Hilo

Today: Mostly sunny with scattered showers. Highs 80 to 86 near the shore to around 71 at 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Tonight: Partly cloudy with isolated showers. Lows around 65 near the shore to around 51 at 4000 feet. Northeast winds up to 10 mph shifting to the southwest after midnight. Chance of rain 20 percent.

Friday: Mostly sunny. Scattered showers in the afternoon. Highs 80 to 86 near the shore to around 72 at 4000 feet. Light winds becoming east up to 10 mph in the afternoon. Chance of rain 40 percent.

Kona

Today: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 85 near the shore to around 71 near 5000 feet. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows 68 to 73 near the shore to around 53 near 5000 feet. Light winds.

Friday: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 80 to 85 near the shore to around 69 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs around 82 near the shore to 73 to 80 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows around 64 near the shore to 51 to 58 near 3000 feet. East winds 10 to 15 mph shifting to the southeast after midnight. Chance of rain 40 percent.

Friday: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 82 near the shore to 73 to 80 near 3000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Kohala

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs around 82 near the shore to 73 to 80 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows around 64 near the shore to 51 to 58 near 3000 feet. East winds 10 to 15 mph shifting to the southeast after midnight. Chance of rain 40 percent.

Friday: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 82 near the shore to 73 to 80 near 3000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

South Big Island

Today: Mostly sunny. Highs around 85 near the shore to around 74 near 5000 feet. East winds up to 15 mph.

Tonight: Mostly clear. Lows around 65 near the shore to around 50 near 5000 feet. Northeast winds up to 15 mph.

Friday: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 85 near the shore to around 74 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Puna

Today: Mostly sunny with scattered showers. Highs 80 to 86 near the shore to around 71 at 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Tonight: Partly cloudy with isolated showers. Lows around 65 near the shore to around 51 at 4000 feet. Northeast winds up to 10 mph shifting to the southwest after midnight. Chance of rain 20 percent.

Friday: Mostly sunny. Scattered showers in the afternoon. Highs 80 to 86 near the shore to around 72 at 4000 feet. Light winds becoming east up to 10 mph in the afternoon. Chance of rain 40 percent.

Waikoloa

Today: Sunny. Highs around 84 near the shore to 68 to 74 above 4000 feet. Northwest winds up to 10 mph.

Tonight: Mostly clear. Lows around 70 near the shore to 50 to 57 above 4000 feet. Southeast winds up to 10 mph in the evening becoming light.

Friday: Sunny. Highs around 84 near the shore to 69 to 75 above 4000 feet. Light winds.

Detailed Forecast

Synopsis

Light to moderate trade winds will continue through this evening. Low clouds and light showers carried by the trades will move over windward facing sections of the state today, especially on Kauai and Oahu this morning. Light and variable winds with dry weather conditions are expected from Friday into early next week, which will allow afternoon sea breezes and nighttime land breezes to develop. This may result in clouds and a chance of showers over leeward and interior sections of the islands each afternoon, followed by clearing skies at night.

Discussion

A 1032 mb surface high pressure system is located near 39N 161W, or more than 1200 miles north of Honolulu. This feature, which is moving east at about 20 mph, is pushing a front down toward the state early this morning. The leading edge of the band of broken to locally overcast low clouds and showers associated with this front is about 220 miles north-northwest of Lihue. This leading edge has been moving south-southeast at less than 10 mph.
The atmosphere over the islands remains relatively stable, but there has been a slight uptick in low-level moisture near the western islands overnight. Loops of satellite imagery and radar reflectivity data show scattered to broken low clouds with embedded scattered light showers streaming down toward the northeast sections of Oahu and Kauai. There are also scattered to locally broken low clouds and isolated light showers just upstream of east Maui and the Big Island. We expect these low clouds and showers will continue moving into windward and mauka sections of some of the islands this morning, especially on Kauai and Oahu.
The latest forecast guidance continues to indicate the front will eventually stall and rapidly deteriorate later this morning about 175 miles north of Lihue. The pressure gradient south of the surface high pressure system far north of the state will likely remain just tight enough to keep light to moderate trade winds in our forecast through this evening. The trades may still be weak enough to allow local sea breeze circulations to form over some sheltered leeward locations this afternoon. If so, clouds and a few brief showers may develop over some leeward sections later today. Otherwise, expect the low-level trade wind flow to continue to transport low clouds and light trade showers into windward and mauka sections of the island chain from this afternoon into this evening.
The forecast models show the surface high pressure system moving rapidly northeast tonight, and by Friday a weak surface ridge is expected to be in the vicinity of the islands. This will disrupt the trades, and produce light and variable winds from this weekend into early next week. As a result, expect a weather pattern with alternating local afternoon sea breeze and nighttime land breeze circulations over each of the individual islands for several days. The atmosphere will also be dry and stable. Some clouds and a few brief showers may develop over leeward and interior sections of the islands each afternoon. However, the downslope winds, which will develop soon after dusk each evening, will likely result in mostly clear skies during the nighttime and morning hours.

Aviation

Light to moderate trade winds will continue for the next few days. An area of increased clouds and showers drifting southward across Kauai and Oahu may cause brief mountain obscuration, MVFR visibility and ceilings through this morning. No AIRMETS are in effect now, but AIRMET Sierra for tempo mountain obscuration may be needed later if conditions warrant.

Marine

A cold front will become stationary across the far north offshore waters this morning. A weak ridge axis extending from northeast high pressure between this boundary and the state will maintain gentle to moderate trade winds through Friday night. The next cold front approaching the region from the northwest will skirt off to the east just north of the far offshore waters Saturday. The very weak pressure gradient downstream of this front, along with the lingering ridge axis that will be over the state Saturday, will produce very anemic light and variable breezes from this weekend through early next week.
North facing shore surf heights will gradually lower early today but at a slower pace due to an overlapping small, medium period northwest swell filling in behind this past week’s diminishing northwest swell. A slightly larger, shorter period north northwest swell will arrive this afternoon, peak tonight and then subside from early Friday into the weekend. A large north swell is timed to reach the island chain Saturday night and peak Sunday. This swell will increase early week north shore surf heights to above High Surf Advisory thresholds, possibly as high as low-end High Surf Warning levels. This advisory level surf will begin to fall Monday but a reinforcement northwest swell Tuesday will maintain advisory to potentially warning level surf along north and west facing shores into the middle of next week. A few slightly larger, lower period south southeast swells have reached the islands and are providing a minor bump to southern shore surf. A couple of late season small, medium period south swells coming in the next few days will hold current south facing shore surf heights through the weekend. Surf along directly east facing shores, with the exception of more northern or southern exposures experiencing a higher north or south swell wrap, will exhibit a very small chop through early next week in response to light and variable breezes.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov