Hilo

Today: Partly sunny in the morning then becoming cloudy. Scattered showers. Highs around 84 near the shore to 68 to 73 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 64 to 72 near the shore to 54 to 59 at 4000 feet. East winds 10 to 15 mph shifting to the northeast after midnight. Chance of rain 50 percent.

Monday: Cloudy with scattered showers. Highs around 82 near the shore to 66 to 74 at 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Kona

Today: Sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs 80 to 85 near the shore to around 68 near 5000 feet. East winds around 10 mph shifting to the southwest in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows around 72 near the shore to 50 to 55 near 5000 feet. South winds around 10 mph in the evening becoming light. Chance of rain 20 percent.

Monday: Mostly sunny in the morning then becoming mostly cloudy. Isolated showers. Highs 83 to 88 near the shore to around 69 near 5000 feet. Northwest winds around 10 mph. Chance of rain 20 percent.

Waimea

Today: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 82 near the shore to 69 to 79 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows around 65 near the shore to 55 to 62 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Monday: Breezy. Mostly cloudy with isolated showers. Highs 67 to 87. East winds 10 to 20 mph. Chance of rain 20 percent.

Kohala

Today: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 82 near the shore to 69 to 79 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows around 65 near the shore to 55 to 62 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Monday: Breezy. Mostly cloudy with isolated showers. Highs 67 to 87. East winds 10 to 20 mph. Chance of rain 20 percent.

South Big Island

Today: Breezy. Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 85 near the shore to around 72 near 5000 feet. East winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers after midnight. Lows around 72 near the shore to around 52 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Monday: Breezy. Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 84 near the shore to around 68 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Puna

Today: Partly sunny in the morning then becoming cloudy. Scattered showers. Highs around 84 near the shore to 68 to 73 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 64 to 72 near the shore to 54 to 59 at 4000 feet. East winds 10 to 15 mph shifting to the northeast after midnight. Chance of rain 50 percent.

Monday: Cloudy with scattered showers. Highs around 82 near the shore to 66 to 74 at 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Waikoloa

Today: Sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs around 85 near the shore to 69 to 75 above 4000 feet. East winds around 10 mph shifting to the north in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers after midnight. Lows 69 to 74 near the shore to 49 to 56 above 4000 feet. Northeast winds 10 to 15 mph shifting to the east after midnight. Chance of rain 20 percent.

Monday: Sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs 80 to 88 near the shore to 67 to 73 above 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Locally breezy trades will focus clouds and showers over windward areas through the week. An increase in showers is expected Wednesday and Thursday.

Discussion

A stable and locally breezy trade wind flow is in place this morning. Windward showers are on a brief decline as a pocket of moisture in the trade winds is in the process of clearing the islands to the west. Ridging aloft is building in from the east as a small and weak upper level trough moves west of Kauai. As a result, trade winds have picked up slightly and will remain elevated today. Also, strong east to southeast winds have been observed on the Haleakala summit overnight and are expected to develop on the Big Island summits this morning. A Wind Advisory remains in place through the afternoon for the Haleakala summit and through tonight on the Big Island summits, but this advisory may be dropped earlier on the Big Island if winds fail to materialize.
Moderate to breezy trade winds will continue through the upcoming week, and a rather typical pattern of mainly windward rainfall will prevail much of the time. An increase in rainfall is possible Wednesday and Thursday as a larger batch of enhanced low level moisture is accompanied by another weak upper level trough. Heavy rainfall is not expected, though passing showers may become more prevalent over parched leeward areas.

Aviation

Breezy easterly trade winds will continue through the 24-hr period, with clouds and showers favoring windward and mauka locations overnight through the morning periods. A large area of low clouds that led to AIRMET Sierra for mountain obscuration over windward portions of the Big Island through much of the night has begun to scattered out. Observations reflect that with improving trends and a return of VFR conditions as of this discussion time. If this persist through the early morning hours, AIRMET Sierra will be lifted in the 530 AM forecast package. Elsewhere, MVFR CIGS continue for windward areas of Maui County and Oahu and may persist through the early morning hours before scattering out.
AIRMET Tango is in effect for low-level mechanical turbulence over and just downwind of mountain ranges.

Marine

A high pressure ridge remains in place north of the region through Friday. Moderate to locally strong trade winds will continue through the week reaching Small Craft Advisory (SCA) thresholds in the typical windier eastern waters and channels. The SCA was extended for the Kaiwi Channel today. SCA conditions will continue for windier eastern waters near Maui and Hawaii Counties through 6 PM HST Tuesday. This SCA will likely continue for these eastern waters through next Friday.
Small surf heights will continue for the foreseeable future. Background south swell will continue through Wednesday. A slight bump in long period southwest swell energy (210-220 direction) will show up along south facing shores from Thursday into Friday. A small medium period west-northwest (300 direction) swell will fill into the islands tonight through Monday. This first swell will then slowly fade through Wednesday. Another larger long period west-northwest swell (300 direction) arrives in the islands on Thursday producing out of season fun size surf along north and west facing shores lingering into the weekend. Choppy surf along east facing shores will build closer to seasonal averages through the week as trade winds strengthen this weekend.

HFO Watches/Warnings/Advisories

Wind Advisory until 6 AM HST Monday for Big Island Summits.
Wind Advisory until 6 PM HST this evening for Haleakala Summit.
Small Craft Advisory until 6 PM HST Tuesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 PM HST this evening for Kaiwi Channel.

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Data Courtesy of NOAA.gov