Hilo

Tonight: Occasional showers. Lows 60 to 69 near the shore to 49 to 56 at 4000 feet. Southeast winds up to 10 mph. Chance of rain near 100 percent.

Friday: Occasional showers in the morning, then scattered showers in the afternoon. Haze in the afternoon. Highs 77 to 82 near the shore to around 65 at 4000 feet. East winds up to 10 mph. Chance of rain near 100 percent.

Friday Night: Mostly cloudy. Occasional showers in the evening, then scattered showers after midnight. Lows 60 to 69 near the shore to 49 to 55 at 4000 feet. East winds up to 10 mph. Chance of rain 90 percent.

Kona

Tonight: Mostly clear. Haze. Lows around 71 near the shore to 46 to 52 near 5000 feet. Northeast winds up to 10 mph.

Friday: Mostly sunny. Haze. Highs 83 to 88 near the shore to around 66 near 5000 feet. North winds up to 10 mph in the morning becoming light.

Friday Night: Partly cloudy. Haze. Lows 69 to 74 near the shore to 47 to 52 near 5000 feet. Light winds.

Waimea

Tonight: Mostly clear with scattered showers. Lows 61 to 70 near the shore to 53 to 61 near 3000 feet. Southeast winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 50 percent.

Friday: Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Haze in the afternoon. Highs around 79 near the shore to 68 to 78 near 3000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Friday Night: Mostly cloudy with scattered showers in the evening, then partly cloudy after midnight. Haze through the night. Lows 61 to 70 near the shore to 53 to 60 near 3000 feet. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 50 percent.

Kohala

Tonight: Mostly clear with scattered showers. Lows 61 to 70 near the shore to 53 to 61 near 3000 feet. Southeast winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 50 percent.

Friday: Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Haze in the afternoon. Highs around 79 near the shore to 68 to 78 near 3000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Friday Night: Mostly cloudy with scattered showers in the evening, then partly cloudy after midnight. Haze through the night. Lows 61 to 70 near the shore to 53 to 60 near 3000 feet. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 50 percent.

South Big Island

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Breezy and haze. Lows around 73 near the shore to around 53 near 5000 feet. East winds 15 to 20 mph.

Friday: Breezy. Partly sunny in the morning, then mostly sunny with isolated showers in the afternoon. Haze through the day. Highs around 85 near the shore to around 66 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Friday Night: Partly cloudy. Breezy. Isolated showers in the evening. Haze through the night. Lows around 73 near the shore to around 53 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Puna

Tonight: Occasional showers. Lows 60 to 69 near the shore to 49 to 56 at 4000 feet. Southeast winds up to 10 mph. Chance of rain near 100 percent.

Friday: Occasional showers in the morning, then scattered showers in the afternoon. Haze in the afternoon. Highs 77 to 82 near the shore to around 65 at 4000 feet. East winds up to 10 mph. Chance of rain near 100 percent.

Friday Night: Mostly cloudy. Occasional showers in the evening, then scattered showers after midnight. Lows 60 to 69 near the shore to 49 to 55 at 4000 feet. East winds up to 10 mph. Chance of rain 90 percent.

Waikoloa

Tonight: Mostly clear. Lows 69 to 74 near the shore to 48 to 53 above 4000 feet. Light winds.

Friday: Mostly sunny. Isolated showers in the afternoon. Haze in the afternoon. Highs around 85 near the shore to 65 to 71 above 4000 feet. Light winds. Gusts up to 25 mph. Chance of rain 20 percent.

Friday Night: Partly cloudy. Haze. Lows 69 to 74 near the shore to 48 to 54 above 4000 feet. Light winds.

Detailed Forecast

Synopsis

Breezy ESE winds will weaken and back to easterly during the weekend. Limited clouds and showers will focus windward and mauka during this time.

Discussion

Convergence and moisture pooling along a cold front supports ongoing convection west of Kauai. This convection will persist through today, then dissipate this evening into tonight as the supporting upper trough lifts to the north. This then allows moderate to breezy ESE winds to usher remaining frontal moisture west of the area leaving the islands mostly dry, including Kauai. The only sensible wx effect of the front locally will be increased cirrus gracing western skies. Given the observed inversion at Lihue this morning around 4.5kft, expect relatively little to no shower activity.
A batch of moisture embedded within the tropical easterlies is observed on visible imagery around 150W/18N. Modeling indicates this moisture advances toward the area within prevailing ESE low/mid level flow and focuses showers chiefly over favored slopes of the Big Island and Windward Haleakala on Maui tonight through Friday. This moisture may supply ESE flow with enough moisture to support a few showers across both windward and leeward portions of the smaller islands during this time, but no organized or heavy rainfall is anticipated.
Another punch of dry mid-level air brings reinforcing stability over the weekend as the Pacific Jet extends eastward leaving the islands in a region of large scale subsidence. Dry, moderate trades continue into next week.

Aviation

Strengthening winds out of the southeast will continue through Friday as high pressure builds across the area. VFR conditions prevail with only isolated mountain obscurations this afternoon. A few clouds and showers may impact windward and southeast Big Island overnight, but partly cloudy skies will continue across the rest of the state.
AIRMET Tango for tempo moderate leeward turbulence is expected to go into effect later tonight as the southeast winds pick up. No other AIRMETs are in effect or anticipated tonight.

Marine

A trough west of Kauai will gradually weaken and retrograde westward, away from the islands. Meanwhile, a ridge of surface high pressure building northeast of the state will allow for moderate to locally strong east or east southeast winds to persist through early Saturday. A Small Craft Advisory (SCA) remains in effect through 6 AM Saturday morning for most of the marine zones surrounding the Big Island and Maui County for strong winds, and the north and western zones around Kauai and Oahu have been added starting at 6 PM this evening for building seas.
A moderate, medium period northwest swell (320 degrees) is filling in across north and west facing shores of Kauai and Oahu this afternoon as seen at the Waimea buoy, bringing surf heights above High Surf Advisory (HSA) criteria. This swell is expected to peak tonight into early Friday, then ease into the weekend. A HSA is in effect for north and west facing shores of Oahu and Kauai this afternoon and will expand across north and west shores of Molokai and north shores of Maui this evening. This swell will hold through Friday, then gradually fade and veer to the north northwest through the remainder of the weekend and into early next week and bring below average surf for December for north and west facing shores.
East shore surf will gradually build and become choppy tonight through Friday as trade winds increase. Expect minimal background energy for south facing shores through much of the week.
Peak monthly tides combined with water levels that are running higher than predicted will likely lead to minor flooding along the shoreline and in low-lying coastal areas. Coastal flooding is possible around the daily peak tide, which will be during the early morning hours. This could also magnify effects of the high surf on coastal areas along north and west facing shores around the same time frame.

Fire weather

Critical fire weather conditions are not expected this week. Light winds will give way to mainly moderate east to southeast winds today, but winds will be below the critical fire weather threshold. The inversion morning sloped from around 4.5kft at Lihue to around 7.5kft at Hilo.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST Friday for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Kauai North.
High Surf Advisory until 6 PM HST Friday for Maui Windward West, Molokai Windward, Molokai North, Molokai West, Maui Central Valley North, Windward Haleakala.
Small Craft Advisory until 6 AM HST Saturday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Channel, Oahu Windward Waters, Kaiwi Channel.
Small Craft Advisory until 6 AM HST Saturday for Maui County Windward Waters, Pailolo Channel, Alenuihaha Channel, Big Island Windward Waters, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov