Hilo

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 61 to 70 near the shore to 51 to 56 at 4000 feet. North winds up to 15 mph. Chance of rain 70 percent.

Wednesday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 79 near the shore to around 66 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Wednesday Night: Mostly cloudy with numerous showers. Lows 61 to 69 near the shore to 52 to 57 at 4000 feet. North winds up to 15 mph. Chance of rain 70 percent.

Kona

Tonight: Partly cloudy. Haze. Lows 64 to 73 near the shore to 50 to 55 near 5000 feet. Light winds.

Wednesday: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Haze through the day. Highs 83 to 88 near the shore to around 68 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Wednesday Night: Partly cloudy. Isolated showers in the evening. Haze through the night. Lows 65 to 74 near the shore to 51 to 56 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Scattered showers. Lows 62 to 71 near the shore to 56 to 63 near 3000 feet. East winds 10 to 25 mph decreasing to up to 25 mph after midnight. Chance of rain 50 percent.

Wednesday: Breezy. Partly sunny with scattered showers. Highs around 79 near the shore to 69 to 77 near 3000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Gusts up to 40 mph. Chance of rain 50 percent.

Wednesday Night: Breezy. Mostly cloudy with scattered showers. Lows 62 to 71 near the shore to 56 to 63 near 3000 feet. East winds 10 to 20 mph decreasing to up to 20 mph after midnight. Chance of rain 50 percent.

Kohala

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Scattered showers. Lows 62 to 71 near the shore to 56 to 63 near 3000 feet. East winds 10 to 25 mph decreasing to up to 25 mph after midnight. Chance of rain 50 percent.

Wednesday: Breezy. Partly sunny with scattered showers. Highs around 79 near the shore to 69 to 77 near 3000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Gusts up to 40 mph. Chance of rain 50 percent.

Wednesday Night: Breezy. Mostly cloudy with scattered showers. Lows 62 to 71 near the shore to 56 to 63 near 3000 feet. East winds 10 to 20 mph decreasing to up to 20 mph after midnight. Chance of rain 50 percent.

South Big Island

Tonight: Partly cloudy. Breezy and haze. Lows around 74 near the shore to around 56 near 5000 feet. East winds up to 25 mph shifting to the northeast 10 to 25 mph after midnight.

Wednesday: Mostly sunny. Breezy. Haze through the day. Isolated showers in the afternoon. Highs around 86 near the shore to around 69 near 5000 feet. East winds 10 to 25 mph decreasing to up to 25 mph in the afternoon. Chance of rain 20 percent.

Wednesday Night: Partly cloudy. Breezy. Isolated showers in the evening. Haze through the night. Lows around 74 near the shore to around 57 near 5000 feet. East winds up to 25 mph shifting to the northeast 10 to 20 mph after midnight. Chance of rain 20 percent.

Puna

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 61 to 70 near the shore to 51 to 56 at 4000 feet. North winds up to 15 mph. Chance of rain 70 percent.

Wednesday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 79 near the shore to around 66 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Wednesday Night: Mostly cloudy with numerous showers. Lows 61 to 69 near the shore to 52 to 57 at 4000 feet. North winds up to 15 mph. Chance of rain 70 percent.

Waikoloa

Tonight: Mostly clear. Breezy. Lows 66 to 73 near the shore to 51 to 56 above 4000 feet. East winds up to 25 mph.

Wednesday: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 82 to 88 near the shore to around 69 above 4000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Wednesday Night: Partly cloudy. Breezy. Lows 66 to 73 near the shore to around 54 above 4000 feet. East winds up to 20 mph.

Detailed Forecast

Synopsis

Breezy east northeasterly trade winds will remain through the week and could ease slightly this weekend and become more easterly. Showers will favor windward and mountain areas, as well as the night time and early morning hours. Late this week into the weekend, an upper-level low could bring an uptick in trade wind shower coverage.

Discussion

At the surface, a dominate high pressure system resides far to the north of the Hawaiian islands, and will keep east to eastnortheast trade winds blowing through the weekend and into next week. Most of the rain this evening has fallen over Kauai, with some showers upstream approaching the other islands. Showers will be pushed over the typical windward and mountain areas, favoring the night time and early morning hours.
By Friday through the weekend, models continue to show a mid to upper- level cutoff low moving over the region, bringing cooler temperatures aloft and increasing instability. Precipitable water values at that time are expected to climb to 1.5 to almost 2 inches over the eastern end of the state as moisture is drawn up from the south. Its hard to know at this moment how much rain could fall, as some dry air and ridging could linger, inhibiting showers. But localized heavy showers especially over the mountain ranges look like a possibility at this time. This upper low is also expected to usher in muggier conditions as dew points climb into the lower 70s and the extra moisture could linger into early next week.

Aviation

High pressure far north of the islands will maintain a breezy trade wind pattern through at least Wednesday. Mid-level ridging will help to limit shower activity with a stable airmass in place.
Limited showers will continue to be carried in on the trade wind flow. At times these showers could bring some mountain obscuration to various islands, mostly at night and during the morning hours. Otherwise, VFR conditions are expected to prevail.
AIRMET Tango remains in effect for mechanical turbulence to the lee of the mountains due to the breezy trade winds. Expect this to remain in place through at least Wednesday

Marine

A slow eastern-moving area of high pressure north of the islands will maintain generally moderate to locally strong Small Craft Advisory level trade wind winds through Thursday. An upper level low dropping south in the wake of the east exiting high will increase north and west water shower chances from Friday into the weekend.
A small short to medium period northwest (330 degree) swell will slowly decline through tonight. A larger long period northwest swell will arrive late Wednesday and will peak on Thursday. This will push north-facing surf to near or slight over head high levels.
Very small, medium period south swell will occur through the remainder of week. A long period south bump arrives Saturday and this will produce slightly elevated south-facing shore surf. Enhanced trades will maintain above seasonable east-facing shore wind wave chop the next several days.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Wednesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov