Photo Credit: Leosan Miguel

West Side

Today: Sunny, with a high near 87. Windy, with an east northeast wind around 25 mph, with gusts as high as 38 mph.

Tonight: Clear, with a low around 75. Windy, with an east northeast wind 17 to 25 mph, with gusts as high as 38 mph.

Monday: Sunny, with a high near 87. Windy, with an east northeast wind 21 to 24 mph, with gusts as high as 34 mph.

South Side

Today: Increasing clouds, with a high near 86. Calm wind becoming west 5 to 7 mph in the morning.

Tonight: Mostly clear, with a low around 71. Calm wind.

Monday: Mostly sunny, with a high near 86. Calm wind becoming northeast 5 to 9 mph in the afternoon.

North Shore

Today: Sunny, with a high near 85. Windy, with an east wind 23 to 29 mph, with gusts as high as 41 mph.

Tonight: Mostly clear, with a low around 72. Windy, with an east wind 21 to 25 mph, with gusts as high as 36 mph.

Monday: Sunny, with a high near 85. Windy, with an east wind 18 to 25 mph, with gusts as high as 36 mph.

Central Maui

Today: Sunny, with a high near 88. Windy, with an east northeast wind 18 to 26 mph, with gusts as high as 38 mph.

Tonight: Mostly clear, with a low around 72. Windy, with an east northeast wind 20 to 25 mph decreasing to 14 to 19 mph after midnight. Winds could gust as high as 36 mph.

Monday: Sunny, with a high near 88. Windy, with an east northeast wind 14 to 23 mph, with gusts as high as 32 mph.

Upcountry

Today: Sunny, with a high near 76. West southwest wind 5 to 8 mph.

Tonight: Mostly clear, with a low around 61. Southeast wind around 5 mph.

Monday: Sunny, with a high near 76. Light and variable wind becoming east northeast 5 to 9 mph in the afternoon.

East Maui

Today: Scattered showers. Partly sunny, with a high near 80. Breezy, with an east northeast wind 9 to 15 mph, with gusts as high as 21 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 71. East northeast wind 3 to 8 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Monday: Scattered showers. Partly sunny, with a high near 80. Breezy, with an east northeast wind 11 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Lanai City

Today: Increasing clouds, with a high near 80. Windy, with an east northeast wind 20 to 25 mph, with gusts as high as 41 mph.

Tonight: Mostly clear, with a low around 66. Windy, with an east northeast wind 16 to 23 mph, with gusts as high as 38 mph.

Monday: Increasing clouds, with a high near 80. Windy, with an east northeast wind 20 to 25 mph, with gusts as high as 36 mph.

Kaunakakai

Today: Sunny, with a high near 84. Breezy, with an east northeast wind around 18 mph, with gusts as high as 25 mph.

Tonight: Mostly clear, with a low around 71. Breezy, with an east northeast wind around 18 mph, with gusts as high as 25 mph.

Monday: Sunny, with a high near 84. Breezy, with an east northeast wind 18 to 21 mph, with gusts as high as 29 mph.

Detailed Forecast

Synopsis

Locally strong and gusty trade winds along with stable and rather dry conditions will persist today. Winds will gradually ease Monday through Wednesday as the high pressure far northeast of the state weakens. Rather dry conditions will prevail into Tuesday with an uptick in mainly windward showers expected by Wednesday.

Discussion

A rather dry, stable, and gusty trade wind flow remains in place. A 1032 mb high parked nearly 1500 miles northeast of the state is driving the trades, and a ridge aloft overhead is producing very stable conditions with a strong low level inversion. As a result, scant rainfall was observed on windward slopes yesterday and overnight, and aside from typical afternoon and evening showers on the South Kona slopes, leeward areas have been very dry, including sections of interior and leeward Big Island where a large wildfire continues to burn.
Trades will increase slightly today as high pressure to the northeast strengthens and edges slightly closer, and a firm ridge overhead will maintain stable conditions with limited rainfall. Due to the expected increase in trade winds, a Wind Advisory is in effect for portions of Maui, Lanai, and the Big Island, including the area where the large wildfire is burning. Another dry day is in store with meager windward rainfall and sunny skies over most leeward areas. Trades will gradually ease Monday and Tuesday as the high to the northeast weakens, though dry and stable conditions will likely hold.
Typical summer trade wind weather is expected by Wednesday. High pressure will remain to the north of the state, but trades will drop into the moderate to locally breezy range. A weakness in the ridge aloft should allow the inversion to raise slightly, and the GFS and ECMWF are hinting at an increase in low level moisture that would translate into more windward showers.

Aviation

Stable conditions will support prevailing VFR through the forecast period. Locally strong trades will focus occasional light showers over windward slopes, mainly overnight, but any MVFR due to clouds or shower activity will be fleeting. Low-level wind shear characteristic of strong trades will be possible in favored locations, namely around Maui and particularly in the vicinity of PHOG. Finally, areas of low visibility are still possible over sections of Leeward Big Island and adjacent waters due to wildfire smoke.
AIRMET Tango for lee turbulence below 8kft will remain in effect through the period.

Marine

Surface high pressure building far north-northeast of the state will produce strong trade winds and elevated, rough seas today. A Gale Warning has been issued for the typically windier waters adjacent to the islands of Maui County and the Big Island through this afternoon. A Small Craft Advisory (SCA) is also in effect for the remaining Hawaiian waters today. The latest forecast shows the trade winds weakening slightly by this evening. Expect locally strong trade winds to continue for the typically windier waters, so the SCA will likely be posted for these waters starting tonight, and continuing through mid-week. Note that some additional waters may require a SCA tonight.
Recent observations from the nearshore buoys at Pauwela and Kaneohe Bay show wave heights of around 6 feet with wave periods near 8 seconds, which likely reflects the strengthening trade winds. Expect the rough, slightly elevated surf to persist along east facing shores into Tuesday. Surf heights may decrease to near the summertime average along east facing shores by mid-week as the trade winds weaken slightly.
Small south and south-southeast swells will maintain small surf along south facing shores today. There will mainly be residual south-southeast swell energy keeping below normal summertime surf along south facing shores from Monday through mid-week. The forecast guidance shows a small southwest swell arriving next Friday, which may provide a small boost in surf heights along exposed south facing shores heading into next weekend.
The nearshore buoys at Hanalei and Barbers Point continue to show tiny west-northwest swell energy, which was generated by recent west Pacific tropical cyclone activity. This may produce a slight bump in surf along exposed west facing shores of Kauai, and possibly Oahu, today. Otherwise, expect nearly flat conditions along most north and west facing shores this week.

Fire weather

Near critical fire weather conditions will persist into Monday due to strong and gusty trade winds and a rather dry and stable atmosphere. The Keetch Byram Drought Index at Honolulu will be just shy of the critical 600 mark during the next couple of days, but winds and daytime relative humidity will be at or very close to critical thresholds today. A slight drop in winds is expected on Monday and Tuesday, but dry leeward conditions will hold.

HFO Watches/Warnings/Advisories

Wind Advisory from 6 AM this morning to 6 PM HST this evening for Lanai Mauka, Maui Leeward West, Kohala, Big Island Interior, Lanai Windward, Lanai Leeward, Maui Central Valley North, Maui Central Valley South, Big Island South, Big Island Southeast.
Gale Warning until 6 PM HST this evening for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 PM HST this evening 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.

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Data Courtesy of NOAA.gov