Hilo

Today: Mostly cloudy. Showers in the morning, then scattered showers in the afternoon. Highs 74 to 81 near the shore to around 62 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 80 percent.

Tonight: Mostly cloudy with showers. Lows 60 to 69 near the shore to around 53 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 80 percent.

Friday: Mostly cloudy. Showers in the morning, then showers likely in the afternoon. Highs 74 to 80 near the shore to around 63 at 4000 feet. North winds up to 10 mph shifting to the east in the afternoon. Chance of rain 80 percent.

Kona

Today: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 83 near the shore to around 65 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly clear. Lows 67 to 72 near the shore to 46 to 53 near 5000 feet. Light winds.

Friday: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 83 near the shore to around 65 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Waimea

Today: Mostly cloudy. Breezy. Showers likely in the morning, then scattered showers in the afternoon. Highs 61 to 82. East winds 10 to 25 mph with gusts to 45 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with showers likely. Lows 59 to 64 near the shore to 51 to 60 near 3000 feet. East winds up to 25 mph. Gusts up to 45 mph in the evening. Chance of rain 60 percent.

Friday: Partly sunny. Breezy. Showers likely in the morning, then scattered showers in the afternoon. Highs 61 to 83. East winds up to 25 mph. Chance of rain 70 percent.

Kohala

Today: Mostly cloudy. Breezy. Showers likely in the morning, then scattered showers in the afternoon. Highs 61 to 82. East winds 10 to 25 mph with gusts to 45 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with showers likely. Lows 59 to 64 near the shore to 51 to 60 near 3000 feet. East winds up to 25 mph. Gusts up to 45 mph in the evening. Chance of rain 60 percent.

Friday: Partly sunny. Breezy. Showers likely in the morning, then scattered showers in the afternoon. Highs 61 to 83. East winds up to 25 mph. Chance of rain 70 percent.

South Big Island

Today: Windy. Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 80 near the shore to around 64 near 5000 feet. East winds 10 to 30 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Breezy. Lows around 70 near the shore to around 49 near 5000 feet. Northeast winds 10 to 25 mph.

Friday: Windy. Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 81 near the shore to around 65 near 5000 feet. East winds up to 30 mph. Chance of rain 30 percent.

Puna

Today: Mostly cloudy. Showers in the morning, then scattered showers in the afternoon. Highs 74 to 81 near the shore to around 62 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 80 percent.

Tonight: Mostly cloudy with showers. Lows 60 to 69 near the shore to around 53 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 80 percent.

Friday: Mostly cloudy. Showers in the morning, then showers likely in the afternoon. Highs 74 to 80 near the shore to around 63 at 4000 feet. North winds up to 10 mph shifting to the east in the afternoon. Chance of rain 80 percent.

Waikoloa

Today: Mostly sunny. Windy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 78 to 86 near the shore to 63 to 69 above 4000 feet. Northeast winds up to 30 mph with gusts to 50 mph. Chance of rain 50 percent.

Tonight: Windy. Mostly clear with scattered showers. Lows 65 to 72 near the shore to 47 to 53 above 4000 feet. East winds up to 30 mph shifting to the southeast up to 20 mph after midnight. Chance of rain 40 percent.

Friday: Sunny in the morning then becoming partly sunny. Breezy. Scattered showers. Highs 78 to 86 near the shore to 64 to 69 above 4000 feet. North winds up to 20 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

Locally strong trades will develop today and persist into Friday, focusing clouds and showers mainly over windward and mauka zones. Winds will weaken to breezy and veer to the ESE this weekend. This will favor showers over windward zones at night and potentially over island interiors during the afternoon.

Discussion

Strengthening trades are focusing scattered showers over windward and mauka zones early this morning. Showers over Windward Big Island are considerably more disperse and lighter than several hours ago. However, additional showers are approaching the Big Island, and to a lesser extent Maui, and will arrive during the early to mid-morning hours. Cloud tops over the open water of 11kft or higher offer supporting evidence for the latest modeling which suggests another round of widespread moderate showers is in the offing. As the resident upper trough axis shifts east, a more stable flavor of trades will prevail over the western end of the state while the band of extensive high clouds finally shifts east of the area.
Pressure rises will rapidly build across the north central Pacific basin today day, eventually establishing over the northeast Pacific Friday through the weekend. The increase in the local pressure gradient will be noticeable, and the latest VAD profiles indicate breezy trades have already arrived. Expect continued strengthening of trades with gusty/locally strong trades continuing into Friday. By late Friday, trades will weaken to breezy and veer to the ESE in response to surface high pressure migrating to the northeast Pacific. At the same time, somewhat of a split flow pattern manifests aloft and persists into next week. The latest modeling indicates continued maintenance of the NE Pacific high while a 100+kt upper jet around 25N impinges on the forecast area from the west and elicits a period of mid/upper level troughing late Friday into early next week. A wetter and more unstable trade wind pattern will be possible during this time. However, potential veering of the low- level flow to the ESE or SE threatens to diminish the available moisture, especially over the smaller islands.

Aviation

Strong and gusty trade winds will prevail today into Friday as a surface high passes N of the islands, and AIRMET Sierra for low- level turbulence is posted. Satellite indicates minimal low-level moisture upstream of the smaller islands. While VFR conditions will prevail, a few clouds and showers over windward slopes and coasts will bring ISOL MVFR VIS/CIG in SHRA. Model guidance indicates increasing moisture over windward Big Island later this morning that could produce greater shower coverage, otherwise expect some cloud buildups over leeward Big Island this afternoon.

Marine

A high pressure system north to northeast of the state will slowly drift from west to east, keeping fresh to strong trade winds in the forecast for most coastal waters through Friday. Wind speeds during this period will increase to near gale force conditions in the windier waters and channels near Maui and the Big Island. A Small Craft Advisory (SCA) was expanded this morning to cover almost all Hawaiian coastal waters due to strengthening trade winds. Trades may veer more east-southeasterly by Friday as the high center drifts further eastward and a cold front approaches the region from the northwest. Wind speeds will begin to decrease this weekend, and SCA conditions will decrease in coverage to the typical windier waters and channels near Maui and the Big Island. Combined sea heights will approach 10 feet over most windward waters through Friday.
A northwest swell will continue to build into the western islands this morning. This swell energy will peak today with surf heights remaining well below Surf Advisory criteria. The northwest swell will decline rapidly from Friday into Sunday, with near flat conditions expected along north facing shores by early next week. A period of fresh to strong trades upstream of the islands will keep short period, higher wind wave chop along many northeastern and eastern facing shores into the weekend.
A small background southerly swell will continue through Friday. A slightly larger longer period south swell will begin to build by Friday afternoon with south swell energy peaking on Saturday. This next south swell will build surf heights along south facing shores by a couple of feet into the fun size range through Tuesday.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov