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High pressure northeast of the state will keep a moderate to locally strong trade wind flow in place through Saturday. As a result, a Small Craft Advisory remains in place for the typically windy waters around Maui County and the Big Island. An area of low pressure is expected to develop several hundred miles northwest of Kauai over the weekend, allowing the winds to weaken below SCA levels and shift around to the southeast Sunday through early next week.

Surf will remain below advisory levels along all shores through the middle of next week. Rough, short-period surf will remain around the summer average along east facing shores through tonight, then decline over the weekend. A north-northwest is expected late next week, which may bring moderate surf along north facing shores. Background south swells will keep surf below average along south facing shores through middle of next week. A small southwest swell is possible late next week.

Hawaii Wave Height Model

Tide Predictions

High tide at Kahului was 1.65 foot at 2:00 PM early this afternoon, dropping to a low of 0.20 foot at 2:00 PM early this afternoon, then rising to a high of 2.41 foot at 2:00 PM early this afternoon, before once again dropping to a low of 0.52 foot at 2:00 PM early this afternoon.

The sunrise was at 06:13 am this morning and will set at 06:22 pm this evening. The Moon is currently 12 days old, and is in a Waxing Gibbous phase. The next Full Moon will occur at 2:54 AM on Tuesday, September 25th.

Hawaii Wind Report

Maui Weather

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Wind: n/a at 0 mph
Sunrise:
Sunset:
current observations as of 8am December 12th, 2018

Weather Outlook for Saturday, 22nd September 2018

Summary

High pressure to the north and aloft will maintain a stable trade wind flow through Saturday night with clouds and showers favoring the windward and mountain areas. A low will form northwest of Kauai over the weekend and cause the winds to blow out of the southeast and south starting Sunday. This flow will bring in not only some humid weather but the potential for some unsettled weather to the western end of the island chain that may last through the first half of the new week.

Detailed Discussion

The trade winds are pretty much back, although there is slight south component over Oahu and Kauai. We will remain under this wind pattern through Saturday night. In the way of showers, radar is pretty quiet, only a few specks around, favoring mainly the windward and mountain areas. There are heavier showers, just to the south and west of Ni`ihau. It should stay off of Ni`ihau. The GFS solution is suggesting a somewhat drier than normal trade shower pattern for the main islands, including the normally wet windward Big Island through Saturday night.

Ridging aloft is helping put a lid over the islands with a low level inversion at 5 to 7k feet area wide. This inversion is expected to last through Sunday afternoon before breaking down due to the deep trough nudging closer to the islands. So, expect minimal shower activity over the weekend.

The latest GFS hint on the prolong rain to commence late Monday, which is in line with the old ECMWF run. Periods of scattered showers occur beforehand between Sunday and Monday mainly across Kauai. We shall see if this outlook shifts in the ensuing model runs. The unsettled weather can occur to other islands, not only Kauai. It all depend on the low cloud moisture and where it is located at. At a certain point, the forecast will likely include a slight chance of thunderstorms.

One thing for sure, the south to southeast winds will bring on a humid air mass to the islands that will likely last through the first half of next week. We are expecting dew point reaching into the mid 70s. The strength of the southeast/south winds during this stretch is light to moderate.

Currently, an upper low is located 823 miles NW of Kauai with the trough extending southwestward. At the surface, is an inverted trough, a reflecting of the trough aloft. It is a deep upper trough with an extensive broken to overcast layer of mid and high clouds, stretching eastward from the trough to the main Hawaiian Islands. Thunderstorms are noted some 260 miles west of Kauai. The GFS is hinting on thinning these layered clouds on Saturday, especially over the eastern half of the island chain.

Central Valley (Kahului, Spreckelsville):

Sunny and breezy. Highs 86 to 91. Northeast winds up to 20 mph.

Leeward West (Lahaina, Ka`anapali):

Sunny and breezy. Isolated showers in the morning. Highs 82 to 88. East winds up to 20 mph. Chance of rain 20 percent.

Windward West (Wailuku, Waiehu):

Breezy. Mostly sunny with scattered showers. Highs 71 to 86. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Windard Haleakala (Hana, Haiku, Makawao):

Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs around 82 at the shore to around 70 at 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Leeward Haleakala (Kihei, Wailea, Makena):

Sunny and breezy. Isolated showers in the afternoon. Highs around 88 at the shore to 70 to 77 upcountry. Southeast winds up to 20 mph. Chance of rain 20 percent.

Haleakala Summit

Sunny. Isolated showers in the afternoon. Highs around 60 at the visitor center to around 58 at the summit. East winds 10 to 15 mph. Chance of rain 20 percent.