Photo Credit: James Grenz

Hilo

Today: Cloudy with numerous showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 86 near the shore to 71 to 76 at 4000 feet. Northeast winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 70 percent.

Tonight: Cloudy. Numerous showers in the evening, then showers after midnight. Lows around 70 near the shore to around 56 at 4000 feet. Northwest winds up to 15 mph shifting to the north after midnight. Chance of rain 80 percent.

Wednesday: Mostly cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 86 near the shore to 71 to 76 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Kona

Today: Mostly sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs 84 to 89 near the shore to around 71 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 71 to 76 near the shore to around 57 near 5000 feet. Light winds. Chance of rain 20 percent.

Wednesday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 84 to 89 near the shore to around 71 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Waimea

Today: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 84 near the shore to 71 to 81 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 70 near the shore to 58 to 64 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Wednesday: Breezy. Partly sunny with isolated showers. Highs around 84 near the shore to 71 to 81 near 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Kohala

Today: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 84 near the shore to 71 to 81 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 70 near the shore to 58 to 64 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Wednesday: Breezy. Partly sunny with isolated showers. Highs around 84 near the shore to 71 to 81 near 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

South Big Island

Today: Breezy. Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 88 near the shore to around 75 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening. Lows around 72 near the shore to around 55 near 5000 feet. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Wednesday: Mostly sunny in the morning then becoming partly sunny. Breezy. Highs around 88 near the shore to around 75 near 5000 feet. East winds 10 to 20 mph decreasing to up to 20 mph in the afternoon.

Puna

Today: Cloudy with numerous showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 86 near the shore to 71 to 76 at 4000 feet. Northeast winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 70 percent.

Tonight: Cloudy. Numerous showers in the evening, then showers after midnight. Lows around 70 near the shore to around 56 at 4000 feet. Northwest winds up to 15 mph shifting to the north after midnight. Chance of rain 80 percent.

Wednesday: Mostly cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 86 near the shore to 71 to 76 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Waikoloa

Today: Breezy. Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 88 near the shore to 72 to 78 above 4000 feet. East winds up to 20 mph shifting to the northeast in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 74 near the shore to 53 to 60 above 4000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Wednesday: Sunny in the morning then becoming partly sunny. Breezy. Highs around 88 near the shore to 72 to 78 above 4000 feet. Northeast winds up to 20 mph.

Detailed Forecast

Synopsis

Expect moderate to locally breezy trade winds lasting through Wednesday with passing clouds and showers favoring windward and mountain areas. A low level trough passing over the islands will enhance shower activity across the state through the morning hours. Trade winds will weaken on Thursday, as we transition to a more hybrid windward trade wind and leeward sea breeze regime from Friday through Monday. In this hybrid wind pattern clouds and scattered showers will favor mountain and island interior sections each afternoon and then shift to windward areas during the overnight time periods.

Discussion

A low level trough passing through the islands this evening will bring periods of showers to each island, favoring windward and mountain areas. Satellite imagery this evening supports these short term shower trends with more unstable cloud bands drifting in on the trade winds. A weak subtropical jet stream over the islands will bring a few high cirrus clouds to the region this week.
A high pressure system far north of the Hawaiian Islands will slowly drift east through the week keeping moderate to locally breezy trade winds in the forecast through Wednesday. A low level trough will pass west of the state later this morning. Drying trends will develop by the afternoon hours as more stable conditions move into the region from the east. Otherwise passing showers will favor windward and mountain areas into Thursday, mainly in the overnight to early morning hours.
On Thursday the weather pattern begins to transition to a hybrid windward light trades and leeward sea breeze pattern. By Friday large scale trade winds decrease even further, allowing sea breezes to strengthen over leeward areas. Surface heating over each island and sea breeze trade wind convergence will produce clouds and showers over mountains and island interior sections from afternoon to early evening. This hybrid wind pattern will last through the weekend into early next week. One wrinkle in the forecast are two weak troughs moving through northeast trade wind background flow. These are likely remnants of an old cold front that dissipated in the northeast Pacific drifting into the islands. These cloud bands will likely increase windward and mountain clouds and showers a bit, mainly in the overnight to early morning hours from Friday through Sunday. The forecast guidance agrees with the wetter trends during this lighter trade wind period, however the timing of these rainfall impacts varies from model to model. Will likely trend our precipitation chances a bit higher for windward areas in the morning forecast grids for this extended time period.

Aviation

Moderate to locally breezy trade winds will continue through tonight. A band of enhanced moisture will move from east to west through the island chain early this morning, bringing showery weather to windward areas and allowing a few more showers to reach leeward communities as well. Drier more stable conditions are expected statewide this afternoon.
AIRMET Sierra remains in effect for windward sections of Kauai, Oahu, Molokai, Maui and the Big Island. Conditions should improve from east to west across the island chain this morning.

Marine

High pressure north of the state will drive moderate to locally strong trade winds across local waters through most of the coming week. A brief trade wind increase is expected as a band of showers pushes through the area. A Small Craft Advisory for the typically windier waters around Maui County and Big Island has been issued through 6 am HST Wednesday.
Surf along south facing shores will remain steady this week into Thursday producing near seasonal average surf heights. A gale low in the Tasman Sea will send a moderate south southwest swell towards Hawaii this weekend. A series of small, medium period north swells will provide a minor bump through the end of the week for north facing shores. Near term east wind wave chop will remain slightly elevated under moderate to fresh trades over and upstream of the islands. East swell generated from eastern Pacific Tropical Cyclone Kay may also arrive over the weekend.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov