Photo Credit: Pamela Goguen Lynch

West Side

Today: Sunny and breezy. Highs 79 to 87. Northeast winds 10 to 20 mph.

Tonight: Mostly clear. Breezy. Lows 62 to 68. Northeast winds 15 to 20 mph.

Thursday: Sunny and breezy. Highs 79 to 87. East winds 10 to 20 mph.

South Side

Today: Sunny and breezy. Highs 83 to 89. Northeast winds up to 15 mph shifting to the north in the afternoon.

Tonight: Mostly clear. Lows around 64. North winds up to 15 mph shifting to the northeast after midnight.

Thursday: Sunny. Highs 83 to 89. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon.

North Shore

Today: Breezy. Mostly sunny with isolated showers. Highs 79 to 84 near the shore to around 65 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 62 to 67 near the shore to around 50 near 5000 feet. East winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 20 percent.

Thursday: Breezy. Mostly sunny with isolated showers. Highs 79 to 84 near the shore to around 66 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Central Maui

Today: Sunny and breezy. Highs 84 to 89. Northeast winds 10 to 20 mph.

Tonight: Mostly clear. Lows around 64. Northeast winds 10 to 15 mph.

Thursday: Sunny. Highs 84 to 89. Northeast winds 10 to 15 mph.

Upcountry

Today: Sunny with isolated showers. Highs around 61 at the visitor center to around 59 at the summit. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Mostly clear with isolated showers. Lows around 46 at the visitor center to around 43 at the summit. East winds 10 to 15 mph. Chance of rain 20 percent.

Thursday: Sunny. Isolated showers in the morning. Highs around 62 at the visitor center to around 60 at the summit. East winds 10 to 15 mph. Chance of rain 20 percent.

East Maui

Today: Breezy. Mostly sunny with isolated showers. Highs 79 to 84 near the shore to around 65 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 62 to 67 near the shore to around 50 near 5000 feet. East winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 20 percent.

Thursday: Breezy. Mostly sunny with isolated showers. Highs 79 to 84 near the shore to around 66 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Lanai City

Today: Sunny and breezy. Highs 70 to 79. Northeast winds 10 to 20 mph.

Tonight: Mostly clear. Lows around 64. Northeast winds 10 to 15 mph.

Thursday: Sunny. Highs 70 to 79. East winds 10 to 15 mph.

Kaunakakai

Today: Sunny and breezy. Highs 73 to 83. Northeast winds 10 to 20 mph.

Tonight: Mostly clear. Breezy. Lows 59 to 69. Northeast winds 10 to 20 mph.

Thursday: Sunny and breezy. Highs 73 to 83. East winds 15 to 20 mph.

Detailed Forecast

Synopsis

Moderate to locally breezy trade winds are expected through Thursday. Conditions will be rather dry, with brief trade showers mainly along some windward facing sections late at night and during the early morning hours. The background trade flow will begin to weaken and shift around from the east-southeast this weekend. This will allow local afternoon sea breezes to develop with clouds and isolated showers mainly over leeward and interior sections.

Discussion

A 1021 mb surface high pressure system is near 32N 163W, or about 780 miles north-northwest of Honolulu. This feature is moving toward the east at 10 to 15 mph, so it will be due north of the islands in about 24 hours. This is causing the pressure gradient to tighten over the state, so moderate to locally breezy easterly trade winds are expected during the next 36 hours or so.
The atmosphere over the islands remains dry and stable. Loops of infrared satellite imagery show patches of stable low clouds upwind of Maui and the Big Island. There are also scattered to locally broken low clouds along some windward sections of the Big Island, and scattered low clouds over portions of windward Oahu and Kauai. Radar reflectivity data indicate there are a few light showers embedded within some of the low clouds. Overall, tranquil weather conditions appear to be the rule across the Aloha State early this morning.
The forecast guidance shows the surface high will eventually move far northeast of the state from late Thursday night through Friday. This will cause the trade winds to begin to weaken slightly. The stable and dry atmospheric conditions will also remain in place, so there will be some low clouds and brief trade showers along windward sections. The trade showers will tend to be most prevalent during the late night and early morning hours. The upslope sections of the leeward Big Island will continue to have clouds and a few showers during the afternoon and early evening hours.
As we head into the weekend, a surface front will move toward the region from the northwest. This will likely cause additional weakening of the background flow, with light and variable winds over the western half of the state, and light to locally moderate east to east-southeast winds over the eastern half of the state by Sunday. In addition, a weak mid-level trough may develop in the vicinity of the islands, while a mid- and upper-level trough will dig down toward the region from the northwest. The main influence we currently anticipate with the troughing aloft will be to increase the high clouds over portions of the state as a sub- tropical jet sets up. The lighter background winds will also allow the establishment of a pattern of afternoon sea breezes and nighttime land breezes. This may produce some clouds and isolated showers over leeward and interior sections during the afternoon and early evening hours. The overall rainfall amounts should remain modest, since there does not appear to be any significant increase in moisture.

Aviation

Dry and stable trade wind pattern will result in VFR conditions prevailing through much of the 24-hour period. Brief periods with MVFR conditions can't be ruled out in and around passing showers this morning.
There are currently no AIRMETs.

Marine

he subtropical ridge will remain in place north of the islands into the weekend, producing gentle to moderate easterly trade winds for most areas through Saturday. Wind speeds today will exceed Small Craft Advisory (SCA) criteria for the windier eastern waters and channels through Thursday morning and an SCA was issued for these areas. A cold front approaching the region from the northwest on Sunday will weaken the ridge north of the islands, causing the trade winds to weaken over the western islands. Moderate to locally breezy easterly trade winds return on early next week with wind speeds over the eastern windier areas approaching SCA thresholds.
Surf heights along south facing shores will remain on the small side today. However, two rather large south swells generated over the waters just east of New Zealand are on the way to the Hawaiian Islands. The forerunners of the first large south swell will arrive on Thursday, increasing surf heights as the swell builds along south facing shores of all islands to low end High Surf Advisory (HSA) levels from Friday through Saturday. This swell energy begins to slowly decline from Saturday night to Sunday, before the forerunners of the next swell begins to hit south facing shores by Sunday night. This next large south swell will quickly build south shore surf heights to HSA levels by Monday and then peak near High Surf Warning levels on Tuesday.
Surf along north and west facing shores will get a small, short- period bump through Thursday, with declining surf heights on Friday. Another medium period west-northwest swell (300 degrees) arrives on Saturday producing a small increase in north and west shore surf heights into the weekend, before declining into the first half of next week. Surf heights along east facing shores will remain small and choppy through the week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Thursday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov