Hilo

Today: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to around 72 at 4000 feet. North winds up to 20 mph shifting to the northeast 10 to 20 mph in the afternoon. Chance of rain 70 percent.

Tonight: Breezy and showers. Lows around 69 near the shore to around 55 at 4000 feet. North winds 10 to 20 mph. Chance of rain near 100 percent.

Saturday: Mostly cloudy. Breezy. Showers in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to around 72 at 4000 feet. Northeast winds 10 to 20 mph. Chance of rain 90 percent.

Kona

Today: Mostly sunny. Haze through the day. Scattered showers in the afternoon. Highs around 85 near the shore to around 74 near 5000 feet. East winds up to 10 mph shifting to the northwest in the afternoon. Chance of rain 50 percent.

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Haze through the night. Lows 69 to 75 near the shore to around 55 near 5000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Saturday: Mostly sunny. Haze through the day. Scattered showers in the afternoon. Highs around 85 near the shore to around 74 near 5000 feet. Southeast winds up to 10 mph. Chance of rain 50 percent.

Waimea

Today: Breezy. Partly sunny with scattered showers. Highs around 82 near the shore to 74 to 81 near 3000 feet. East winds 10 to 25 mph increasing to 20 to 25 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Numerous showers in the evening, then scattered showers after midnight. Lows around 68 near the shore to 56 to 63 near 3000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Saturday: Windy. Partly sunny with scattered showers. Highs around 82 near the shore to 74 to 80 near 3000 feet. East winds 10 to 30 mph. Chance of rain 50 percent.

Kohala

Today: Breezy. Partly sunny with scattered showers. Highs around 82 near the shore to 74 to 81 near 3000 feet. East winds 10 to 25 mph increasing to 20 to 25 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Numerous showers in the evening, then scattered showers after midnight. Lows around 68 near the shore to 56 to 63 near 3000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Saturday: Windy. Partly sunny with scattered showers. Highs around 82 near the shore to 74 to 80 near 3000 feet. East winds 10 to 30 mph. Chance of rain 50 percent.

South Big Island

Today: Sunny and windy. Haze through the day. Isolated showers in the afternoon. Highs around 85 near the shore to around 75 near 5000 feet. East winds 10 to 30 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Windy. Isolated showers in the evening. Haze through the night. Lows around 69 near the shore to around 54 near 5000 feet. Northeast winds 10 to 30 mph. Chance of rain 20 percent.

Saturday: Sunny and windy. Haze through the day. Isolated showers in the afternoon. Highs around 85 near the shore to around 75 near 5000 feet. East winds 10 to 30 mph. Chance of rain 20 percent.

Puna

Today: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to around 72 at 4000 feet. North winds up to 20 mph shifting to the northeast 10 to 20 mph in the afternoon. Chance of rain 70 percent.

Tonight: Breezy and showers. Lows around 69 near the shore to around 55 at 4000 feet. North winds 10 to 20 mph. Chance of rain near 100 percent.

Saturday: Mostly cloudy. Breezy. Showers in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to around 72 at 4000 feet. Northeast winds 10 to 20 mph. Chance of rain 90 percent.

Waikoloa

Today: Sunny and windy. Highs 82 to 87 near the shore to 71 to 76 above 4000 feet. East winds up to 25 mph shifting to the northeast in the afternoon. Gusts up to 50 mph.

Tonight: Mostly clear. Windy. Lows 70 to 75 near the shore to 51 to 58 above 4000 feet. East winds 10 to 30 mph decreasing to up to 20 mph after midnight. Gusts up to 50 mph.

Saturday: Sunny and breezy. Highs 82 to 87 near the shore to 71 to 76 above 4000 feet. East winds up to 20 mph with gusts to 45 mph.

Detailed Forecast

Synopsis

A strong high pressure system north of the islands will drift closer to the islands through the weekend producing breezy to windy trade winds across the state. Clouds and passing showers will continue to favor windward and mountain areas with more scattered shower activity drifting into leeward areas through Saturday favoring the overnight to early morning hours. Increasing moisture and shower trends are forecast from Sunday through Tuesday as two unstable disturbances pass through the region. Drier trends are forecast from Wednesday onward as stability returns to the region.

Discussion

The satellite imagery this morning shows clouds moving in on the trade winds into the windward sections of each island. A narrow upper level trough is located just north of the islands with embedded upper lows drifting within the trough. One of these upper lows is deepening northeast of the region this low will increase moisture levels and enhance shower activity from Sunday into Tuesday. A subtropical jet stream south of this upper trough will produce periods of high level cirrus clouds drifting from southwest to northeast across the state, enhancing sunrise and sunset colors.
A strong high pressure system far north of the state will drift slightly south through the weekend. Local surface pressure gradients will increase starting today producing increasing wind speeds into the breezy to windy range into Sunday. The strongest winds will occur near mountains, valleys and over leeward areas. A Wind Advisory remains in effect for mountain and leeward areas of all Hawaiian Islands through Saturday afternoon. This Wind Advisory may need to be extended into Sunday based on updated forecast guidance. Wind speeds will decrease a bit by early next week into the moderate to breezy range from Monday through Wednesday.
Weather wise, expect clouds and passing showers will continue to favor windward and mountain areas with more scattered shower activity drifting into leeward areas through Saturday. By Sunday an upper level disturbance drifting in north of the region and a low level trough will increase moisture levels and weaken the trade wind temperature inversion over the islands. Precipitable Water (PW) levels will increase from 1.0 to 1.5 inches on Saturday into the 1.5 to 2.0 inch range from Sunday into Tuesday. In this breezy trade wind pattern expect shower activity to increase as moisture levels rise and clouds build over island terrain features. Long range guidance shows more stable conditions and decreasing shower trends developing from Wednesday onward.

Aviation

High pressure strengthening north of the state will bring breezy to windy trade winds to the islands today. Thus, expect scattered to numerous showers along windward locations…especially this morning. Brief periods of MVFR conditions will likely accompany this activity. Isolated showers may push over the elevated terrain and onto leeward areas through the forecast period.
AIRMET TANGO remains in effect below 8000 feet over and immediately south through west of all mountains for tempo moderate turbulence.

Marine

A series of strong highs building far to the north of the islands will keep strong trade winds in place through the middle of next week. The trades will be at their strongest tonight through the weekend, before trending down slightly during the first half of next week. A Small Craft Advisory (SCA) remains in effect for all marine zones today due to winds/seas or a combination of the two. As the trades winds peak tonight through Sunday, Gale force winds will be possible in the typically windy waters around Maui and the Big Island, and as a result, a Gale Watch is now in effect for these areas during this time. Elsewhere, a SCA remains in effect through 6 PM Sunday.
Long period forerunners from a building south swell have begun to arrive at the nearshore buoys south of Oahu early this morning. This swell is expected to build today and tonight, then peak over the weekend. Although the bulk of the swell energy will pass east of Hawaii, advisory level surf remains a possibility Saturday into Sunday as the swell peaks. South shore surf will lower early next week, but a reinforcing south swell will likely keep south shore surf above normal levels through the middle of next week. Surf along east facing shores will build today, and become very rough tonight through the weekend as the trade winds will be blasting. East shore surf will rise to well above seasonal levels by this afternoon, then likely reach advisory levels Saturday through Monday. The trades will trend down early next week, so we should see the very rough conditions improve ever so slightly, with a gradual and slow lowering of east shore surf through the middle of next week. The current west-northwest swell will continue to gradually fade out today. No other significant northwest swells are expected through the middle of next week.

Fire weather

Breezy to windy trade winds and low humidity levels will exceed Red Flag Warning (RFW) thresholds over leeward areas of the Hawaiian Islands through Saturday afternoon. Wind speeds will continue to strengthen into the weekend. Moisture levels are forecast rise on Sunday, decreasing the potential for extreme fire behavior.

HFO Watches/Warnings/Advisories

Red Flag Warning until 6 PM HST Saturday for most leeward areas of all Hawaiian Islands.
Wind Advisory until 6 PM HST Saturday for most mountain and leeward areas of all Hawaiian Islands.
Gale Watch from this evening through Sunday afternoon 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 Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 PM HST Sunday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.

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Data Courtesy of NOAA.gov