Hilo

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 62 to 69 near the shore to 50 to 56 at 4000 feet. North winds up to 10 mph. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 74 to 81 near the shore to 63 to 68 at 4000 feet. North winds up to 15 mph. Chance of rain 40 percent.

Saturday Night: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 62 to 68 near the shore to 49 to 55 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Kona

Tonight: Partly cloudy with isolated showers. Lows around 71 near the shore to 44 to 52 near 5000 feet. Light winds. Chance of rain 20 percent.

Saturday: Mostly sunny. Isolated showers in the afternoon. Highs 82 to 87 near the shore to around 69 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Saturday Night: Partly cloudy. Isolated showers after midnight. Lows around 71 near the shore to 44 to 52 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Isolated showers. Lows 62 to 70 near the shore to 54 to 60 near 3000 feet. East winds up to 25 mph. Chance of rain 20 percent.

Saturday: Breezy. Mostly sunny with isolated showers. Highs 72 to 79 near the shore to 67 to 76 near 3000 feet. East winds 10 to 25 mph. Chance of rain 20 percent.

Saturday Night: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Isolated showers. Lows 62 to 70 near the shore to 53 to 59 near 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Kohala

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Isolated showers. Lows 62 to 70 near the shore to 54 to 60 near 3000 feet. East winds up to 25 mph. Chance of rain 20 percent.

Saturday: Breezy. Mostly sunny with isolated showers. Highs 72 to 79 near the shore to 67 to 76 near 3000 feet. East winds 10 to 25 mph. Chance of rain 20 percent.

Saturday Night: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Isolated showers. Lows 62 to 70 near the shore to 53 to 59 near 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

South Big Island

Tonight: Mostly clear. Breezy. Lows around 71 near the shore to around 49 near 5000 feet. Northeast winds 10 to 25 mph decreasing to up to 20 mph after midnight.

Saturday: Sunny and breezy. Highs around 83 near the shore to around 67 near 5000 feet. East winds up to 25 mph.

Saturday Night: Mostly clear. Lows around 71 near the shore to around 49 near 5000 feet. Northeast winds 10 to 15 mph.

Puna

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 62 to 69 near the shore to 50 to 56 at 4000 feet. North winds up to 10 mph. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 74 to 81 near the shore to 63 to 68 at 4000 feet. North winds up to 15 mph. Chance of rain 40 percent.

Saturday Night: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 62 to 68 near the shore to 49 to 55 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Waikoloa

Tonight: Mostly clear. Breezy. Lows around 72 near the shore to 49 to 54 above 4000 feet. Southeast winds up to 20 mph.

Saturday: Sunny and windy. Highs 81 to 88 near the shore to 66 to 73 above 4000 feet. Northeast winds up to 30 mph.

Saturday Night: Mostly clear. Lows around 71 near the shore to 48 to 54 above 4000 feet. East winds up to 10 mph.

Detailed Forecast

Synopsis

A relatively dry moderate to breezy trade wind pattern will continue into the weekend as high pressure lingers north of the Hawaiian Islands. Then light winds are expected through the first half of next week as a cold front approaches from the northwest. This front may drift into the islands by the end of the week, potentially increasing showers.

Discussion

Current visible satellite and radar imagery show partly to mostly cloudy skies across the state, with a few showers focused over windward slopes. The afternoon (00Z) soundings from Lihue and Hilo showed inversions at approximately 4500 and 7000 feet, respectively, with plenty of dry air aloft from a broad upper ridge over and just north of the state. These stable conditions will keep rainfall pretty minimal through the rest of the afternoon.
An elongated surface ridge of high pressure north of the islands will maintain moderate to locally breezy trade winds through the weekend. Fairly dry trade wind weather will prevail through this period, with brief passing showers mainly focused over windward and mauka areas, favoring the overnight to early morning hours.
Then heading into next week, large scale winds will transition to a more light and variable pattern from Monday through Wednesday as a cold front approaches the state from the northwest. This lighter flow will allow for the development of land and sea breezes to expand in coverage across the state by Wednesday. Weak ridging aloft will keep fairly stable conditions in place, with sea breezes focusing clouds and limited shower activity over interior and leeward areas each afternoon and land breezes helping to clear out cloud cover overnight.
Current model guidance suggests that the aforementioned cold front will move into Hawaii during the second half of next week as it weakens, potentially bringing our next chance for better rainfall coverage. However, despite model differences, latest runs are indicating that overall rainfall amounts would be rather insignificant.

Aviation

AIRMET Tango is in effect for moderate low-level turbulence over and downwind of the terrain of all islands that will likely continue into Saturday as winds remain breezy. Brief mountain obscurations may occur over windward areas through tonight. Possible for AIRMET Sierra tonight for mountain obscurations over windward sides of the islands as cloud cover fills in from upstream.

Marine

High pressure to the north of the Hawaiian Islands will keep fresh to locally strong easterly trade winds in place through Sunday. Trade winds are expected to ease Sunday night into early next week as the ridge weakens. Winds and seas are currently at or near Small Craft Advisory levels for most waters from Oahu eastward, which will persist through Saturday before subsiding below thresholds Sunday. Starting Sunday night, light and variable winds will develop near the coasts, accompanied by overnight and early morning land breezes and daytime sea breezes, then expand to most of the coastal waters for Monday and Tuesday. Winds will shift out of the southwest then west over the western half of the island chain by Wednesday as a front approaches from the northwest, followed by moderate to locally fresh north-northeast winds as the front progresses eastward.
Surf along exposed north and west-facing shores will hold at moderate levels through this evening as a northwest swell lingers, with a gradual decrease expected later tonight through Monday as the swell eases. By Tuesday, increasing long-period west-northwest swell (330) will begin filling in, driven by a decent-sized fetch developing over the far northwest Pacific. Surf will rise accordingly, with a significant upward trend anticipated through the second half of next week. Heights could exceed warning- levels (XL: 25-39 ft faces) late next week if conditions evolve as projected.
Surf along east-facing shores will remain rough through the weekend, but will gradually decrease late Sunday and into much of next week as the trade winds diminish. Surf along south-facing shores will remain near seasonal averages.
Coastal flooding along the shorelines and low-lying coastal areas will be possible Saturday and Sunday due to a combination of peak monthly high tides and above normal water levels. Coastal flooding will be mist likely during the early morning high tides. See the Coastal Flood Statement now in effect for more details.

Fire weather

While rather dry conditions are expected through much of the forecast period, wind speeds and relative humidity levels will not reach critical fire weather thresholds through next week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Saturday for Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Windward Waters, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov