Hilo

Tonight: Mostly cloudy. Scattered showers in the evening, then frequent showers after midnight. Lows 62 to 69 near the shore to 52 to 58 at 4000 feet. Northwest winds up to 15 mph. Chance of rain 80 percent.

Wednesday: Cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 78 to 83 near the shore to 63 to 68 at 4000 feet. North winds up to 15 mph. Chance of rain 70 percent.

Wednesday Night: Cloudy with numerous showers. Lows 61 to 68 near the shore to 52 to 58 at 4000 feet. North winds up to 15 mph. Chance of rain 70 percent.

Kona

Tonight: Mostly clear. Isolated showers in the evening. Lows around 71 near the shore to 45 to 52 near 5000 feet. Light winds. Chance of rain 20 percent.

Wednesday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 82 to 87 near the shore to around 68 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Wednesday Night: Partly cloudy with isolated showers. Lows around 72 near the shore to 46 to 52 near 5000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Waimea

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 62 to 71 near the shore to 54 to 62 near 3000 feet. East winds 10 to 25 mph with gusts to 45 mph. Chance of rain 70 percent.

Wednesday: Mostly cloudy. Windy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 63 to 82. East winds 10 to 30 mph. Chance of rain 70 percent.

Wednesday Night: Windy. Mostly cloudy with scattered showers. Lows 62 to 71 near the shore to 55 to 63 near 3000 feet. East winds 10 to 30 mph. Chance of rain 50 percent.

Kohala

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 62 to 71 near the shore to 54 to 62 near 3000 feet. East winds 10 to 25 mph with gusts to 45 mph. Chance of rain 70 percent.

Wednesday: Mostly cloudy. Windy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 63 to 82. East winds 10 to 30 mph. Chance of rain 70 percent.

Wednesday Night: Windy. Mostly cloudy with scattered showers. Lows 62 to 71 near the shore to 55 to 63 near 3000 feet. East winds 10 to 30 mph. Chance of rain 50 percent.

South Big Island

Tonight: Breezy. Partly cloudy with isolated showers. Lows around 73 near the shore to around 51 near 5000 feet. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Wednesday: Mostly sunny in the morning then becoming partly sunny. Windy. Isolated showers. Highs around 86 near the shore to around 68 near 5000 feet. East winds 10 to 20 mph increasing to 10 to 30 mph in the afternoon. Chance of rain 20 percent.

Wednesday Night: Windy. Partly cloudy with isolated showers. Lows around 73 near the shore to around 51 near 5000 feet. East winds 10 to 30 mph. Chance of rain 20 percent.

Puna

Tonight: Mostly cloudy. Scattered showers in the evening, then frequent showers after midnight. Lows 62 to 69 near the shore to 52 to 58 at 4000 feet. Northwest winds up to 15 mph. Chance of rain 80 percent.

Wednesday: Cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 78 to 83 near the shore to 63 to 68 at 4000 feet. North winds up to 15 mph. Chance of rain 70 percent.

Wednesday Night: Cloudy with numerous showers. Lows 61 to 68 near the shore to 52 to 58 at 4000 feet. North winds up to 15 mph. Chance of rain 70 percent.

Waikoloa

Tonight: Mostly clear. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows around 72 near the shore to 49 to 54 above 4000 feet. Southeast winds up to 25 mph with gusts to 45 mph decreasing to up to 15 mph after midnight. Chance of rain 50 percent.

Wednesday: Mostly sunny in the morning then becoming partly sunny. Windy. Isolated showers. Highs 83 to 88 near the shore to 65 to 72 above 4000 feet. Northeast winds up to 30 mph. Chance of rain 20 percent.

Wednesday Night: Partly cloudy. Windy. Scattered showers in the evening, then isolated showers after midnight. Lows around 73 near the shore to 50 to 55 above 4000 feet. Southeast winds up to 30 mph decreasing to up to 20 mph after midnight. Chance of rain 40 percent.

Detailed Forecast

Synopsis

Breezy trade winds will strengthen and become windy through the end of the week. Showers will focus along windward mauka exposures, reaching leeward sides of the smaller islands as winds strengthen.

Discussion

High pressure systems far north and northeast of Hawaii are separated by a cold front across the northeast Pacific. The northern one is a strong 1034 mb high and resulting in robust trade winds across the islands today. 00Z soundings at Hilo and Lihue show a strong 7000 ft inversion in place across the area. Visible satellite and radar show a band of showery clouds over and just upstream of Kauai to Maui this afternoon. Expect light and quickly passing showers mainly for windward slopes of these islands late tonight into Wednesday, with isolated showers leeward. Trade wind showers are likely to increasing again Wednesday night into Thursday.
The high to the north will take over while the front weakens and is pushed southward by the northern high building behind it. Trade winds speeds will begin to increase by Wednesday and continue strengthening through the end of the week. Winds are forecast to peak Friday through Saturday with some portions of the state reaching advisory levels as early as Thursday. Peak winds are in conjunction with the arrival and departure of the remains of the dissipated cold front reaching the islands (the front mentioned earlier). An increase in cloud cover and showers is expected as this feature passes through with both windward and leeward sides of the islands receiving rainfall. Wind speeds will slowly taper down Sunday into Monday (but still remain fairly breezy) with continuing showers focusing windward and mauka.

Aviation

Breezy easterly trades will gradually strengthen through Wednesday with strong and gusty trades expected on Wednesday. Clouds and showers will favor windward and mauka areas with an uptick of showers expected tonight. Brief periods with MVFR CIGS/VSBYS are possible in passing showers. Otherwise, VFR conditions will prevail.
AIRMET Tango for moderate low-level turbulence will persist over and downwind of all island terrain.
AIRMET Sierra will likely be needed later tonight for many windward and mountain areas due to the increase of showers.

Marine

A broad ridge of high pressure north of the islands will strengthen through the rest of the week, translating to strong trades tonight into Thursday and possibly reaching gale-force Friday into the weekend. The Small Craft Advisory has been expanded to include all coastal waters due to the trades strengthening and seas become elevated from those winds and an incoming northwest swell tonight. A Gale Watch may be needed tonight or Wednesday in anticipation of winds speeds increasing further for the second half of the week.
Existing medium to long-period northwest (320 degrees) swell energy will be reinforced by a larger, long-period northwest (320-330) swell later tonight. This swell is forecast to peak well above advisory levels threshold for north and west facing shores Wednesday, potentially nearing High Surf Warning thresholds late Wednesday, before fading Thursday. This swell will mix with a small, long- period north-northwest (340-350) swell that will also peak tonight into Wednesday. A High Surf Advisory has been issued for north and west facing shores of Niihau, Kauai, Oahu, and Molokai, as well as north facing shores of Maui, going into effect at 6 AM HST Wednesday.
Rough and choppy surf along east facing shores will gradually become more elevated during the second half of the week as trades become stronger locally and upstream of the islands. Surf along east facing shores is expected to build to the advisory level Thursday into Friday, then hold into the weekend.
Surf along south facing shores remains small through the period, except for a small bump expected Wednesday.
Peak monthly tides are forecast from Nov 14th to 18th. These high tides will combine with elevated seas due to strong trades and slowly fading northwest/north swells to exacerbate coastal inundation impacts, particularly for vulnerable locations during early morning high tides.

Fire weather

Trade wind speeds are forecast to exceed sustained 20 mph at Honolulu airport Friday and Saturday, with higher speeds in more exposed areas around the state. It is also possible for winds to also reach 20 mph on Thursday while ramping up, and on Sunday while trending down. KBDI is currently 672 today. The limiting factor will be relative humidity, which is expected to stay in the upper 40s to lower 50s as moisture from a dissipated front reaches the islands Friday night. While a Fire Weather Watch or Red Flag Warning is not anticipated at this time, conditions may come close on Friday afternoon. Will be monitoring for any changes in this forecast in the coming days.

HFO Watches/Warnings/Advisories

High Surf Advisory from 6 AM Wednesday to 6 PM HST Thursday for north and west facing shores of Niihau, Kauai, Oahu, Molokai and for north facing shores of Maui.
Small Craft Advisory until 6 AM HST Thursday for all Hawaiian waters,

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Data Courtesy of NOAA.gov