Photo Credit: Tyler Rooke

West Side

Today: Sunny. Highs 72 to 78. Northeast winds up to 15 mph.

Tonight: Mostly clear. Isolated showers after midnight. Lows 61 to 68. Northeast winds up to 15 mph becoming around 10 mph after midnight. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs 71 to 77. Northeast winds up to 15 mph. Chance of rain 20 percent.

South Side

Today: Sunny. Highs around 79. North winds 10 to 15 mph.

Tonight: Mostly clear. Lows 60 to 69. North winds 10 to 15 mph.

Tuesday: Mostly sunny. Highs around 79. North winds 10 to 15 mph.

North Shore

Today: Sunny. Highs 73 to 78 near the shore to around 62 near 5000 feet. Northeast winds up to 15 mph.

Tonight: Partly cloudy with isolated showers. Lows around 64 near the shore to around 45 near 5000 feet. Northeast winds up to 10 mph shifting to the southeast after midnight. Chance of rain 20 percent.

Tuesday: Partly sunny with scattered showers. Highs around 75 near the shore to around 60 near 5000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Central Maui

Today: Sunny. Highs around 78. Northeast winds 10 to 15 mph.

Tonight: Mostly clear. Lows 60 to 65. Northeast winds around 10 mph.

Tuesday: Mostly sunny with isolated showers. Highs 74 to 79. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Upcountry

Today: Sunny. Highs around 58 at the visitor center to around 62 at the summit. Light winds.

Tonight: Mostly clear. Lows 38 to 49. Light winds.

Tuesday: Mostly sunny with isolated showers. Highs around 57 at the visitor center to around 61 at the summit. Light winds. Chance of rain 20 percent.

East Maui

Today: Sunny. Highs 73 to 78 near the shore to around 62 near 5000 feet. Northeast winds up to 15 mph.

Tonight: Partly cloudy with isolated showers. Lows around 64 near the shore to around 45 near 5000 feet. Northeast winds up to 10 mph shifting to the southeast after midnight. Chance of rain 20 percent.

Tuesday: Partly sunny with scattered showers. Highs around 75 near the shore to around 60 near 5000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Lanai City

Today: Sunny and breezy. Highs 67 to 75. Northeast winds 15 to 20 mph.

Tonight: Mostly clear. Lows around 60. Northeast winds 10 to 15 mph.

Tuesday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 67 to 74. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Kaunakakai

Today: Sunny. Highs 65 to 80. Northeast winds 10 to 15 mph.

Tonight: Mostly clear in the evening, then mostly cloudy with isolated showers after midnight. Lows 51 to 67. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs 63 to 79. Northeast winds up to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Dry conditions will continue the next few days. Light north to northeasterly trade flow within this dry environment will allow for seasonable cool mornings and comfortably warm afternoons through the middle of the week. Light showers will mainly focus on windward exposures and along mauka slopes. An upper level trough passage Tuesday will increase late Monday into Tuesday morning's rain chances. A weak frontal passage to the north on Thursday may briefly disrupt trades and provide a minor uptick in shower activity. Easterly trade wind behavior will return by Friday and persist into early next week. A more wet pattern is forecast next week.

Discussion

A very pleasant start to the new week under partially cloudy skies with generally light northerly winds or variable breezes. Winds are gradually veering back to trade flow through the day. Overnight IR satellite imagery depicts stable bands of shallow stratocumulus moving across the island chain from the north. Surface high pressure northwest of the state will be advancing east and passing north of the state the next couple of days. This high will drive gentle trade winds through Thursday. Ridging moving across from the west, in tandem with limited available moisture, will keep leeward and lower elevation skies mainly clear. Thicker cloud cover and light precipitation will be confined to the better-exposed windward areas and mauka slopes. The lack of any large scale forcing within gentle trades will allow for more wind-sheltered local diurnal wind behavior. While daytime sea breezes will assist in the build up of leeward slope cumulus and subsequent isolated showers, nocturnal drainage winds will clear out evening skies.
A shallow frontal boundary and associated upper trough will pass north of the state from late tonight through Tuesday. Slight to low end moderate probabilities for light showers over better- exposed windward communities and higher elevation. Shortwave energy diving into a larger scale trough far north of the state Thursday will subtly lower heights across the islands. A surface reflection of a weak front may graze the state to the north. This will briefly disrupt east trade flow Thursday. Moisture depth will likely be too shallow for this weak front to generate much precipitation in its eastern passage. The end story is that there will be no significant weather to close out the week from the passage of this weak upper trough Thursday night. High pressure west of the island chain will pass over Friday and, once northeast of the state, trade flow will return next weekend. After this relatively drier week, a more wet pattern may begin to take shape early next week. Deeper mid layer moisture pooling up east of broad upstream North Pacific troughing may increase regional rain chances. More active and frequent rain will likely focus along windward Big Island and Maui County next Monday and Tuesday within strengthening east trades.

Aviation

A mostly dry and stable airmass over the islands will continue today. North to northeast winds will continue which will lead to some cloud development over windward and north facing slopes. VFR conditions are expected to prevail with limited rainfall. An uptick in shower activity is possible late this afternoon/evening around Kauai, and over Oahu and Maui County tonight. No AIRMETs are in effect, and none are expected today.

Marine

Moderate to locally fresh north-northeast winds are expected today as a weak high pressure northwest of the state slowly tracks eastward. Winds will veer to the east and weaken Tuesday night through Thursday. By Friday through the end of the week, high pressure to the far northeast will build bringing back moderate to locally fresh trade winds. Trade winds remain just under Small Craft Advisory through the forecast period for the windier waters and channels around Maui County and the Big Island.
A combo of a moderate to large medium period north-northeast swell that has begun to rise at the nearshore buoys and a small to moderate, medium period northwest swell expected to slowly build this afternoon will produce moderate to large surf along north facing shores through Tuesday. Latest observations are showing the north- northeast swell filling in and expected to peak this morning before gradually declining through the middle of the week. A High Surf Advisory has been issued for all exposed north facing shores through tonight. A Small Craft Advisory has also been issued for seas greater than 10 feet in exposed waters and channels across the state. Also, a Marine Weather Statement has been issued for Maui County windward waters and Big Island windward waters in regards to north facing harbors such as Kahului and Hilo through tonight because of the north-northeast swell.
Surf along east facing shores will remain small except for shorelines exposed to the north- northeast swell through Wednesday. Surf along south facing shores will remain tiny through the forecast period with mainly background energy.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 AM HST Tuesday for Niihau, Oahu North Shore, Olomana, Maui Windward West, Kauai North, Kauai East, Koolau Windward, Molokai Windward, Molokai North, Maui Central Valley North, Windward Haleakala, Big Island East, Big Island North.
Small Craft Advisory until 6 AM HST Tuesday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Kaiwi Channel, Maui County Windward Waters, Alenuihaha Channel, Big Island Windward Waters.

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Data Courtesy of NOAA.gov