at 0 mph
Sunrise:
Sunset:
current observations as of 6pm January 15th, 2019

Weather Outlook for Saturday, 17th November 2018

Summary

Breezy trade winds will persist into early next week. A weakening frontal boundary moving down across the state will bring numerous showers and the possibility of a heavy downpour across windward sections this weekend. In addition, the strong trades will carry brief showers to leeward sections of the smaller islands through tonight. Showers are expected to be most active over Kauai, Oahu and Moloka`i today, across Maui through this evening, and on the Big Island from tonight into Sunday. The trades may become locally windy next Tuesday and Wednesday.

Detailed Discussion

The tight pressure gradient south of a 1026 mb surface high near 32N 163W, or about 750 miles north-northwest of Lihue, is producing breezy northeasterly trade winds across the state early this morning. The high is also pushing a band of low clouds and showers associated with a weakening frontal boundary down across western end of the island chain. Mid- and upper-level troughs near the western islands is causing some atmospheric instability. As a result, the showers along and ahead of the frontal boundary are somewhat enhanced. This is resulting in widespread rainfall over windward and mauka areas, especially on Kauai, Oahu, Moloka`i and the windward Big Island. In addition, the strong trades are transporting brief trade showers over to some leeward sections of Kauai, Oahu and Moloka`i. Also, high clouds continue to stream across most of the islands east of Oahu.

The forecast guidance indicates the surface high will continue to move east through this weekend. This will push the weakening frontal boundary over Oahu this morning, and across portions of Maui County into this evening. The boundary will eventually move across the Big Island from tonight through Sunday, before moving south of the Big Island by Monday. The troughs aloft will gradually propagate eastward and weaken through Sunday. This will maintain slight instability across the area, which will continue to enhance the low clouds and showers, especially along the remnant frontal band. This could result in brief locally heavy downpours over some windward areas. We do not anticipate significant flooding, but we will closely monitor radar data and rain gages in case some areas have localized ponding of water on roads or brief periods of elevated water levels in streams or drainage systems. The breezy trades will also continue to transport a few showers over to leeward sections of some of the smaller islands through tonight.

As the troughs aloft continue to shift slowly eastward, the high clouds will eventually move east of the state. In the meantime, moisture associated with the frontal boundary combined with the cold pool aloft due to the mid-level trough has the potential to produce brief periods of winter weather on the Big Island Summits, mainly on Sunday. At the moment, we do not have significant accumulations of ice or snow in the forecast.

The surface high will track slowly east to a position far north of the islands Monday. The low-level east-northeast trade flow will continue to deliver passing low clouds and showers to windward areas from Monday through mid-week. A new surface high building far north of the state will likely cause additional strengthening of the trades starting Tuesday. This may produce locally windy trade winds Tuesday and Wednesday. Later next week, the winds may diminish and veer around to the southeast. In addition, showers may increase again as an upper-level low develops west of the islands.

Central Valley (Kahului, Spreckelsville):

HIGH SURF ADVISORY IN EFFECT UNTIL 6 PM HST THIS EVENING. Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 79 to 85. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Leeward West (Lahaina, Ka`anapali):

Mostly cloudy in the evening then becoming partly cloudy. Breezy. Scattered showers. Lows 68 to 74. Northeast winds 20 to 25 mph. Chance of rain 50 percent.

Windward West (Wailuku, Waiehu):

HIGH SURF ADVISORY IN EFFECT UNTIL 6 PM HST THIS EVENING. Breezy. Mostly cloudy with showers likely. Highs 66 to 81. Northeast winds 15 to 25 mph. Chance of rain 70 percent.

Windard Haleakala (Hana, Haiku, Makawao):

HIGH SURF ADVISORY IN EFFECT UNTIL 6 PM HST THIS EVENING. Mostly cloudy with showers likely. Highs around 78 at the shore to around 65 at 5000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Leeward Haleakala (Kihei, Wailea, Makena):

Breezy. Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 70 at the shore to 53 to 59 upcountry. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Haleakala Summit

Breezy. Mostly cloudy with scattered showers. Lows around 46 at the visitor center to around 42 at the summit. East winds 10 to 20 mph. Chance of rain 50 percent.