High Surf Advisory

...HIGH SURF ADVISORY FOR NORTH AND WEST FACING SHORES OF NIIHAU KAUAI OAHU AND MOLOKAI AND FOR NORTH FACING SHORES OF MAUI... .A large north-northwest swell will build on Tuesday and continue through Wednesday, producing dangerously high surf along exposed north and west facing shores. ...HIGH SURF ADVISORY IN EFFECT FROM 9 AM TUESDAY TO 6 PM HST

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2-4 foot
0-2 foot
1-2 foot
0-0 foot

Light winds will continue through much of the weekend as a front approaches and moves into the area from the northwest. Near the coasts, expect land and sea breezes to continue. Showers and thunderstorm coverage will begin to shift eastward and focus over Maui County and the Big Island by tonight and Sunday. A gradual drying trend with light to moderate northerly winds filling in is anticipated over Oahu and Kauai come Sunday as the front makes its way down the island chain and dissipates. Moderate northerly winds will continue to fill in late Sunday, then veer to a more typical trade wind direction and strengthen into the moderate to fresh range across all waters Sunday night through midweek as high pressure builds to the north.

The large south-southwest swell that peaked Thursday will slowly ease over the weekend. Recent nearshore PacIOOS buoy observations at Lanai and Barbers continue to reflect a decent amount of energy within the lower frequency bands (18-22 and 16-18 sec), which will likely translate to this source holding through the day today before lowering further through the second half of the weekend. A reinforcement (slightly smaller) out of the same direction is expected to fill in by the end of the day today. This will hold through Sunday, then slowly lower through the first half of the week. As a result, surf along south facing shores will remain up near advisory levels through Monday.

Surf along north and west facing shores will continue to lower today as the current north-northwest swell eases. A small reinforcement will fill in Sunday, which will support small to moderate breakers through Monday. A much larger source is expected Tuesday through midweek, which will likely exceed advisory levels for north and west facing exposures. This source will be associated with a storm currently evolving over the far northwest Pacific. The latest ensemble guidance remains in good agreement and depicts a large batch of gale- to storm-force winds setting up within the 320-340 directional band relative to the islands through the weekend. WAVEWATCH III and ECMWF-Wave guidance reflect this and show seas climbing into the 25 to 35 ft range. Long- period forerunners associated with this source will begin to move into the area late Monday night into Tuesday, peak late Tuesday through early Wednesday, then slowly lower Thursday through Friday.

Surf along east facing shores will remain small through the weekend as the Sergio swell continues to fade (mainly eastern islands). Expect this trend to continue through the upcoming week as the upstream trades remain cutoff.

Hawaii Wave Height Model

Tide Predictions

High tide at Kahului was 2.26 foot at 2:00 PM early this afternoon, dropping to a low of 1.13 foot at 2:00 PM early this afternoon, then rising to a high of 1.42 foot at 2:00 PM early this afternoon, before once again dropping to a low of 0.24 foot at 2:00 PM early this afternoon.

The sunrise was at 06:19 am this morning and will set at 06:03 pm this evening. The Moon is currently 5 days old, and is in a Waxing Crescent phase. The next First Quarter will occur at 6:02 PM on Tuesday, October 16th.

Hawaii Wind Report

Maui Weather

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Wind: n/a at 0 mph
Sunrise:
Sunset:
current observations as of 4pm October 15th, 2018

Weather Outlook for Saturday, 13th October 2018

Summary

An upper level trough out of the northwest will sweep eastward across the Hawaiian Islands over the next 24 hours enhancing shower activity statewide through Saturday. Isolated thunderstorms will develop with periods of heavy rainfall likely. Wet weather continues into Wednesday as a weak cold frontal band moves into the state from the northwest on Sunday. Trade winds return behind the front across the region from Sunday onward. Elevated moisture and lingering instability will continue to enhance showers statewide favoring windward and mountain areas through Thursday. A brief drying trend returns by Friday.

Detailed Discussion

Scattered to numerous showers remain in the offshore waters of each island from Oahu to the Big Island this morning. Land breezes overnight helped to diminish overnight shower coverage over each island from Kauai to Maui with light shower activity continuing over the Big Island.

A low pressure system over the Central Pacific continues to bring wet weather to the Hawaiian Islands through the weekend. An upper level short wave trough will move through the islands from northwest to southeast today bringing frequent rain showers, heavy at times, with isolated thunderstorms from Oahu to the Big Island. A surface trough has developed in response to this upper level feature, pumping up moisture from the deep tropics into the islands with Precipitable Water (PW) levels ranging from 1.5 to 2.0 inches from Oahu to the Big Island.

Drier more stable air aloft will slowly filter into the islands from west to east decreasing shower activity as the trade wind subsidence inversion caps vertical cloud development. This stable air aloft has already reached Kauai, with the trade wind subsidence inversion evident in this mornings 12Z upper air sounding at around 8000 feet elevation. A Flash Flood Watch remains in effect through midnight tonight from Oahu eastward to the Big Island. This Flash Flood Watch will probably decrease in coverage later today over the western half of the state as the drier stable air aloft reaches Oahu.

A shallow surface cold front will drift into the Hawaiian Islands from the northwest on Sunday with the low level convergence in the returning trade wind flow creating additional showers over the islands. Light synoptic scale winds will allow afternoon onshore sea breezes to continue for most islands through Sunday. Trade winds will increase in strength behind the frontal trough as it passes into the region by Sunday night. Forecast models show this shallow frontal boundary stalling over the state keeping moisture over the islands through the first half of next week.

Expect lingering moisture and instability to stick around through Thursday. Which means a wet trade wind shower regime from Sunday night onward will produce elevated showers favoring windward and mountain slopes with more isolated showers remaining in the forecast for leeward areas.

A brief drying trend is favored by long range forecast models to develop by next Friday and Saturday ahead of another shallow cold front approaching the islands from the north. Stay tuned.

Central Valley (Kahului, Spreckelsville):

FLASH FLOOD WATCH IN EFFECT THROUGH THIS EVENING. Cloudy with numerous showers and isolated thunderstorms. Locally heavy rainfall possible. Highs around 84. Southwest winds up to 10 mph. Chance of rain 70 percent.

Leeward West (Lahaina, Ka`anapali):

FLASH FLOOD WATCH IN EFFECT THROUGH THIS EVENING. Cloudy with numerous showers and isolated thunderstorms. Locally heavy rainfall possible. Highs 80 to 85. Southwest winds up to 10 mph. Chance of rain 70 percent.

Windward West (Wailuku, Waiehu):

FLASH FLOOD WATCH IN EFFECT THROUGH THIS EVENING. Cloudy. Numerous showers and isolated thunderstorms in the morning, then frequent showers and isolated thunderstorms in the afternoon. Locally heavy rainfall possible. Highs 68 to 83. Light winds. Chance of rain 90 percent.

Windard Haleakala (Hana, Haiku, Makawao):

FLASH FLOOD WATCH IN EFFECT THROUGH THIS EVENING. Cloudy. Numerous showers and isolated thunderstorms in the morning, then frequent showers and isolated thunderstorms in the afternoon. Locally heavy rainfall possible. Highs around 80 at the shore to around 67 at 5000 feet. Light winds. Chance of rain 90 percent.

Leeward Haleakala (Kihei, Wailea, Makena):

FLASH FLOOD WATCH IN EFFECT THROUGH THIS EVENING. Cloudy. Numerous showers and isolated thunderstorms in the morning, then frequent showers and isolated thunderstorms in the afternoon. Locally heavy rainfall possible. Highs around 84 at the shore to 68 to 74 upcountry. Light winds becoming southwest up to 10 mph in the afternoon. Chance of rain 80 percent.

Haleakala Summit

FLASH FLOOD WATCH IN EFFECT THROUGH THIS EVENING. Cloudy. Numerous showers and isolated thunderstorms in the morning, then frequent showers and isolated thunderstorms in the afternoon. Locally heavy rainfall possible. Highs around 59 at the visitor center to around 55 at the summit. Southwest winds around 10 mph. Chance of rain 90 percent.

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