Hilo

Today: Partly sunny in the morning then becoming cloudy. Scattered showers. Highs around 83 near the shore to around 71 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Numerous showers in the evening, then scattered showers after midnight. Lows 64 to 69 near the shore to around 53 at 4000 feet. East winds up to 10 mph shifting to the west after midnight. Chance of rain 60 percent.

Monday: Partly sunny with scattered showers in the morning, then cloudy with numerous showers in the afternoon. Highs around 83 near the shore to around 71 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Kona

Today: Mostly sunny in the morning, then cloudy with scattered showers in the afternoon. Highs 81 to 86 near the shore to around 69 near 5000 feet. Northwest winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 69 to 74 near the shore to around 54 near 5000 feet. Light winds. Chance of rain 30 percent.

Monday: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 81 to 86 near the shore to around 69 near 5000 feet. Northwest winds up to 10 mph. Chance of rain 40 percent.

Waimea

Today: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 81 near the shore to 68 to 78 near 3000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 66 near the shore to 51 to 61 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Monday: Breezy. Mostly sunny with isolated showers in the morning, then cloudy with scattered showers in the afternoon. Highs around 81 near the shore to 68 to 78 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Kohala

Today: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 81 near the shore to 68 to 78 near 3000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 66 near the shore to 51 to 61 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Monday: Breezy. Mostly sunny with isolated showers in the morning, then cloudy with scattered showers in the afternoon. Highs around 81 near the shore to 68 to 78 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

South Big Island

Today: Breezy. Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 85 near the shore to around 72 near 5000 feet. East winds up to 20 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows around 70 near the shore to around 53 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Monday: Breezy. Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 85 near the shore to around 72 near 5000 feet. East winds up to 20 mph. Chance of rain 40 percent.

Puna

Today: Partly sunny in the morning then becoming cloudy. Scattered showers. Highs around 83 near the shore to around 71 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Numerous showers in the evening, then scattered showers after midnight. Lows 64 to 69 near the shore to around 53 at 4000 feet. East winds up to 10 mph shifting to the west after midnight. Chance of rain 60 percent.

Monday: Partly sunny with scattered showers in the morning, then cloudy with numerous showers in the afternoon. Highs around 83 near the shore to around 71 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Waikoloa

Today: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 85 near the shore to 69 to 75 above 4000 feet. Northwest winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows around 72 near the shore to 50 to 58 above 4000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Monday: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 85 near the shore to 69 to 75 above 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

The hybrid trade wind and sea breeze pattern will continue on today, as clouds build over leeward slopes of each island in the afternoon hours, with some showers lingering from the afternoon to the evening hours. An upper level disturbance will enhance cloud and shower activity today and tonight. A high pressure system far north of the Hawaiian Islands will build into the region on Monday, increasing trade wind speeds to the moderate to locally breezy range through Friday. Fairly typical cloud and shower trends will return with passing showers over the windward and mountain areas of each island, favoring the overnight to early morning hours.

Discussion

Large scale satellite imagery this morning shows unstable cumulus clouds drifting into region on the trade winds. An upper level low shown on satellite water vapor imagery near Kauai with a trough reaching eastward across the rest of the state will continue to enhance shower activity today and tonight. Clouds and showers today will favor both the windward areas and western slopes of each island in a hybrid trade wind and sea breeze pattern. Local radar imagery this morning continues to show scattered to numerous showers developing across the region. Cirrus clouds from the subtropical jet stream are drifting over the southeast islands today. These ice crystal clouds will spread slowly northward to all islands through the work week.
A hybrid trade wind and sea breeze weather pattern will continue on today with sea breezes building clouds over leeward areas each afternoon. An upper level low north of Kauai is producing a weak troughing pattern aloft, lifting the trade wind inversion height today into the 8,000 to 10,000 foot range based on the morning upper air balloon soundings from Lihue and Hilo respectively. Expect enhanced showers to continue for one more day as this low and trough pattern drift westward away from the island chain. Otherwise, a high pressure system far north of the state will build into the region on Monday and strengthen the trade winds from the current light to moderate levels into the moderate to locally breezy range. These stronger trade winds will weaken the sea breezes along terrain sheltered western slopes of the smaller islands and bring a more typical trade wind weather pattern to the region.
Model cross sections show variability in the trade wind inversion height each day this week. Trade wind inversion heights will range from around 6,000 to 8,000 feet from Monday onward, which will keep passing showers in the forecast mainly over windward and mountain areas. These windward shower amounts will be light and favor the overnight to early morning hours. Leeward slopes of the smaller islands however will remain on the dry side with only isolated showers possible. The western slopes of the Big Island may continue to see isolated to scattered showers each afternoon to early evening in a persistent sea breeze regime.

Aviation

Light to moderate trades will persist into tonight, with localized land and sea breezes expected in some of the more sheltered leeward areas. Although VFR conditions will prevail for most areas, expect brief periods of MVFR CIGS/VSBYS in and around showers that develop and move through. The exception is over the eastern end of the state, where MVFR conditions are being observed over a larger area early this morning. As a result, AIRMET Sierra remains in effect for mountain obscuration across windward/SE sections of the Big Island and windward Maui. These conditions may continue through the morning hours before improving.

Marine

Trade winds will hold at gentle to moderate speeds through tonight as a front passes between the islands and a surface high well north of Kauai. High pressure will build far northeast of the state Sunday night, leading to an increase in trade winds Monday. A Small Craft Advisory will likely be issued tonight for the typically windy waters around the Big Island and Maui through at least the middle of the week, and likely through next weekend.
Two pulses of south swell will produce elevated south shore surf this week. The first swell is now showing up at the nearshore buoys, with Barbers Point coming in at 2 feet 18 seconds at the latest observation. Surf will build along local south shores today as this swell fills in. Surf is expected to peak a couple of feet overhead Monday, then build to near advisory level of 10 feet Tuesday and Wednesday as the next, larger, pulse arrives. South swell and surf will gradually decline Thursday and Friday.
Surf along exposed north and east facing shores will see a bump in small, short period swell today into Monday. Surf along north shores will drop Tuesday, while strengthening trade winds will boost rough east shore surf to around seasonal average.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov