Photo Credit: Travis Guthrie

West Side

Today: Breezy. Mostly sunny with isolated showers. Highs 78 to 85. Northeast winds 20 to 25 mph. Chance of rain 20 percent.

Tonight: Windy. Partly cloudy with isolated showers. Lows 65 to 71. Northeast winds 25 to 30 mph decreasing to 10 to 25 mph after midnight. Chance of rain 20 percent.

Tuesday: Mostly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 78 to 85. East winds 10 to 20 mph. Chance of rain 40 percent.

South Side

Today: Sunny and breezy. Highs around 84. Northeast winds 10 to 25 mph.

Tonight: Mostly clear. Breezy. Lows around 66. Northeast winds 10 to 20 mph.

Tuesday: Sunny and breezy. Highs around 84. East winds 15 to 25 mph.

North Shore

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 75 to 81 near the shore to around 63 near 5000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with numerous showers. Lows 63 to 69 near the shore to around 51 near 5000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Tuesday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 81 near the shore to around 63 near 5000 feet. East winds 15 to 20 mph. Chance of rain 70 percent.

Central Maui

Today: Sunny and breezy. Highs 80 to 85. Northeast winds 15 to 25 mph.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows around 66. Northeast winds 10 to 25 mph. Chance of rain 50 percent.

Tuesday: Breezy. Mostly sunny with isolated showers. Highs 80 to 85. East winds 15 to 25 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 56 at the visitor center to around 54 at the summit. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Partly cloudy with scattered showers. Lows around 44 at the visitor center to around 40 at the summit. East winds 10 to 25 mph. Chance of rain 50 percent.

Tuesday: Breezy. Mostly sunny with scattered showers. Highs around 57 at the visitor center to around 55 at the summit. East winds 10 to 25 mph. Chance of rain 50 percent.

East Maui

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 75 to 81 near the shore to around 63 near 5000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with numerous showers. Lows 63 to 69 near the shore to around 51 near 5000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Tuesday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 81 near the shore to around 63 near 5000 feet. East winds 15 to 20 mph. Chance of rain 70 percent.

Lanai City

Today: Breezy. Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 73 to 80. Northeast winds 15 to 25 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows around 65. Northeast winds 15 to 25 mph. Chance of rain 20 percent.

Tuesday: Breezy. Mostly sunny with isolated showers. Highs 72 to 79. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Kaunakakai

Today: Sunny and breezy. Isolated showers in the afternoon. Highs 76 to 84. Northeast winds 15 to 25 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Scattered showers in the evening, then isolated showers after midnight. Lows 63 to 72. Northeast winds 15 to 25 mph. Chance of rain 50 percent.

Tuesday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 75 to 83. East winds 15 to 25 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Trade winds will continue to strengthen, becoming breezy and gusty through Wednesday as a strong high develops north of the state. An upper trough may produce periods of locally enhanced rainfall. Showers will favor windward slopes. Expect afternoon rainfall across leeward and interior Big Island areas. Trade winds will ease to moderate strength Thursday into next weekend.

Discussion

A strong high far northwest of Kauai will build eastward and drive strengthening trade winds for the next few days. A weakening front north of the islands will work to counteract the high's trade-strengthening impact, but trades will slowly increase anyway. Expect breezy and gusty trade winds through Wednesday. The high far north of the state will strengthen to about 1040 mb on Tuesday as the intervening front dissipates, making local trade winds quite strong. Upper troughing will linger and, while conditions are not expected to be significantly unstable, models suggest that the inversion will be weak or absent. This will work to enhance showers. Rainfall will favor windward areas, with enhanced afternoon clouds and shower activity becoming more extensive over leeward and interior Big Island. Periods of thin high clouds will continue.
Trades will ease Thursday as the high to the north weakens. Models suggest a simultaneous but brief instability boost. This could raise chances of thunderstorms, mainly on the Big Island slopes, and shower activity in the trade flow could become enhanced. Moderate trade winds and more stable conditions are expected Friday into next weekend.

Aviation

A high pressure ridge far north of the state will produce moderate to locally breezy trade winds across the Hawaii region through Monday. An upper level trough will enhance shower activity mainly in the windward and mountain areas, favoring the overnight to early morning hours. Periods of MVFR conditions are forecast over windward airfields with prevailing VFR over most leeward sites.
AIRMET Sierra for mountain obscuration remains in effect for north through east sections from Kauai to Maui. These conditions will likely continue through the early morning hours.
AIRMET Tango remains in effect for moderate low level turbulence over and south through west of mountains for all islands. AIRMET Tango is also in effect for moderate to isolated severe turbulence over the islands as a subtropical jet stream approaches from the west.
Occasional light icing in layered clouds will also remain in the forecast. Conditions are mostly likely across Kauai and Oahu.

Marine

High pressure north of the state will build eastward and drive the increasing trades through mid- week, peaking at near- gales in the windiest zones Tuesday into Wednesday, then gradually weakening from Thursday onward. A Small Craft Advisory (SCA) remains in effect for the typical windy zones and has expanded over waters around Kauai and Oahu. The SCA may need to be expanded as trade winds strengthen across the waters.
A small to moderate north (350 deg) swell has begun to rise slightly over the offshore buoys, resulting in building surf for north- facing shores this afternoon with a peak on Tuesday. Surf levels are forecast to approach but not reach the High Surf Advisory (HSA) threshold on Tuesday. East facing shores will have short period trade wind swell from building trades and may also see a slight rise for selective spots exposed to the north swell. A small medium period northwest (320 deg) swell is possible at the end of the week. South-facing exposures will continue to have minimal surf due to long period south swells throughout the week.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov