Photo Credit: Tyler Rooke

West Side

Today: Scattered showers. Partly sunny, with a high near 81. East northeast wind 7 to 10 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 71. East northeast wind 9 to 13 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Wednesday: Isolated showers. Partly sunny, with a high near 81. Breezy, with an east northeast wind around 16 mph, with gusts as high as 22 mph. Chance of precipitation is 20%.

South Side

Today: Scattered showers. Partly sunny, with a high near 81. Northeast wind 5 to 7 mph becoming light and variable in the afternoon. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 69. Northeast wind around 6 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Isolated showers. Partly sunny, with a high near 81. Northeast wind 5 to 7 mph becoming light and variable in the morning. Chance of precipitation is 20%.

North Shore

Today: Scattered showers. Partly sunny, with a high near 79. Windy, with an east wind around 26 mph, with gusts as high as 38 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 70. Windy, with an east wind around 26 mph, with gusts as high as 38 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Wednesday: Scattered showers. Partly sunny, with a high near 79. Windy, with an east wind around 26 mph, with gusts as high as 38 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Central Maui

Today: Scattered showers. Partly sunny, with a high near 80. Windy, with an east northeast wind 17 to 24 mph, with gusts as high as 34 mph. Chance of precipitation is 40%. New precipitation amounts between a quarter and half of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 68. Windy, with an east northeast wind 20 to 24 mph, with gusts as high as 34 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Wednesday: Scattered showers, mainly before 7am. Partly sunny, with a high near 80. Windy, with an east northeast wind 21 to 25 mph, with gusts as high as 36 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Upcountry

Today: Isolated showers. Partly sunny, with a high near 69. East southeast wind 5 to 7 mph becoming calm in the morning. Chance of precipitation is 20%.

Tonight: Isolated showers. Mostly cloudy, with a low around 60. Calm wind becoming east southeast around 6 mph in the evening. Chance of precipitation is 20%.

Wednesday: Isolated showers before 7am. Partly sunny, with a high near 69. East southeast wind 5 to 7 mph becoming calm in the morning. Chance of precipitation is 20%.

East Maui

Today: Showers. High near 75. Breezy, with an east wind 14 to 17 mph, with gusts as high as 24 mph. Chance of precipitation is 80%. New precipitation amounts between a quarter and half of an inch possible.

Tonight: Showers. Low around 71. Breezy, with an east wind around 15 mph, with gusts as high as 21 mph. Chance of precipitation is 90%. New precipitation amounts between a quarter and half of an inch possible.

Wednesday: Showers likely. Cloudy, with a high near 75. Breezy, with an east wind 15 to 17 mph, with gusts as high as 24 mph. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

Lanai City

Today: Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 72. Breezy, with a northeast wind 11 to 15 mph, with gusts as high as 21 mph. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Tonight: Scattered showers. Mostly cloudy, with a low around 66. Northeast wind 9 to 14 mph, with gusts as high as 18 mph. Chance of precipitation is 50%. New precipitation amounts between a tenth and quarter of an inch possible.

Wednesday: Scattered showers. Partly sunny, with a high near 72. Breezy, with an east northeast wind 14 to 18 mph, with gusts as high as 25 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Kaunakakai

Today: Scattered showers and thunderstorms. Partly sunny, with a high near 81. Breezy, with an east wind 17 to 20 mph, with gusts as high as 28 mph. Chance of precipitation is 40%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Tonight: Scattered showers. Mostly cloudy, with a low around 73. Breezy, with an east wind 16 to 20 mph, with gusts as high as 28 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Wednesday: Scattered showers. Partly sunny, with a high near 81. Breezy, with an east wind 17 to 20 mph, with gusts as high as 28 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Detailed Forecast

Synopsis

A strong high pressure system far north of the islands and a disturbance passing south of Kauai this morning will keep moderate to breezy easterly trade winds, wet weather with heavy showers, thunderstorms, and the potential for flash flooding in the forecast through this afternoon. The flooding threat will likely decrease by tonight with more stable weather conditions moving into the region. Shower trends statewide will decrease through Wednesday. Breezy trade winds will focus most of the shower activity over windward and mountain areas through the weekend. An increase in shower activity may develop statewide from Friday night into Saturday.

Discussion

A strong high pressure system far north of the state will produce breezy easterly trade winds across the state into the weekend. An upper level low passing south of Kauai this morning will continue to slowly drift northwestward, moving away from the islands on Wednesday. Unstable air around this low will combine forces with the breezy trade winds to produce numerous rain showers, heavy at times, across the state. Local radar imagery this morning shows continued moderate showers moving into the eastern half of the Big Island. An elevated flash flood threat will continue across the state today and a Flash Flood Watch remains in effect for all Hawaiian Islands until 6 PM HST this evening.
Decreasing rainfall trends will return to the region starting tonight, with diminishing threats for heavy showers through Wednesday as the upper low continues to drift northwestward away from the island chain, and a stable upper level ridge builds in over the region. The strong high pressure system lingering far north of the state will keep breezy easterly trade winds in the forecast through the weekend. Passing trade wind showers will favor windward and mountain areas this week with an increase in shower activity possible from Friday night into Saturday.
Short range global model guidance remains in good agreement with this decreasing rainfall trend as an upper level ridge keeps more stable weather conditions in place through Thursday. Medium range guidance for this weekend are trending towards more unsettled showers mainly affecting windward and mountain areas.

Aviation

Strong ESE flow combined with abundant moisture is bringing visibility concerns due to clouds and SHRA. Areas of MVFR and IFR will remain today with isolated LIFR in the heaviest pockets of rain.
AIRMET Sierra remains in effect for mountain obscuration for most islands.
AIRMET Tango remains in effect for low-level mechanical turb and strong surface winds.
AIRMET Zulu remains in effect for light to moderate rime icing.

Marine

The early Tuesday morning weather map shows a new 1034 mb surface high located far N of the islands moving southward. It will dissipate a good distance north of the islands on Thursday. A new surface high follows in over the weekend. This series of highs will help maintain breezy conditions through the rest of the week. Eventually, the breezy trades will trim back to the typical locally breezy picture late in the weekend.
The current wind has a slight south of east component, making it not your true trade winds. A pair of surface troughs, one 620 nm NW of Kauai and the other, some 280 nm SW of Kauai, is responsible for this wind situation. The one furthest NW will continue to weaken, while the second one heads further W, away from the islands. This action will cause the winds to become east today, which is considered trade winds.
The strong and breezy winds generated locally and upwind of the islands have resulted in very rough and elevated seas and high surf along east facing shores. A Small Craft Advisory (SCA) is in place for all near- shore marine zones through 6 pm HST Wednesday. A High Surf Advisory (HSA) has been extended through Wednesday night to 6 am HST Thursday for the elevated surf along the east facing shores. The fetch area of this trade wind swell will be back to normal heights later in the week, so the surf, although in the advisory range, will be smaller.
The current NW swell will continue to trend down through Wednesday. Then a set of WNW to NW swells arrives Thursday night, peak Friday night and Saturday, raising the surf along the north and west facing shores to near advisory levels. After a busy first few weeks of January where we saw some very very large northwest swells. these large swell producing storm systems will be absent for a while. So for early next week, we expect small to moderate size swells ranging from the NW to NNE directions.
A surface low is forecast to drop south along the Pacific Northwest in the next 24 hours before dissipating off the California coast on Wednesday and Wednesday night. This low has already generated a N to NNE pulse toward the islands. This swell will give boost to the surf along exposed north and some east facing shores. This swell is slated to arrive Thursday, peak Friday/Friday night, then gradually subside through the weekend.
Surf along south facing shores will trend up through midweek, as an out-of-season Tasman source arrives. Surf should drop and return to normal levels through the second half of the week.

HFO Watches/Warnings/Advisories

Flash Flood Watch through this afternoon for all Hawaii islands.
High Surf Advisory until 6 AM HST Thursday for Kauai Windward, Oahu Koolau, Olomana, Molokai Windward, Maui Windward West, Windward Haleakala, Big Island North and East.
Winter Storm Warning until 6 PM HST this evening for Big Island Summits.
Small Craft Advisory until 6 PM HST Wednesday for all Hawaiian waters.

Data Courtesy of NOAA.gov