Photo Credit: Tyler Rooke

West Side

Today: Mostly sunny. Isolated showers in the afternoon. Highs 77 to 83. Light winds becoming northwest up to 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy after midnight. Lows 60 to 66. Light winds. Chance of rain 20 percent.

Monday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 77 to 83. Light winds becoming northwest up to 10 mph in the afternoon. Chance of rain 20 percent.

South Side

Today: Sunny. Highs around 83. Light winds.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Lows around 61. Light winds.

Monday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 83. Light winds becoming west up to 10 mph in the afternoon. Chance of rain 20 percent.

North Shore

Today: Mostly sunny with isolated showers. Highs 75 to 80 near the shore to around 63 near 5000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 58 to 64 near the shore to around 48 near 5000 feet. Southeast winds up to 10 mph in the evening becoming light. Chance of rain 30 percent.

Monday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 75 to 80 near the shore to around 62 near 5000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Central Maui

Today: Sunny. Highs 79 to 84. Northeast winds up to 10 mph.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Lows 59 to 64. Northeast winds up to 10 mph in the evening becoming light.

Monday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 79 to 84. Light winds becoming north up to 10 mph in the afternoon. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 59 at the visitor center to around 55 at the summit. Light winds. Chance of rain 30 percent.

Tonight: Mostly cloudy with isolated showers. Lows around 44 at the visitor center to around 40 at the summit. Light winds becoming northwest up to 10 mph after midnight. Chance of rain 20 percent.

Monday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 57 at the visitor center to around 53 at the summit. Northwest winds up to 10 mph. Chance of rain 40 percent.

East Maui

Today: Mostly sunny with isolated showers. Highs 75 to 80 near the shore to around 63 near 5000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 58 to 64 near the shore to around 48 near 5000 feet. Southeast winds up to 10 mph in the evening becoming light. Chance of rain 30 percent.

Monday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 75 to 80 near the shore to around 62 near 5000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Lanai City

Today: Mostly sunny. Isolated showers in the afternoon. Highs 73 to 80. Light winds. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows around 61. Light winds. Chance of rain 20 percent.

Monday: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 73 to 80. Light winds. Chance of rain 40 percent.

Kaunakakai

Today: Mostly sunny. Isolated showers in the afternoon. Highs 71 to 81. Light winds. Chance of rain 20 percent.

Tonight: Mostly cloudy. Isolated showers in the evening. Lows 51 to 63. Light winds. Chance of rain 20 percent.

Monday: Partly sunny. Scattered showers in the afternoon. Highs 71 to 81. Light winds becoming northeast up to 10 mph in the afternoon. Chance of rain 30 percent.

Detailed Forecast

Synopsis

Rather dry conditions and light winds will persist through the weekend, with limited rainfall favoring windward terrain. An upper level disturbance will pass over the state Monday through Wednesday, bringing a slight increase in shower activity, and potentially popping a thunderstorm or two each afternoon over the Big Island. Light and variable winds will persist Monday, before being replaced by moderate trade winds Monday night and Tuesday. Drier more stable conditions will build back over the islands beginning Wednesday and continuing into next weekend, with moderate trades prevailing.

Discussion

Currently at the surface, a 1018 mb high is centered around 500 miles northeast of Honolulu, while a cold front is positioned around 550 miles northwest of Kauai. These features are producing light trade winds early this morning, with land breezes present in many areas. Infrared satellite imagery shows clear to partly cloudy skies in most areas, with mostly cloudy conditions over windward Big Island. Radar imagery shows a few light showers over windward Big Island, with rain free conditions over the remainder of the state. Main focus during the next few days revolves around rain chances, wind trends and the potential for thunder through the first half of the work week.
High pressure will build eastward and further away from the islands through Monday, while a cold front approaches from the northwest. The front will be losing steam as it nears Kauai late Monday, and may move into the northwestern islands Monday night and Tuesday before washing out. A new high will build in behind the front Tuesday and Wednesday, with ridging holding in place a few hundred miles north of the islands into next weekend. A light wind regime is expected across the state through Monday, with overnight land breezes and daytime sea breezes common in most areas. Moderate north to northeast winds will return Monday night and Tuesday, shift around to more of a typical easterly trade wind direction Wednesday, then potentially become breezy Thursday into next weekend.
As for the remaining details, rather dry weather is expected to persist through tonight, with precipitable water values holding around an inch or less. Limited shower activity will be confined primarily to windward slopes and coasts with most leeward areas not seeing any rain at all. An energetic upper level trough will move over the islands early in the work week, with 500 mb temps dropping down to around -14 to -16C as a couple shortwave impulses dive southeastward through the islands. There will be a subtle increase in moisture associated with the front approaching and moving southward into the islands, but precipitable water values remain unimpressive holding around or slightly above 1 inch. All these elements point to a slight increase in rain chances Monday and Tuesday, with perhaps a few brief heavy showers each afternoon. Given the instability aloft however, a thunderstorm or two is not out of the question over the Big Island even with very low PW values, and have included a mention of thunder each afternoon Monday through Wednesday. Drier and more stable conditions will build back over the islands beginning Wednesday and continuing through late next week, with showers favoring windward and mauka areas.

Aviation

Periods with MVFR CIGS/VSBYS are possible over the windward and southeast sections of the Big Island this morning. Elsewhere, mostly dry and stable pattern will support VFR conditions through the 24-hr TAF cycle. Winds will remain light with early morning land breezes and daytime sea breezes.
AIRMET Sierra for mountain obscuration remains in effect over the windward and southeast sections of the Big Island.

Marine

A low pressure system and cold front passing through the Central Pacific basin this week will continue to keep the surface ridge north of the Hawaiian Islands in a weakened state. Light to locally moderate background trade winds will show more directional variability and remain well below Small Craft Advisory strength through Friday. The cold front will weaken over the northwestern waters on Monday and diminish by Tuesday with increasing shower trends along the frontal boundary.
The current northwest swell will slowly decline today and tonight, while a moderate. Another northwest swell will arrive late Monday, peak on Tuesday, and elevate north shore surf to just below the High Surf Advisory levels. This next northwest swell will slowly decline from Tuesday night into Wednesday. Mainly background south swells are expected through Tuesday, with a slightly larger and longer period south swell possible from Thursday into Friday. Surf heights along east facing shores will remain on the small side through the week.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov