Hilo

Tonight: Occasional showers. Lows 62 to 69 near the shore to 51 to 57 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain near 100 percent.

Friday: Occasional showers. Highs 76 to 82 near the shore to 61 to 66 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain near 100 percent.

Friday Night: Occasional showers. Lows 61 to 68 near the shore to 51 to 56 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain near 100 percent.

Kona

Tonight: Mostly clear. Lows 69 to 74 near the shore to 46 to 51 near 5000 feet. Southeast winds up to 10 mph shifting to the east around 10 mph after midnight.

Friday: Sunny in the morning then becoming partly sunny. Highs 83 to 88 near the shore to around 68 near 5000 feet. East winds around 10 mph shifting to the west in the afternoon.

Friday Night: Mostly clear. Lows 68 to 73 near the shore to 45 to 51 near 5000 feet. East winds around 10 mph.

Waimea

Tonight: Windy. Mostly cloudy with scattered showers. Lows 62 to 71 near the shore to 54 to 62 near 3000 feet. East winds 10 to 30 mph with gusts to 50 mph. Chance of rain 50 percent.

Friday: Windy. Partly sunny with scattered showers. Highs around 78 near the shore to 67 to 77 near 3000 feet. East winds 10 to 30 mph with gusts to 55 mph. Chance of rain 50 percent.

Friday Night: Windy. Mostly cloudy with occasional showers. Lows 62 to 71 near the shore to 54 to 61 near 3000 feet. East winds 10 to 30 mph. Gusts up to 55 mph in the evening. Chance of rain 90 percent.

Kohala

Tonight: Windy. Mostly cloudy with scattered showers. Lows 62 to 71 near the shore to 54 to 62 near 3000 feet. East winds 10 to 30 mph with gusts to 50 mph. Chance of rain 50 percent.

Friday: Windy. Partly sunny with scattered showers. Highs around 78 near the shore to 67 to 77 near 3000 feet. East winds 10 to 30 mph with gusts to 55 mph. Chance of rain 50 percent.

Friday Night: Windy. Mostly cloudy with occasional showers. Lows 62 to 71 near the shore to 54 to 61 near 3000 feet. East winds 10 to 30 mph. Gusts up to 55 mph in the evening. Chance of rain 90 percent.

South Big Island

Tonight: Mostly clear. Windy. Lows around 73 near the shore to around 51 near 5000 feet. East winds 10 to 30 mph.

Friday: Sunny in the morning then becoming partly sunny. Windy. Highs around 85 near the shore to around 67 near 5000 feet. East winds 10 to 30 mph.

Friday Night: Mostly clear. Windy. Lows around 73 near the shore to around 51 near 5000 feet. East winds 15 to 30 mph.

Puna

Tonight: Occasional showers. Lows 62 to 69 near the shore to 51 to 57 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain near 100 percent.

Friday: Occasional showers. Highs 76 to 82 near the shore to 61 to 66 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain near 100 percent.

Friday Night: Occasional showers. Lows 61 to 68 near the shore to 51 to 56 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain near 100 percent.

Waikoloa

Tonight: Mostly clear. Windy. Lows around 72 near the shore to 49 to 54 above 4000 feet. East winds 10 to 30 mph with gusts to 50 mph.

Friday: Sunny and windy. Highs 82 to 89 near the shore to 65 to 71 above 4000 feet. East winds 10 to 30 mph with gusts to 50 mph.

Friday Night: Mostly clear. Breezy. Lows 70 to 75 near the shore to 49 to 54 above 4000 feet. East winds 10 to 25 mph with gusts to 50 mph decreasing to 10 to 15 mph after midnight.

Detailed Forecast

Synopsis

Windy trade winds will persist into the weekend with bands of showers being carried in on the trade wind flow. Showers will be focused over windward and mauka areas, with some of the showers being carried over to leeward areas. A slot of drier air moving in this afternoon through Friday will bring critical fire weather conditions to leeward portions of the state tomorrow. Additional moisture coming in Saturday will boost shower activity once again.

Discussion

GOES-18 analyzes an 0.75″ PWAT airmass on the doorstep of the island chain this afternoon. This airmass coincides roughly with the region of diminished cloud cover and/or low clouds that are stable in appearance on the regional visible loop and will be ushered in on strong trade winds tonight into Friday. Much drier conditions anticipated tomorrow with very limited shower potential over the western end of the state. Exceptions to the rule include windward portions of Maui and the Big Island where upstream moisture will continue to pile up on the windward slopes bringing persistent clouds and rainfall there. Strong 1038mb high pressure maintained by ridging aloft will support windy trades throughout this time. The Wind Advisories for both the low elevations and the Big Island Summits therefore remain in effect with no adjustments needed.
A weakly convergent but well-organized band of trade wind showers is noted on visible imagery about 250 miles N of the islands. This band of showers exists along a subtle area of increased pressure rises within sprawling surface high pressure and has been well- advertised by the guidance. As mid-latitude troughing impinges on resident mid-level ridging and causes it to deamplify and fold eastward late Saturday into Sunday, this corridor of enhanced moisture will be forced through the area Saturday afternoon through Saturday night. This results in higher-than-fnormal confidence in a brief period of wet trades this weekend.
Continued surface pressure falls across the central and northern Pacific will cause trades to weaken during the first half of next week. Drier conditions can be expected as 850mb flow veers to the southeast, steering limited moisture parallel to the island chain.

Aviation

Strong easterly trade winds will decrease slightly overnight then rebuild tomorrow. Blustery trade winds will continue to deliver showery low cloud clusters towards windward slopes and coasts. Occasional spillover showers possible across leeward areas, especially this evening. Occasional periods of MVFR CIGS/VIS within passing showers.
AIRMET Sierra for mountain obscuration remains in effect for north through east sections of Kauai, Oahu, and Windward Big Island. Conditions may improve briefly this evening, but are expected to redevlop overnight.
AIRMET Tango for moderate low-level turbulence over and downwind of the mountains will remain posted until further notice. An AIRMET for moderate upper level turbulence associated with quick- moving trough aloft passing just north of the state has also been issued, but will not likely remain in effect past midnight.

Marine

A strong high pressure system north of the Hawaiian Islands will remain in place over the next few days. Strong and gusty trade winds are expected to blow through Sunday, peaking on Friday and Saturday then slowly decreasing from Sunday onward as a low pressure system weakens the ridge north of the state. A Gale Warning is in effect today through Saturday for the windier waters and channels around Maui and the Big Island. The Small Craft Advisory remains in effect for all remaining coastal waters for the same time period.
The large, long-period northwest (320-330) swell will continue trending down and shift to a more northerly direction (340-360) through Friday. Surf heights will decrease further into the weekend and get minor bumps from small reinforcing northwest swells. Long range models show the potential for a larger north (360) swell by the middle through the latter half of next week.
Rough and choppy surf along east facing shores will hold through the weekend due to the strong trade winds. A High Surf Advisory for exposed east facing shores is in effect through Saturday. Surf heights should gradually decrease next week as trade wind speeds decrease.
Surf heights along south facing shores remains small through the period.
Peak monthly tides are forecast from Nov 15th to 18th. These high tides will combine with elevated seas due to strong trades and rising easterly seas, which may increase coastal inundation impacts for vulnerable locations during early morning high tides. A coastal flood statement is in effect for that time.

Fire weather

In the wake of this morning's band of showers, a dry airmass has begun to push into the area. This airmass will bring dewpoints a few degrees lower than those observed today and will result in tomorrow afternoon's RH values falling to around 45% or slightly lower. Fuels remain dry and windy trades will continue throughout this time. The Fire Weather Watch for Friday has therefore been upgraded to a Red Flag Warning. Additionally, there is low potential for critical fire weather conditions to continue into early Saturday afternoon. A band of showers advancing toward the island chain will then end fire weather concerns no later than Saturday evening.

HFO Watches/Warnings/Advisories

Red Flag Warning from 10 AM to 6 PM HST Friday for Niihau, Kauai South, Kauai Southwest, East Honolulu, Honolulu Metro, Ewa Plain, Waianae Coast, Oahu North Shore, Waianae Mountains, Molokai West, Molokai Leeward South, Lanai Windward, Lanai Leeward, Lanai South, Lanai Mauka, Maui Leeward West, Maui Central Valley North, Maui Central Valley South, South Maui/Upcountry, South Haleakala, Big Island South, Big Island Southeast, Kohala, Big Island Interior.
High Surf Advisory until 6 AM HST Sunday for Olomana, Maui Windward West, Kauai East, Koolau Windward, Molokai Southeast, Windward Haleakala, Kipahulu, South Haleakala, Big Island Southeast, Big Island East, Big Island North.
Wind Advisory until 6 AM HST Saturday for Lanai Mauka, Kahoolawe, Maui Windward West, Maui Leeward West, Kohala, Big Island Interior, Molokai North, Molokai West, Molokai Leeward South, Lanai Windward, Lanai Leeward, Maui Central Valley North, Maui Central Valley South, South Haleakala, Big Island South, Big Island Southeast, Big Island North.
Wind Advisory until 6 AM HST Friday for Big Island Summits.
Small Craft Advisory until 6 AM 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.
Gale Warning until 6 AM HST Sunday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov