Hilo

Today: Cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 80 to 85 near the shore to 65 to 73 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Tonight: Cloudy. Showers likely in the evening, then occasional showers after midnight. Lows 64 to 72 near the shore to around 57 at 4000 feet. North winds up to 15 mph. Chance of rain 80 percent.

Sunday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 81 to 86 near the shore to 65 to 73 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Kona

Today: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 82 to 89 near the shore to around 70 near 5000 feet. West winds up to 10 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows around 73 near the shore to 51 to 56 near 5000 feet. Light winds. Chance of rain 20 percent.

Sunday: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 82 to 89 near the shore to around 69 near 5000 feet. Light winds. Chance of rain 40 percent.

Waimea

Today: Breezy. Mostly cloudy with scattered showers. Highs 68 to 89. East winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 63 to 69 near the shore to 54 to 63 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs 67 to 89. East winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 50 percent.

Kohala

Today: Breezy. Mostly cloudy with scattered showers. Highs 68 to 89. East winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 63 to 69 near the shore to 54 to 63 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs 67 to 89. East winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 50 percent.

South Big Island

Today: Breezy. Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 85 near the shore to around 69 near 5000 feet. East winds up to 25 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening. Lows around 73 near the shore to around 53 near 5000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Sunday: Breezy. Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 86 near the shore to around 68 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Puna

Today: Cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 80 to 85 near the shore to 65 to 73 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Tonight: Cloudy. Showers likely in the evening, then occasional showers after midnight. Lows 64 to 72 near the shore to around 57 at 4000 feet. North winds up to 15 mph. Chance of rain 80 percent.

Sunday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 81 to 86 near the shore to 65 to 73 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Waikoloa

Today: Sunny in the morning then becoming partly sunny. Breezy. Highs 81 to 90 near the shore to 68 to 75 above 4000 feet. Northeast winds up to 25 mph.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening. Lows around 73 near the shore to 50 to 57 above 4000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Sunday: Sunny in the morning then becoming partly sunny. Highs 81 to 89 near the shore to 67 to 75 above 4000 feet. Northeast winds up to 15 mph.

Detailed Forecast

Synopsis

A weak upper trough drifting westward across the state, will enhance showers over the islands into this afternoon. Otherwise, moderate to locally breezy trades will generate a typical trade wind weather pattern through Sunday, with showers occasionally reaching leeward areas. Drier and more stable trade wind flow developing next week, will maintain showers across windward and mauka areas. Trades briefly weakening to begin the workweek, will allow for afternoon sea breeze showers across leeward areas through Tuesday. Trades will then restrengthen over the islands Wednesday through the end of the week.

Discussion

Radar trends continue to show showers drifting across the islands this morning, as trades have strengthened across the region. The showers early this morning have increased some since Friday evening, expanding into leeward marine waters of the state. Additionally, showers still remain focused along windward areas with the greatest concentration of showers over the smaller islands and Kauai, in an area of surface based streamline convergence. CIMSS satellite based data, shows the narrow band of increased layered precipitable water values (around 1.75 inches), which was moving toward windward zones Friday evening, now pushing across the islands and moving westward over leeward marine areas.
The weakly organized upper level trough will continue to slowly maneuver westward across the islands through today, before becoming anchored over the western end of the state Sunday. The upper trough has enhanced moisture depth and maintained elevated inversion heights (around 10k ft HLI, around 13k ft HTO 00z soundings) across the islands. The increased moisture and inversion heights will enhance shower activity across most islands through this afternoon. Showers will begin to decrease early Sunday as much drier and more stable conditions move in across the state (CIMSS based data, precipitable water values dropping to under 1.25 inches).
Lowering inversion heights, drier air and more stable conditions are expected to filter in across the region to begin the upcoming workweek, as the upper trough exits slowly west. The lingering trades next week, will maintain a typical trade wind weather pattern, focusing most of the showers and clouds to windward areas. Trade winds will weaken Monday and Tuesday, allowing the return of afternoon sea breeze clouds and showers across some interior sheltered leeward areas. Trades will then restrengthen Wednesday and Thursday, reestablishing the typical trade wind showers across mainly windward areas. Showers will be limited to end the workweek, as an upper ridge builds north of the state, further supporting a dry and stable airmass across this islands.

Aviation

Breezy easterly trade winds have returned and will persist through much of the 24-hr forecast period, with clouds and showers favoring windward and mauka locations. As a result, AIRMET Tango for low-level turbulence downwind of the terrain of all islands is now in effect. Although VFR conditions will prevail for most areas, periods of MVFR CIGS/VSBYS in and around passing showers are expected through the morning hours.
AIRMET Sierra for mountain obscuration is currently in effect for windward sections of Oahu and Kauai, which may persist through the early morning hours.

Marine

A surface high to the distant NNE has a ridge that extends to an area several hundred nm N of Kauai, supporting moderate to locally strong trade winds. A Small Craft Advisory (SCA) remains in place for the windier zones around Maui and the Big Island through tonight. The high will drift W with little change through tonight, then gradually weaken Sunday before more decided weakening occurs on Monday and Tuesday as a front moves in from the N. In response, trade wind speeds are expected to peak today, then gradually diminish into early next week, becoming gentle to moderate Monday and Tuesday. High pressure building far N of the area will likely lead to increasing trade wind speeds by midweek.
No significant swells are expected, and surf will be small along all shores for the foreseeable future.

Fire weather

An area of increased moisture and showers will push across the islands early this morning, in advance of much drier air drifting into the islands from the east. The drier airmass will combine with strengthening trades to around 20 mph, to enhance fire weather concerns for some leeward areas into this evening. The lowest relative humidity values are forecast to fall to around 40 percent today, which is about 5 percent lower than Friday. Humidity values are expected to remain low again on Sunday, however the latest trends continue to support lighter wind flow across these drier leeward areas on Sunday, reducing the critical fire weather threat.

HFO Watches/Warnings/Advisories

Red Flag Warning from 11 AM this morning to 6 PM HST this evening for Kauai Leeward, Oahu South Shore, Waianae Coast, Oahu North Shore, Olomana, Central Oahu, Waianae Mountains, Molokai Leeward, Maui Leeward West, Maui Central Valley, Leeward Haleakala, Kona, South Big Island, Kohala.
Small Craft Advisory until 6 AM HST Sunday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov