Hilo

Tonight: Cloudy with scattered showers. Lows 64 to 71 near the shore to 53 to 58 at 4000 feet. Light winds becoming northwest up to 10 mph after midnight. Chance of rain 50 percent.

Tuesday: Cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 79 to 85 near the shore to around 65 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy with scattered showers. Lows 64 to 71 near the shore to 52 to 58 at 4000 feet. Light winds. Chance of rain 50 percent.

Kona

Tonight: Cloudy with isolated showers. Lows around 73 near the shore to 50 to 55 near 5000 feet. Light winds. Chance of rain 20 percent.

Tuesday: Cloudy with isolated showers. Highs 82 to 87 near the shore to around 66 near 5000 feet. Light winds. Chance of rain 20 percent.

Tuesday Night: Mostly cloudy with isolated showers. Lows around 73 near the shore to around 52 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Cloudy with scattered showers. Lows 63 to 72 near the shore to 56 to 63 near 3000 feet. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 40 percent.

Tuesday: Mostly cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 80 near the shore to 69 to 78 near 3000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Tuesday Night: Mostly cloudy with isolated showers. Lows 63 to 73 near the shore to 56 to 63 near 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Kohala

Tonight: Cloudy with scattered showers. Lows 63 to 72 near the shore to 56 to 63 near 3000 feet. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 40 percent.

Tuesday: Mostly cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 80 near the shore to 69 to 78 near 3000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Tuesday Night: Mostly cloudy with isolated showers. Lows 63 to 73 near the shore to 56 to 63 near 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

South Big Island

Tonight: Cloudy. Isolated showers in the evening. Lows around 74 near the shore to around 56 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tuesday: Cloudy. Isolated showers in the afternoon. Highs around 85 near the shore to around 63 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tuesday Night: Cloudy. Lows around 74 near the shore to around 55 near 5000 feet. Northeast winds up to 15 mph.

Puna

Tonight: Cloudy with scattered showers. Lows 64 to 71 near the shore to 53 to 58 at 4000 feet. Light winds becoming northwest up to 10 mph after midnight. Chance of rain 50 percent.

Tuesday: Cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 79 to 85 near the shore to around 65 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy with scattered showers. Lows 64 to 71 near the shore to 52 to 58 at 4000 feet. Light winds. Chance of rain 50 percent.

Waikoloa

Tonight: Cloudy. Lows around 74 near the shore to 52 to 57 above 4000 feet. Southeast winds up to 15 mph.

Tuesday: Mostly cloudy. Highs around 86 near the shore to 64 to 71 above 4000 feet. North winds up to 15 mph.

Tuesday Night: Cloudy. Lows around 74 near the shore to around 54 above 4000 feet. East winds up to 10 mph.

Detailed Forecast

Synopsis

Moderate trade winds will continue this week. An upper level trough will help bring increased instability to the western end of the state, enhancing the chance for heavier showers into Wednesday. Possible unsettled weather this weekend.

Discussion

Water vapor imagery shows an upper trough across the western end of the state this afternoon. The trough is responsible for bringing up mid and high clouds that have been over the area this past weekend. At the surface, moderate trade winds are driven by highs far northeast and north northwest. A cold front far to the north separates the two highs.
Visible satellite and radar imagery shows a swath of mid and high clouds across Oahu and Maui County. Rain amounts have been minimal, but aside of Kauai this afternoon, mostly cloudy skies prevail. The upper trough will linger near Kauai through Wednesday before weakening and broadening across the state. A few enhanced showers are expected near Kauai through Wednesday, with a few thunderstorms possible north of this area. Models also indicate enough instability developing in the trough that has moved over the Big Island over the Big Island to warrant a mention of thunderstorms Wednesday afternoon.
A cold front will slowly approach during the second half of the week with a gradual trend down in winds. A deep low pressure system will dig southward towards the Hawaii forming a surface low north of the state. Winds will taper off as this low nears, but long range models vary on where the low sets up. For now it looks like a wet and unsettled weather this weekend with flash flood and thunderstorms possible.

Aviation

Moderate to breezy trade winds will gradually ease through the week as a front far to the north weakens the surface high pressure. Showers from low clouds on the trade winds will mostly focus over windward and mountain areas through this afternoon. Expect an increase in showers along windward and mauka regions tonight as a band of moisture associated with the front moves south near the western end of the state. Low ceilings and MVFR conds are possible in any heavier showers, otherwise VFR should prevail. In addition, an upper level trough will linger across the state into Tuesday. This should continue drawing up mid and upper level clouds and a few light showers from the south through the forecast period, as well as provide a slight chance of thunderstorms over the waters west of Kauai.
AIRMET Tango is in effect for tempo moderate upper level turbulence between FL250 and FL380. This should continue through today.

Marine

High pressure far northeast of the Hawaiian coastal waters will continue to weaken as a front stalls north of the area and weakens through midweek. A weak ridge will nose into the northern offshore waters later this week before another front approaches the area. Expect moderate to locally breezy trades through the week, with an uptick in winds likely this weekend as a front approaches the state from the northwest.
Surf along north facing shores will see a slight decline tonight into Tuesday as a short to medium period north-northwest (330-340 degree) swell slowly fades. An incoming moderate short-period north-northwest (330-350 degree) swell will produce another bump in north shore surf Tuesday night into Wednesday. However, the low that generated Wednesday's swell was rather compact and fast- moving so there remains some uncertainty regarding potential surf heights. Model guidance for north swells have trended towards a low bias so surf heights may come in higher then predicted. Stay tuned for more details. A new north-northwest swell will bring near advisory level surf over the weekend along exposed north and west facing shores.
Surf along east facing shores will remain small to moderate as the trades ease. Although, shorelines exposed to the north swell on Wednesday may see an increase in surf. South facing shores will continue to see mainly small background swells through the week.

Fire weather

Low-level moisture is expected to be high enough this week to keep RH values above critical levels. Trade winds will still be present, but weaker, in the coming days. Temperature inversion heights will range from 6,500 to 7,500 ft through tomorrow.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov