Photo Credit: Jason Weingardt

West Kaua’i

Today: Mostly sunny. Isolated showers in the afternoon. Highs around 88 near the shore to around 76 above 3000 feet. Northeast winds up to 10 mph shifting to the southwest in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 70 to 75 near the shore to around 61 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs around 89 near the shore to around 77 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny with scattered showers. Highs around 85. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Tonight: Partly cloudy with scattered showers. Lows 68 to 74. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Mostly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 86. East winds 10 to 15 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 75 to 82 in the valleys to around 66 above 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 61 to 66 in the valleys to around 56 above 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Tuesday: Partly sunny with numerous showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs 76 to 83 in the valleys to around 67 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

North Kaua’i

Today: Mostly sunny with scattered showers. Highs 78 to 87. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers. Lows 64 to 74. East winds up to 15 mph shifting to the southeast after midnight. Chance of rain 50 percent.

Tuesday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 79 to 88. East winds up to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 78 to 86. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 62 to 76. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 79 to 87. East winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Moderate to locally breezy conditions will prevail during the next couple of days, with showers favoring windward and mauka areas. The trades will increase to breezy levels Wednesday through late next week. Typical trade wind weather will prevail through Thursday, before more showery conditions develop Thursday night and Friday. It could get particularly windy and wet across portions of the state over the weekend, depending on the track and degree of development of Invest 90E, well southeast of the island chain.

Discussion

Currently at the surface, a trough of low pressure is located around 750 miles north-northwest of Honolulu, while a 1030 mb high is positioned around 1500 miles north of the islands. Meanwhile, an area of low pressure (Invest 90E) is located around 1300 miles east-southeast of Hilo. Moderate to locally breezy trade winds remain in place across the state this morning. Infrared satellite imagery shows partly to mostly cloudy conditions across the state, with cloud coverage the highest over windward sections of Oahu and Maui County. Radar imagery shows most of the shower activity moving into windward sections of Maui County and just upstream of Oahu, with sparse shower coverage elsewhere. Main short term focus revolves around trade wind trends and rain chances, with all long term attention centered on the potential development of Invest 90E.
Moderate to locally breezy trade winds will remain in place during the next couple days, with the strongest gradient associated with the high to the north remaining cut off by a series of troughs in between the high and the islands. The troughs north of the state will dampen out around mid week, allowing the strong high to the north to ramp the trades up to breezy levels Wednesday through late next week. Depending on the eventual track and degree of development of what is now Invest 90E, it could get particularly windy across the islands over the weekend.
As for the remaining weather details, a band of higher moisture will bring increased shower activity to windward sections of Oahu and Maui County this morning, with fewer showers expected across Kauai and the Big Island. Fairly typical trade wind weather will then prevail this afternoon through Thursday, with showers favoring windward and mauka areas and a stray shower reaching leeward communities from time to time. It looks to get a bit more showery Thursday night through Friday night as inversion heights rise and some deeper moisture moves in from the east.
Quite a bit of uncertainty remains in the forecast for next weekend as all will depend on the track and potential development of Invest 90E. Both the National Hurricane Center and the Central Pacific Hurricane Center are closely monitoring Invest 90E well east-southeast of the island chain, so stay tuned for updates over the next several days as details begin to become more clear.

Aviation

Satellite and radar imagery this morning continues to show bands of low clouds and showers moving into windward and mountain areas. The largest of these low level cloud bands continues to drift into windward Maui, Molokai, and Oahu; resulting in periods of low ceilings. Trade wind showers will decrease during the day and then increase in coverage later tonight. Moderate to locally breezy trade winds remain in the forecast.
AIRMET Sierra remains in effect for tempo mountain obscuration along north and east sections of Oahu, Molokai and Maui. This AIRMET will decrease in coverage around 22Z today.
AIRMET Tango remains in effect for moderate low level turbulence over and immediately downstream of island mountains. This AIRMET will likely be cancelled later this morning as wind speeds ease a bit.

Marine

Fresh to strong easterly trade winds will continue through Tuesday, then increase to strong levels for most waters beginning around Wednesday as high pressure builds to the north. The Small Craft Advisory in place for the typical windier waters/channels around Maui County and the Big Island will persist for much of the week, likely becoming expanded to most waters Wednesday through the second half. The National Hurricane Center in Miami, Florida is forecasting a high chance of tropical cyclone development in the eastern Pacific over the next couple of days, that could enter the Central Pacific well southeast of the Hawaiian waters later in the week. Later forecasts across the Hawaiian waters will highly depend on how this development evolves over the next several days.
Surf along south facing shores will continue to climb through the day as a fresh, long-period south-southwest swell steadily builds. Observations at the offshore buoys (NDBC 51004/51003) reflect this upward trend with energy picking up in the 15 to 19 second bands this morning. Based on the peak at the Samoa buoy back on Thursday, expect a local peak sometime between later today and Tuesday, likely coming in below the advisory level. A downward trend will follow through the second half of the week.
Surf along north and west facing shores will trend up around Wednesday as a long-period west-northwest swell arrives from former Typhoon Ampil tracking northeastward over the far northwest Pacific. This should peak Wednesday through Thursday, then ease by next weekend.
Surf along east facing shores will remain small through Tuesday, then trend up Wednesday through the rest of the week as the trades increase locally and far east of the islands.
Minor tidal flooding will remain possible this afternoon due to water levels running higher than predicted. A downward trend is expected through the rest of the week.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov