Photo Credit: Tyler Rooke

West Side

Today: Mostly sunny. Breezy. Highs 78 to 86. East winds 10 to 20 mph.

Tonight: Mostly clear. Breezy. Lows 67 to 73. Northeast winds 10 to 20 mph.

Tuesday: Breezy. Sunny with isolated showers. Highs 76 to 84. Northeast winds 10 to 20 mph. Gusts up to 40 mph in the morning. Chance of rain 20 percent.

South Side

Today: Sunny and breezy. Highs around 87. East winds 10 to 20 mph.

Tonight: Mostly clear. Breezy. Lows 64 to 73. Northeast winds 10 to 20 mph.

Tuesday: Sunny and breezy. Highs around 84. Northeast winds 10 to 20 mph.

North Shore

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 76 to 85 near the shore to around 68 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows around 69 near the shore to 47 to 53 near 5000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Tuesday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 83 near the shore to around 66 near 5000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Central Maui

Today: Mostly sunny. Breezy. Highs 84 to 89. East winds 10 to 20 mph.

Tonight: Mostly clear. Breezy. Lows 64 to 70. East winds 10 to 20 mph.

Tuesday: Sunny and breezy. Highs 80 to 85. Northeast winds 10 to 20 mph.

Upcountry

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 63 at the visitor center to around 58 at the summit. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 48 at the visitor center to around 45 at the summit. East winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 61 at the visitor center to around 56 at the summit. East winds 10 to 15 mph shifting to the northeast 15 to 25 mph in the afternoon. Chance of rain 50 percent.

East Maui

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 76 to 85 near the shore to around 68 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows around 69 near the shore to 47 to 53 near 5000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Tuesday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 83 near the shore to around 66 near 5000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Lanai City

Today: Mostly sunny. Highs 73 to 80. Northeast winds 10 to 15 mph.

Tonight: Mostly clear. Lows around 65. Northeast winds 10 to 15 mph.

Tuesday: Sunny and breezy. Highs 71 to 78. Northeast winds 10 to 25 mph.

Kaunakakai

Today: Mostly sunny. Breezy. Highs 68 to 88. East winds 10 to 20 mph.

Tonight: Mostly clear. Breezy. Lows 56 to 72. East winds 10 to 20 mph.

Tuesday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 66 to 85. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Ridging north of the islands will maintain moderate to locally breezy trade winds today, with isolated to scattered showers generally favoring windward and mauka areas. Stronger northeast trade winds are expected to build across the area Tuesday afternoon, and then persist through at least Thursday night. Shower chances will also increase across the islands from west to east Tuesday though Thursday morning before drier air returns statewide by Thursday afternoon. A return to more typical trade wind weather is expected from Friday through the weekend.

Discussion

No significant changes to the forecast this morning. High pressure remains far northeast of the islands with a ridge extending from the high to the northern boundary of the offshore waters. Moderate to locally breezy trade winds have spread across the region as a result. CIMSS MIMIC layer precipitable water (PW) shows precipitable water values have become more uniform across the islands. This correlates well with the overnight soundings which show Lihue at 1.40 inches, and Hilo 1.49 inches of PW. Much drier air is noted further northwest near Kauai closer to the ridge axis.
Moderate to locally breezy trade winds are expected to continue today, with showers favoring the windward and mauka areas. Expect drier air to spread over the eastern end of the state later today.
As a front passes north of the islands on Tuesday, moisture will once again increase over and upstream of the islands. Strong post- frontal high pressure will also begin to increase winds to locally strong levels by Tuesday afternoon, and these locally strong winds will persist through at least Thursday night. As the high pressure strengthens north of the state, moisture associated with another front will be pushed down the island chain, increasing shower chances from west to east Tuesday night through Thursday morning.
Much drier air will fill in across the state from west to east on Thursday. More typical trade wind weather with moderate to locally breezy trades and showers favoring windward and mauka locations will return from Friday through the weekend.

Aviation

Moderate to locally breezy trades will continue through the next 24 hours, with only a temporary diurnal weakening across the state during the overnight hours. Low clouds and showers will cause windward Big Island to continue to experience MVFR conditions early this morning, with only brief periods of MVFR conditions expected across other windward areas. Otherwise, VFR conditions will prevail.
AIRMET Sierra for mountain obscuration across windward Big Island remains in effect early this evening. However, drier air has filtered in and allowed conditions to improve slightly, so this AIRMET might be dropped later this morning. Satellite imagery, radar and surface observations show some low clouds and showers beginning to persist over windward Oahu this morning and if this activity becomes more extensive, windward Oahu may need to be included in the AIRMET Sierra for mountain obscuration.

Marine

A surface ridge sitting nearly 250 nm north of Kauai will maintain moderate to locally strong trade winds through today. A Small Craft Advisory (SCA) is in place for the typically windy waters around the Big Island and Maui. Winds should ease slightly and become northeasterly around Kauai this afternoon and evening as a front approaches from the northwest followed closely by a strong high pressure. As the weak front reaches Kauai late Tuesday or early Wednesday, the robust surface high to the northwest will drive increasing northeasterly trade winds and large rough seas. The SCA has been expanded to all waters Tuesday due to strengthening winds and building seas. This SCA may very well be expanded for most waters, if not all, as the high settles north of the area Friday and seas remain elevated. A decrease in trade winds is expected heading into next weekend, but SCA conditions could persist.
Latest near shore buoys show the 340-350 degree north-northwest swell of around 5 ft at 12 seconds has shifted to a more northerly (350-010 degrees) direction at around 4 ft 12 seconds and will continue to slowly decline through today. Since this swell is trending down, the threat of moderate surges in Kahului and Hilo harbors no longer posses a threat thus the Marine Weather Statement has been allowed to expire. Long- period forerunners from the next northwest swell will arrive early Tuesday, and the swell will peak at 9 to 10 ft Tuesday night and Wednesday. While the resulting surf will easily exceed High Surf Advisory levels on north and west facing shores, the peak of the swell will coincide with fresh to near gale northeasterly winds, leading to rough conditions and the potential for high surf along east facing shores due to large wind waves. On Thursday, the swell will shift out of the north- northwest and may be briefly reinforced, keeping surf elevated around advisory levels. The northerly swell is expected to decline late Friday into the weekend.
Small short-period wind waves and small wrapping northerly swell will produce moderate east shore surf through today, followed by a rise to around the advisory level Tuesday and Wednesday as strengthening northeasterly trade winds produce large wind waves. Above average east shore surf and rough conditions can be expected Thursday and Friday due to fresh to near gale trade winds and additional wrapping northerly swell. A small pulse of south- southwest swell will fill in late Monday into Tuesday.

HFO Watches/Warnings/Advisories

Small Craft Advisory from 6 AM Tuesday to 6 AM HST Wednesday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.
Small Craft Advisory until 6 AM HST Wednesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov