6-8+ foot
4-6+ foot
0-2 foot
5-8 foot

Fresh to locally strong trade winds are expected to continue through most of the week, particularly in the channels and in the waters south of the Big Island, where Small Craft Advisory levels are expected. A series of north-northwest swells will be arriving in the islands over the next several days, which will help to keep combined seas above the SCA levels through the week. Winds in Maalaea Bay are expected to drop below SCA levels by tonight, and will be sheltered from the incoming swells. However winds may pick up in the bay later in the week.

The trade winds continue to produce low end advisory level surf along the east facing shores. Currently expecting a bit of a decrease in the trade wind swell tonight and tomorrow, however surf is expected to remain near advisory levels through much of the week.

A new north-northwest swell is expected to build today. Some long period energy has been seen at the buoys to the northwest of the islands, and that energy is expected to reach the islands later this morning. This swell is expected to peak at near advisory levels for the north and west facings shores tonight. A High Surf Advisory may be needed later today for this swell, which is expected to persist into tomorrow.

A larger north-northwest swell is expected to build Wednesday, and peak Thursday. This swell will bring advisory level surf to the affected shores, and could bring warning level surf to the north facing shores.

A high amount of uncertainty remains around the weather forecast for the upcoming weekend. Please stayed tuned to later discussions for mention of wind and local wave forecasts.

Hawaii Wave Height Model

Tide Predictions

Low tide at Kahului was 1.0 foot at 2:00 PM early this afternoon, rising to a high of 2.0 foot at 2:00 PM early this afternoon, then dropping to a low of 0.3 foot at 2:00 PM early this afternoon, before once again rising to a high of 1.8 foot at 2:00 PM early this afternoon

The sunrise was at 06:44 am this morning and will set at 05:44 pm this evening. The Moon is currently 9 days old, and is in a Waxing Gibbous phase. The next Full Moon will occur at 3:48 PM on Sunday, December 3rd.

Hawaii Wind Report

Maui Weather

65°/°
Wind: SE at 5 mph
Sunrise: 6:52 AM
Sunset: 5:45 PM
current observations as of 3am December 11th, 2017

Weather Outlook for Tuesday, 28th November 2017

Summary

Locally breezy trade winds are expected for at least the next couple days. The trade winds will continue to deliver abundant showers to windward portions of Maui and the Big Island, with this moisture expected to spread to the other islands Thursday and Friday. Some decrease in shower coverage is possible over the weekend. High clouds will thin out a little tonight and Wednesday only to thicken again Thursday and Friday.

Detailed Discussion

A 1032 mb surface high centered about 1200 miles to the NE of the islands is supporting strong and locally gusty E trade winds, while a moist and nearly saturated air mass (PWAT > 2″) is in place over the Big Island and Maui. A broad and slow-moving trough aloft extends across a large portion of the tropical central north Pacific, extending from N of the islands to well SW of the islands. Diffluent flow E and SE of the trough axis is resulting in overcast mid and high level clouds over a large area, including the Hawaiian Islands, although these clouds have thinned some since yesterday.

Overnight, rainfall rates have been averaging a steady .50″/hour at many of the gages on windward Big Island/Maui, with 24 hour rainfall totals between 6 and 9 inches. Trade wind showers have been less productive elsewhere, but over 2″ of rain has been reported from wetter locations on Kauai (Kilohana near Kokee) and Oahu (Manoa valley). Temperatures have been dipping above and below the freezing mark over the Big Island summits overnight, where a wintry mix of snow and rain is likely occuring. A Monday evening ranger report indicated areas of slushy snow and ice on summit roadways. With more snow expected today, the ongoing Winter Storm Warning (WSW) remains in effect.

UW-CIMSS MIMIC2 total precipitable water imagery shows deep moisture (PWAT of 2 inches of higher) extending well E and SE of the islands. Forecast models indicate relatively strong trade winds (with some subtle variations) to continue through most of the week, supported by a pair of highs to the NE and NW of the islands by midweek. Deep moisture near Maui and the Big Island is expected to slide NW up the island chain, but latest guidance indicates this won’t happen until Thursday/Friday. Given the recent rainfall totals, and the expectation that showery weather will continue with the potential for heavier downbursts, the Flash Flood Watch (FFA) for Maui and the Big Island will remain in effect today.

The trough aloft currently near the islands is forecast to weaken and slide E of the islands later tonight and Wednesday, leading to some thinning of the high clouds as well as some increase in stability. The deep moisture will remain near Maui and the Big Island, and although the atmosphere will be only moderately unstable, windward areas will likely receive a steady barrage of showers. Whether or not a continuation of the FFA will be warranted remains a question as showers will be moving along with the trades, but may be sufficiently incessant to result in significant stream rises and/or flash-flooding. Warming summit temperatures may allow the WSW to be dropped later today, but confidence is low.

From late Wednesday into Friday, a new trough aloft will sharpen to the W of the islands, effectively allowing the area of deep moisture to spread over all islands. The latest solution from a wildly- varying set of model guidance indicates that surface cyclogenesis will be subdued and well SW of the islands (as compared to recent ECWMF runs which indicated a strong Kona low just W of the islands). While these latest solutions keep a wet weather pattern over the islands through about Saturday, the low-level winds would be from the E/SE. The sharpening trough aloft will likely lead to thickening high clouds Thursday and Friday.

A drying trend is now indicated by GFS/ECMWF for the weekend as a ridge aloft builds over the area from the NW, but given recent run- to-run volatility in guidance, confidence in the weekend forecast still remains low.

Central Valley (Kahului, Spreckelsville):

FLASH FLOOD WATCH IN EFFECT THROUGH THIS AFTERNOON. Windy. Mostly cloudy with scattered showers. Locally heavy rainfall possible. Highs 78 to 83. Northeast winds 15 to 20 mph increasing to 20 to 30 mph in the late morning and afternoon. Gusts up to 45 mph. Chance of rain 50 percent.

Leeward West (Lahaina, Ka`anapali):

FLASH FLOOD WATCH IN EFFECT THROUGH THIS AFTERNOON. Breezy. Mostly cloudy with scattered showers. Locally heavy rainfall possible in the afternoon. Highs 76 to 82. Northeast winds 15 to 25 mph. Chance of rain 40 percent.

Windward West (Wailuku, Waiehu):

HIGH SURF ADVISORY IN EFFECT UNTIL 6 PM HST THIS EVENING… …FLASH FLOOD WATCH IN EFFECT THROUGH THIS AFTERNOON. Breezy. Mostly cloudy with scattered showers. Locally heavy rainfall possible. Highs 64 to 80. Northeast winds 15 to 25 mph. Chance of rain 50 percent.

Windard Haleakala (Hana, Haiku, Makawao):

HIGH SURF ADVISORY IN EFFECT UNTIL 6 PM HST THIS EVENING… …FLASH FLOOD WATCH IN EFFECT THROUGH THIS AFTERNOON. Breezy. Cloudy with occasional showers. Locally heavy rainfall possible. Highs around 78 at the shore to around 64 at 5000 feet. East winds 15 to 25 mph with gusts to 40 mph. Chance of rain 90 percent.

Leeward Haleakala (Kihei, Wailea, Makena):

FLASH FLOOD WATCH IN EFFECT THROUGH THIS AFTERNOON. Breezy. Mostly cloudy with scattered showers. Locally heavy rainfall possible in the afternoon. Highs around 82 at the shore to 64 to 69 upcountry. East winds 10 to 25 mph. Chance of rain 50 percent.

Haleakala Summit

Breezy. Mostly cloudy with scattered showers. Lows around 43 at the visitor center to around 39 at the summit. East winds 15 to 20 mph. Chance of rain 50 percent.

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