West Kaua’i

Tonight: Mostly cloudy. Lows around 75 near the shore to around 66 above 3000 feet. Northeast winds up to 15 mph.

Thursday: Partly sunny. Highs 86 to 91 near the shore to around 78 above 3000 feet. Northeast winds up to 15 mph.

Thursday Night: Partly cloudy in the evening, then mostly cloudy with isolated showers after midnight. Lows around 75 near the shore to around 66 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

South Kaua’i

Tonight: Breezy. Mostly cloudy with isolated showers. Lows 72 to 78. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Thursday: Breezy. Partly sunny with isolated showers. Highs 80 to 90. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Thursday Night: Mostly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows 72 to 78. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Kaua’i Mountains

Tonight: Mostly cloudy with scattered showers. Lows around 71 in the valleys to around 62 above 4000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs 70 to 84. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Thursday Night: Mostly cloudy. Breezy. Scattered showers in the evening, then scattered showers and isolated thunderstorms after midnight. Locally heavy rainfall possible after midnight. Lows around 70 in the valleys to around 62 above 4000 feet. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

North Kaua’i

Tonight: Mostly cloudy with isolated showers. Lows 66 to 76. East winds 10 to 15 mph. Chance of rain 20 percent.

Thursday: Partly sunny with isolated showers. Highs 71 to 88. East winds 10 to 15 mph. Chance of rain 20 percent.

Thursday Night: Mostly cloudy with scattered showers. Lows 66 to 76. East winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 68 to 77. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Thursday: Partly sunny with scattered showers. Highs 78 to 86. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Thursday Night: Mostly cloudy. Breezy. Scattered showers in the evening, then scattered showers and isolated thunderstorms after midnight. Lows 68 to 77. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Nolo has formed south of the Big Island and is forecast to move north toward the Big Island Friday and Saturday as a hurricane, bringing potentially damaging winds and heavy flooding rainfall. A Hurricane Watch is in effect for the Big Island and surrounding waters. In addition, a Flood Watch is in effect for Maui County and the Big Island through Saturday. Uncertainty in the track of the hurricane remains higher than normal. The latest forecast calls for Nolo to be close enough to bring a threat for significant impacts through the weekend.

Discussion

Radar and satellite show numerous showers over Big Island, along with a large band of showers to its south which is being heavily influenced by Nolo. Elsewhere, conditions are dry. Skies were mostly cloudy on Big Island and in windward/mauka areas on other islands. Winds were averaging 10-20 mph, with gusts 30-35 mph in the usual gusty places.
The latest update on Nolo has it located near 14.7N and 155.9W (about 350 miles south of Hilo) with maximum winds of 45 mph. It was moving WNW (285 degrees) at 6 mph. The forecast calls for it to move generally N tonight, then NNE Thursday through Thursday night. It is forecast to turn to the NW and then W Friday into Saturday. There is uncertainty on exactly when those Friday into Saturday turns will occur, and therefore how close it will get to the Big Island.
The forecast rainfall on Big Island remains 20-30 inches, with isolated amounts to 35 inches. On Maui, we expect 10-15 inches, with isolated amounts to 15 inches. Winds will begin to increase significantly Thursday night into Friday, and wind advisories or warnings will likely be needed outside of the Hurricane Warning area.
The current forecast has only minor changes. We slightly increased the rainfall totals on Maui and the Big Island, increased the chance of rain in several areas, and made small edits to winds. Unless/until the track changes significantly, the forecast is rather stable for now.

Aviation

Breezy trade winds continue into Thursday. Gusts to around 35 knots are expected this afternoon evening with winds decreasing slightly overnight. Shower chances increase and MVFR conditions become more widespread across the Big Island today with some potential for isolated thunderstorm activity due to Tropical Storm Nolo to our south. Shower chances increase northwards across the islands through Molokai tonight into tomorrow. Periods of MVFR ceilings and visibilities are possible as heavier showers move across the islands. Rain, moderate to heavy at times, will continue into the weekend. See main discussion for more info on Tropical Storm Nolo.
AIRMET Sierra is in effect for mountain obscuration and may continue into tomorrow morning.
AIRMET Tango is in effect for low level turbulence downwind of island terrain.

Marine

Main changes with the afternoon package are an expansion of the Small Craft Advisory (SCA) for a combination of winds and seas over the next couple of days. The SCA continues for typical windier areas tonight, and expands to the central waters tomorrow, and then to Kauai waters Friday. Friday morning the waters near the Big Island transition from a SCA to the Hurricane Watch for Tropical Storm Nolo.
Tropical Storm Nolo is moving slowly northward towards the islands, and will bring increasing swell, winds and rainfall beginning Thursday. While waters near the Big Island are under a Hurricane Watch now, additional waters may need to be added to tropical watches or warnings, depending on the exact track of Nolo is determined with future model runs. Nolo is currently expected to continue on a northward trend, before a turn to the west, but is expected to impact the coastal waters through the weekend.
The current south-southwest swell continue to fade, and a moderate southwest swell will build in Friday, and last into the weekend, with surf peaking near advisory levels. Tropical Storm Nolo is expected to strengthen, and will likely produce a southerly swell that will bring large and rough surf particularly to the south facing shores of the Big Island.
A new small northwest swell will fill in this weekend keeping surf slightly elevated along north and west facing shores. East facing shores will maintain rough, short period wind waves generated from the breezy trade winds.

Fire weather

Winds will steadily strengthen over the next several days as Nolo moves nearer, creating moderate fire weather conditions mainly over drier leeward areas. Rainfall will increase each day through Saturday, mitigating to some extent the stronger winds. The inversion will not be present over the eastern end of the state through this weekend.

HFO Watches/Warnings/Advisories

Flood Watch through Saturday afternoon for Big Island East, Big Island Interior, Big Island North, Big Island South, Big Island Southeast, Big Island Summits, Haleakala Summit, Kahoolawe, Kipahulu, Kohala, Kona, Lanai Leeward, Lanai Mauka, Lanai South, Lanai Windward, Maui Central Valley North, Maui Central Valley South, Maui Leeward West, Maui Windward West, Molokai Leeward South, Molokai North, Molokai Southeast, Molokai West, Molokai Windward, South Haleakala, South Maui/Upcountry, Windward Haleakala.
Hurricane Watch for Big Island East, Big Island Interior, Big Island North, Big Island South, Big Island Southeast, Big Island Summits, Kohala, Kona.
Hurricane Watch for Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters, Big Island Windward Waters.
Small Craft Advisory from 6 AM Friday to 6 PM HST Saturday for Kauai Leeward Waters, Kauai Northwest Waters, Kauai Windward Waters.
Small Craft Advisory from 6 AM Thursday to 6 PM HST Saturday for Kaiwi Channel, Kauai Channel, Maui County Leeward Waters, Maui County Windward Waters, Oahu Leeward Waters, Oahu Windward Waters.
Small Craft Advisory until 6 PM HST Saturday for Maalaea Bay, Pailolo Channel.
Small Craft Advisory until 6 AM HST Friday for Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov