Hilo

Today: Partly sunny. Occasional light showers in the morning, then scattered showers in the afternoon. Highs 77 to 83 near the shore to 62 to 71 at 4000 feet. North winds up to 15 mph. Chance of rain 90 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. Northeast winds up to 10 mph. Chance of rain 90 percent.

Friday: Cloudy with showers likely in the morning, then partly sunny with scattered showers in the afternoon. Highs around 81 near the shore to 64 to 72 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Kona

Today: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 86 near the shore to around 68 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 72 near the shore to around 57 near 5000 feet. Light winds. Chance of rain 50 percent.

Friday: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 86 near the shore to around 70 near 5000 feet. Light winds. Chance of rain 40 percent.

Waimea

Today: Partly sunny. Breezy. Light showers likely in the morning, then scattered showers in the afternoon. Highs 65 to 87. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 70 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 64 to 70 near the shore to 56 to 64 near 3000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Friday: Partly sunny with scattered showers. Highs 68 to 87. East winds 10 to 15 mph. Chance of rain 50 percent.

Kohala

Today: Partly sunny. Breezy. Light showers likely in the morning, then scattered showers in the afternoon. Highs 65 to 87. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 70 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 64 to 70 near the shore to 56 to 64 near 3000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Friday: Partly sunny with scattered showers. Highs 68 to 87. East winds 10 to 15 mph. Chance of rain 50 percent.

South Big Island

Today: Mostly sunny. Breezy. 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.

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 73 near the shore to around 54 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Friday: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs around 86 near the shore to around 69 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Puna

Today: Partly sunny. Occasional light showers in the morning, then scattered showers in the afternoon. Highs 77 to 83 near the shore to 62 to 71 at 4000 feet. North winds up to 15 mph. Chance of rain 90 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. Northeast winds up to 10 mph. Chance of rain 90 percent.

Friday: Cloudy with showers likely in the morning, then partly sunny with scattered showers in the afternoon. Highs around 81 near the shore to 64 to 72 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Waikoloa

Today: Breezy. Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 82 to 89 near the shore to 68 to 73 above 4000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 73 near the shore to 52 to 58 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Friday: Sunny in the morning then becoming partly sunny. Highs 82 to 89 near the shore to 66 to 73 above 4000 feet. Northeast winds up to 10 mph.

Detailed Forecast

Synopsis

A large area of high pressure will remain anchored well north of the islands through the remainder of the work week, before slowly beginning to drift eastward this weekend. This pattern will maintain moderate to breezy easterly trade winds across the state through the weekend. Moist trade wind flow will enhance showers across the islands this morning, while varying amounts of moisture drifting across the region will maintain chances for showers across mainly windward and mauka sections through the weekend.

Discussion

The latest radar data and surface observations continue to show showers passing across the western and central islands this morning, particularly across windward zones and in channels between islands, as a band of low level moisture continues to stream into the region from the east. Rainfall reports through this morning shows highest rainfall amounts over portions of Kauai and Oahu, with some reports nearing one third of an inch. Much weaker and more sporadic radar returns have been noted over Maui County and the Big Island through early this morning, while isolated showers continue to drift across some leeward zones. The latest model guidance and satellite based layer precipitable water imagery, suggests the low level moisture which has been flowing across the islands this morning, will continue through this afternoon. This pattern will maintain showers along favored windward zones, with low level streamline flow supporting the greatest areal coverage of showers to linger across Molokai, Oahu and Kauai into Friday.
Otherwise, high pressure well north of the state will maintain breezy to locally strong trades through the weekend, and lingering into early next week. This pattern will continue to generate showers across mainly windward zones, however a slightly drier trend expected Sunday, will help reduced the areal coverage and intensity of showers into early next week.
Some tropical moisture may increase across the islands, especially windward Big Island and east Maui Wednesday, in response to dissipating remnants of TC Bonnie. The latest GFS and ECMWF models remain in reasonably good agreement with the overall trend of this diminishing feature, however there remains uncertainty on timing and track of this feature, though have continued with higher chances for showers developing next week. Stayed tuned to future forecasts and updates regarding next weeks rainfall potential.

Aviation

A high pressure system far north of the Hawaiian Islands will keep moderate to breezy trade winds in the forecast into the first half of next week. Bands of clouds from a dissipated front are moving through the islands this morning enhancing showers as it drifts into the islands on the trade winds. The highest chances for rainfall are forecast over windward and mountain areas with some of the stronger showers reaching leeward airfields mainly in the early morning hours. Periods of MVFR conditions should be expected over windward airfields through the morning hours with mostly VFR conditions forecast elsewhere.
AIRMET Sierra in effect today for low clouds and showers moving into the windward and mountain sections of each island producing periods of mountain obscurations. Mountain obscurations will decrease in coverage later this morning to afternoon. AIRMET Tango remains in effect for low level mechanical turbulence downwind island mountains due to breezy trade winds. This AIRMET will likely continue through Friday.

Marine

Strong high pressure north of the islands will keep moderate to locally strong trades in place through Friday. The trades will then ramp back up to fresh to strong levels over the weekend through early next week. A Small Craft Advisory (SCA) is now in effect for the windier zones around Maui and the Big Island through 6 PM Monday. The SCA may need to be expanded to include additional areas over the weekend.
No significant swells are expected over the next several days. East shore surf will remain slightly below normal through Friday, before rising back up to near seasonal levels over the weekend through the middle of next week as the trades strengthen over and upstream of the island chain. South shore surf will remain small through Saturday, before a long-period south swell arrives and boosts surf to near or slightly above the summertime average Sunday through the middle of next week. East Pacific Hurricane Bonnie may send a small, long-period east swell our way early next week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Monday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov