Hilo

Today: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 84 near the shore to 68 to 73 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy in the evening then becoming mostly clear. Isolated showers. Lows around 67 near the shore to around 53 at 4000 feet. Light winds. Chance of rain 20 percent.

Friday: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 85 near the shore to 69 to 74 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Kona

Today: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 81 to 86 near the shore to around 68 near 5000 feet. Light winds. Chance of rain 40 percent.

Tonight: Mostly cloudy in the evening then becoming mostly clear. Lows 68 to 74 near the shore to around 54 near 5000 feet. Light winds.

Friday: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 82 to 87 near the shore to around 69 near 5000 feet. Light winds. 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 82 near the shore to 68 to 79 near 3000 feet. Light winds. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows around 67 near the shore to 55 to 61 near 3000 feet. Light winds. Chance of rain 20 percent.

Friday: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 83 near the shore to 69 to 80 near 3000 feet. Northeast winds up to 10 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 82 near the shore to 68 to 79 near 3000 feet. Light winds. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows around 67 near the shore to 55 to 61 near 3000 feet. Light winds. Chance of rain 20 percent.

Friday: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 83 near the shore to 69 to 80 near 3000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

South Big Island

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 85 near the shore to around 72 near 5000 feet. South winds around 10 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy in the evening then becoming mostly clear. Isolated showers. Lows around 69 near the shore to around 52 near 5000 feet. North winds around 10 mph. Chance of rain 20 percent.

Friday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 86 near the shore to around 73 near 5000 feet. Southeast winds 10 to 15 mph. Chance of rain 40 percent.

Puna

Today: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 84 near the shore to 68 to 73 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy in the evening then becoming mostly clear. Isolated showers. Lows around 67 near the shore to around 53 at 4000 feet. Light winds. Chance of rain 20 percent.

Friday: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 85 near the shore to 69 to 74 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Waikoloa

Today: Mostly sunny with isolated showers 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. Light winds. Chance of rain 50 percent.

Tonight: Partly cloudy. Lows 69 to 74 near the shore to 50 to 57 above 4000 feet. Light winds.

Friday: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 86 near the shore to 70 to 76 above 4000 feet. Light winds. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Light winds remain in the forecast into Friday with local scale land and sea breezes over each island. Clouds and showers will favor island mountain and interior sections each afternoon before clearing out around sunset. Trade winds will then restrengthen this weekend as a high pressure ridge builds back in over the region. A remnant trough associated with former Tropical Cyclone Georgette, will drift westward across the islands enhancing shower activity early Monday into Tuesday.

Discussion

Water vapor satellite imagery this morning shows the upper low north of the state continuing to drift northward away from the Hawaii region. The atmosphere will become more stable as this upper low drifts further away from the islands today. Local radar shows scattered slow moving shower bands developing over marine zones near the islands. Surface observations this morning are showing light land breezes setting up over all islands.
A strong high pressure system far north of the Hawaiian Islands and a surface trough remains north of the islands associated with the upper low. This surface trough will effectively block trade winds over the islands by weakening the surface pressure gradients and producing light winds into Friday. Lighter large scale winds will allow local scale land and sea breezes to strengthen. Daytime island heating will produce converging sea breezes over each island, with clouds and a few showers favoring the afternoon hours over mountain and interior sections. Overnight island cooling will produce down sloping land breezes, stabilizing the air over each island and clearing out most of the cloud cover. A slight increase in trade wind flow will begin to filter back in over the region by Friday afternoon and evening.
Saturday's weather pattern will return to a more typical trade wind pattern, as the surface trough weakens and continues to lift northward allowing a high pressure ridge to build back in over the Hawaii region. The trade winds are forecast to strengthen to moderate to breezy through Sunday. Cloud and shower coverage will return to the more typical windward and mountain areas with passing showers favoring the overnight to early morning hours.
Trade winds continue to blow through the first half of next week. An easterly wave, the remnants of former Tropical Cyclone Georgette, will drift into the Hawaii region early Monday, possibly enhancing showers over the Big Island and Maui, with increasing shower trends spreading westward to Oahu and Kauai on Tuesday. The latest European (ECMWF) model is trending drier with this passing system, while the American (GFS) model shows higher rainfall amounts with more precipitation falling over the Big Island and parts of Maui. We continue to use a blend between these two models for our rainfall forecast this far out into the future.
Long range guidance continues to show the potential for a tropical low passing south of the Big Island around the middle of next week. If this low develops and passes south of the islands, then the trade winds could become stronger than currently forecast as the surface pressure gradient increases. The actual speed of these trade winds will depend heavily upon the intensity of this potential low pressure system, and the proximity to the islands as it passes south of the state.

Aviation

No AIRMETS are currently in effect, and none are anticipated today.
A weak surface trough north of the Hawaiian Islands will cause trade wind speeds to remain relatively light through tonight. This will allow local afternoon sea breezes and nighttime land breezes to develop over each of the individual islands. The weak low-level trade wind flow will transport some low clouds and brief showers into windward facing sections through this morning. This may produce brief periods of MVFR cigs/vis along some windward facing slopes. Otherwise, VFR conditions are expected to prevail this morning.
After the local sea breezes develop this afternoon, there may be increased cloud cover and a chance of showers over interior and leeward sections of the islands. This may result in brief MVFR conditions, but expect VFR conditions to dominate across most of the state. After that, the land breezes setting up starting this evening will tend to clear out the residual clouds and showers over most of the islands tonight.

Marine

An upper low and associated surface trough north of the islands will track northwest of the state the next couple of days. This will result in ongoing gentle trade winds. The upper low will maintain slight chances for northeast offshore water isolated thunderstorm development this morning, along with enhanced shower activity over more eastern island coastal waters. Small Craft Advisories will likely be required this weekend for the notoriously windier east island channels and bays as reestablished high pressure northeast of the region restrengthens trades.
A small, short period northeast swell that picked up more north facing shore surf yesterday will turn more north and fade to the west today. This will keep north surf around waist high or slightly lower through tonight. The passage of a small, medium period east swell from recent eastern Pacific tropical cyclone activity will continue to produce relatively higher surf along east facing shores into Friday. Small background south swells are expected during the remainder of the week. No significant medium to long period swells are expected through early next week.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov