Hilo

Tonight: Haze in the evening. Partly cloudy with scattered showers. Lows 59 to 66 near the shore to 46 to 53 at 4000 feet. Southeast winds up to 10 mph shifting to the southwest after midnight. Chance of rain 30 percent.

Saturday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Haze in the afternoon. Highs around 80 near the shore to 65 to 70 at 4000 feet. South winds up to 10 mph shifting to the southeast in the afternoon. Chance of rain 30 percent.

Saturday Night: Haze in the evening. Partly cloudy with scattered showers. Lows 59 to 67 near the shore to 47 to 54 at 4000 feet. Light winds. Chance of rain 40 percent.

Kona

Tonight: Mostly cloudy in the evening then becoming mostly clear. Isolated showers. Haze. Lows around 69 near the shore to 42 to 49 near 5000 feet. Light winds. Chance of rain 20 percent.

Saturday: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Haze through the day. Highs around 83 near the shore to around 66 near 5000 feet. Light winds. Chance of rain 30 percent.

Saturday Night: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Haze. Lows around 69 near the shore to 42 to 49 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Partly cloudy with isolated showers. Haze. Lows 59 to 68 near the shore to 50 to 58 near 3000 feet. South winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Haze. Highs around 78 near the shore to 70 to 76 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Saturday Night: Haze in the evening. Partly cloudy with isolated showers. Lows 59 to 68 near the shore to 51 to 58 near 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Kohala

Tonight: Partly cloudy with isolated showers. Haze. Lows 59 to 68 near the shore to 50 to 58 near 3000 feet. South winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Haze. Highs around 78 near the shore to 70 to 76 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Saturday Night: Haze in the evening. Partly cloudy with isolated showers. Lows 59 to 68 near the shore to 51 to 58 near 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

South Big Island

Tonight: Mostly cloudy in the evening then becoming mostly clear. Isolated showers. Haze. Lows around 70 near the shore to around 48 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Saturday: Breezy. Sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Haze through the day. Highs around 83 near the shore to around 67 near 5000 feet. East winds up to 20 mph. Chance of rain 30 percent.

Saturday Night: Mostly cloudy in the evening then becoming mostly clear. Isolated showers. Haze. Lows around 70 near the shore to around 49 near 5000 feet. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Puna

Tonight: Haze in the evening. Partly cloudy with scattered showers. Lows 59 to 66 near the shore to 46 to 53 at 4000 feet. Southeast winds up to 10 mph shifting to the southwest after midnight. Chance of rain 30 percent.

Saturday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Haze in the afternoon. Highs around 80 near the shore to 65 to 70 at 4000 feet. South winds up to 10 mph shifting to the southeast in the afternoon. Chance of rain 30 percent.

Saturday Night: Haze in the evening. Partly cloudy with scattered showers. Lows 59 to 67 near the shore to 47 to 54 at 4000 feet. Light winds. Chance of rain 40 percent.

Waikoloa

Tonight: Partly cloudy with isolated showers. Haze. Lows 67 to 72 near the shore to 45 to 52 above 4000 feet. Light winds. Chance of rain 20 percent.

Saturday: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Haze through the day. Highs around 83 near the shore to 63 to 70 above 4000 feet. East winds up to 10 mph shifting to the northwest in the afternoon. Chance of rain 20 percent.

Saturday Night: Partly cloudy with isolated showers. Haze. Lows around 69 near the shore to 46 to 52 above 4000 feet. Light winds. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Light to locally moderate trade winds and mostly dry conditions will prevail through early next week, with a few showers possible along windward slopes and coasts at night and over the island interiors each afternoon. A series of cold fronts will approach from the northwest next week, bringing an increase in showers, particularly over the western end of the state around the middle of the week and again towards the end of the work week.

Discussion

This afternoon's radar and satellite imagery show clouds and a few showers moving into windward areas as a plume of moisture rides in on the ESE trades, as well as forming over leeward and interior areas with the localized sea breezes. Only light rainfall amounts are expected with these brief passing showers due to limited available moisture and increasing stability as mid-level ridging builds in from the west.
A progressive pattern to our north will bring a series of fronts to our doorstep over the next several days, periodically disrupting the trades and bringing an increase in showers to the western end of the state. Between each front, the surface ridge to the northeast of the state will try to reestablish itself, but will have a hard time doing so as each front will be followed closely by its successor. In this pattern, the main forecast focus will continue to revolve around wind trends and rain chances.
The first of these fronts will approach tomorrow into Sunday, then dissipate northwest of the state. As this boundary approaches, it will act to weaken the local pressure gradient and maintain light winds across the region through early next week. Since the moisture associated with this frontal boundary isn't expected to reach the state, rain chances will be driven by the light ESE trades that will allow for clouds and showers to generally focus over windward and mauka areas overnight, then transition to focus over leeward and interior areas with sea breeze development each afternoon.
The second front will approach early to mid week next week and may increase rain chances over the western end of the state Tuesday night into Wednesday as the frontal boundary dissipates near Kauai. However, model guidance shows both the boundary and its moisture field mostly dissipating before reaching the state, so not expecting much of an uptick in shower activity with this front either.
Then ahead of the third front, winds will turn southerly across the region Wednesday and Thursday, allowing the boundary layer to moisten up and inversion heights to rise, bringing a slight increase in shower activity, particularly over the western end of the state. The third front looks to approach towards the end of the work week, potentially bringing another, slightly more significant bump in rain chances for the western end of the state Thursday night into Friday.

Aviation

A surface ridge just north of the islands gradually shift southward, which will bring light and variable winds across many areas of the state tonight into Saturday. Afternoon clouds today should decrease this evening and tonight as land breezes develop across many areas. Sea breezes developing during the day on Saturday will bring an increase of clouds and a few showers during the afternoon on Saturday. Brief MVFR ceilings will be possible with any shower development during the afternoon.
No AIRMETs are expected.

Marine

Strong high pressure remains over the northeastern Pacific, with a ridge extending southwest to just north of Hawaii. The ridge will shift south this evening, causing low-level winds to weaken and shift more southeasterly by late evening, then become light and variable over the western end of the island chain late tonight into Saturday. Light to moderate easterly trade wind flow will return Sunday into next week as high pressure rebuilds north of the state.
The current west-northwest swell will continue its gradual decline through tonight. The next significant northwest swell is due late Saturday into early next week, with peak surf heights nearing and potentially reaching warning levels along north and west facing shores Saturday night and Sunday. Will likely need a High Surf Advisory or Warning issued sometime Saturday. Another similarly- sized northwest swell is expected to build in Tuesday night and linger through Wednesday.
Small surf is expected along east facing shores over the next week as trade winds remain light. Surf along south facing shores should see a small boost through Saturday as a small south swell fills in.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov