Photo Credit: James Grenz

Hilo

Today: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 82 near the shore to 67 to 72 at 4000 feet. North winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 70 percent.

Tonight: Mostly cloudy with numerous showers. Lows around 70 near the shore to around 57 at 4000 feet. North winds up to 15 mph. Chance of rain 70 percent.

Friday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to 68 to 73 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 70 percent.

Kona

Today: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 80 to 86 near the shore to around 67 near 5000 feet. West winds up to 10 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows around 75 near the shore to around 58 near 5000 feet. Light winds. Chance of rain 20 percent.

Friday: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 81 to 86 near the shore to around 68 near 5000 feet. West winds up to 10 mph. Chance of rain 40 percent.

Waimea

Today: Breezy. Partly sunny with scattered showers. Highs around 80 near the shore to 67 to 78 near 3000 feet. East winds 10 to 25 mph with gusts to 45 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 70 near the shore to 58 to 64 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Friday: Breezy. Partly sunny with scattered showers. Highs around 81 near the shore to 68 to 78 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Kohala

Today: Breezy. Partly sunny with scattered showers. Highs around 80 near the shore to 67 to 78 near 3000 feet. East winds 10 to 25 mph with gusts to 45 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 70 near the shore to 58 to 64 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Friday: Breezy. Partly sunny with scattered showers. Highs around 81 near the shore to 68 to 78 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

South Big Island

Today: Breezy. Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 85 near the shore to around 72 near 5000 feet. East winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows 70 to 75 near the shore to around 55 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Friday: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs around 85 near the shore to around 72 near 5000 feet. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 20 percent.

Puna

Today: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 82 near the shore to 67 to 72 at 4000 feet. North winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 70 percent.

Tonight: Mostly cloudy with numerous showers. Lows around 70 near the shore to around 57 at 4000 feet. North winds up to 15 mph. Chance of rain 70 percent.

Friday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to 68 to 73 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 70 percent.

Waikoloa

Today: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs around 85 near the shore to 68 to 74 above 4000 feet. Northeast winds up to 25 mph with gusts to 45 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening. Lows around 75 near the shore to 55 to 60 above 4000 feet. East winds up to 25 mph. Chance of rain 20 percent.

Friday: Sunny and breezy. Isolated showers in the afternoon. Highs around 85 near the shore to 69 to 75 above 4000 feet. Northeast winds up to 25 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Breezy trades will continue to focus showers and lower clouds over windward and mauka areas this morning, before diminishing in areal coverage this afternoon. Otherwise, the trade wind pattern in place across the islands will continue through Friday. The remnants of Hurricane Darby will pass south of the Big Island this weekend, generating a period of locally strong trades and enhanced showers across windward areas, particularly over the eastern end of the state.

Discussion

The easterly trade wind pattern in place across the islands this morning will persist through the remainder of the work week. This pattern will continue to generate showers and lower clouds across mainly windward and mauka areas through Friday night. Current radar and satellite trends continue to show showers affecting windward locations and in channels between islands this morning, especially in the convergent low level flow into the central islands. However, this area of showers is expected to diminish in areal coverage again this afternoon as afternoon mixing develops. Additionally, the latest model soundings and cross section data, shows relatively stable conditions lingering over the islands through Friday which will hinder rainfall rates and overall rainfall amounts across the region.
Otherwise the latest forecast trends continue to show Hurricane Darby (which is around 1100 miles E of Hilo) moving toward the islands, with the remnants of Darby still expected to pass south of the Big Island Saturday. There still remains some questions with the exact track of this approaching tropical system, however the northern periphery of the associated moisture field is modeled to influence mainly the eastern islands Saturday through early Sunday, increasing the deep layered moisture potential and heavy rainfall for windward sections of the Big Island and possibly Maui. The airmass in place across the region in advance of the remnants of Darby is expected to initially be relatively stable with drier mid and upper levels likely limiting convection and rainfall rates. However, cross section data shows deeper layer moisture quickly expanding across the Big Island and Maui Saturday night and early Sunday in response to the systems currently forecast closest approach. This could increase the threat for potentially heavy rainfall late Friday night through Saturday. Trades will also become locally strong early this weekend with a wind advisory for the typical windier locales in Maui County and the Big Island potentially in play depending on the exact track.
A much drier and stable airmass will then develop across the islands on Sunday and Monday, as drier air moves across the islands from the east on the back side of the exiting remnant tropical system.

Aviation

High pressure north of the state will keep breezy trade winds in place through tonight. Low clouds and showers will favor windward and mauka areas, with some MVFR cigs/vsbys possible at times. A few showers may drift leeward occasionally, but VFR conditions should prevail in these areas.
AIRMET Tango remains in effect for moderate low level turbulence over and downwind of the terrain of all islands. This AIRMET will likely continue through tonight.
AIRMET Sierra remains in effect for mountain obscuration over windward sections of most islands. Conditions should improve later this morning over the smaller islands, but may continue through much of the day for the Big Island.

Marine

A high pressure system north of the region will keep fresh to strong trade winds in the forecast through much of next week. Wind speeds may briefly strengthen to near-gale force in the typical windy waters near Maui and the Big Island.
The Small Craft Advisory was expanded to include most Hawaiian Coastal Waters east of the Kaiwi Channel, except the Big Island Windward Waters zone. A slight decrease in trade wind speeds may develop by Friday morning, decreasing the SCA coverage back to the typical windier waters and channels around Maui and the Big Island.
Hurricane Darby has moved into the Central Pacific basin and will continue to track westward over the next few days. Darby is forecast to weaken as it approaches the Hawaiian Islands, becoming a remnant low as it enters the far southeast offshore waters by Saturday morning. Expect increasing showers and strengthening winds for the southern offshore and coastal waters near the Big Island as the remnants of Darby pass south of the state on Saturday.
South shore surf heights will remain well above average through the weekend as two large and long period south swells move through the region. The first of these large south swells will continue to push surf heights above High Surf Advisory (HSA) levels through this evening. Surf heights will then ease a little from tonight into Friday, before another larger and longer period (20-22 sec) south swell moves into the region from late Friday through Sunday. Peak surf heights along south facing shores with this second swell will easily exceed HSA criteria (10 foot faces) by Friday night, with surf heights reaching High Surf Warning levels (15 foot faces) on Saturday and Sunday. South swell energy will gradually decrease through the first half of next week.
Surf along east facing shores will remain elevated and rough into early next week. Swells generated by Darby are expected to add to the mix, with the longer period energy starting to show up this afternoon, and the peak on Saturday. This swell will likely be highest along east facing shores of the Big Island, where a High Surf Advisory may be required for this weekend. Surf heights along north facing shores will remain flat through the week.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for Niihau, Kauai Leeward, Waianae Coast, Kahoolawe, Maui Leeward West, Kona, Kauai South, East Honolulu, Honolulu Metro, Ewa Plain, Molokai Southeast, Molokai Leeward South, Lanai Leeward, Lanai South, Maui Central Valley South, Kipahulu, South Maui/Upcountry, South Haleakala, Big Island South, Big Island Southeast.
Small Craft Advisory until 7 PM HST Sunday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 PM HST Saturday for Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters.

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Data Courtesy of NOAA.gov