West Side

Today: Breezy. Cloudy with frequent showers and isolated thunderstorms. Locally heavy rainfall possible. Highs 81 to 89. East winds up to 20 mph. Chance of rain 90 percent.

Tonight: Breezy. Frequent showers. Locally heavy rainfall possible. Lows 74 to 80. Southeast winds up to 20 mph. Chance of rain near 100 percent.

Tuesday: Breezy. Mostly cloudy with numerous showers. Highs 81 to 88. South winds 10 to 25 mph. Chance of rain 70 percent.

South Side

Today: Cloudy with frequent showers and isolated thunderstorms. Locally heavy rainfall possible. Highs around 89. North winds up to 15 mph. Chance of rain 90 percent.

Tonight: Breezy. Cloudy with frequent showers. Locally heavy rainfall possible. Lows 75 to 83. North winds up to 15 mph shifting to the south after midnight. Chance of rain 90 percent.

Tuesday: Windy. Mostly cloudy with numerous showers. Highs around 90. South winds up to 30 mph shifting to the southwest 10 to 30 mph in the afternoon. Chance of rain 70 percent.

North Shore

Today: Breezy. Frequent showers and isolated thunderstorms. Locally heavy rainfall possible. Highs around 82 near the shore to around 72 near 5000 feet. East winds 10 to 25 mph decreasing to up to 25 mph in the afternoon. Chance of rain near 100 percent.

Tonight: Breezy. Cloudy with frequent showers. Locally heavy rainfall possible. Lows around 76 near the shore to around 61 near 5000 feet. South winds up to 20 mph. Chance of rain 90 percent.

Tuesday: Mostly cloudy with numerous showers. Highs around 86 near the shore to around 73 near 5000 feet. Northwest winds up to 10 mph. Chance of rain 70 percent.

Central Maui

Today: Breezy. Cloudy with frequent showers and isolated thunderstorms. Locally heavy rainfall possible. Highs 82 to 89. East winds up to 25 mph. Chance of rain 90 percent.

Tonight: Cloudy and breezy. Frequent showers in the evening, then numerous showers after midnight. Locally heavy rainfall possible. Lows around 77. East winds up to 20 mph shifting to the southeast up to 10 mph after midnight. Chance of rain 80 percent.

Tuesday: Windy. Mostly cloudy with numerous showers. Highs 85 to 91. South winds up to 30 mph shifting to the southwest 10 to 30 mph in the afternoon. Chance of rain 70 percent.

Upcountry

Today: Breezy. Cloudy with frequent showers and isolated thunderstorms. Locally heavy rainfall possible. Highs around 73 at the visitor center to around 71 at the summit. Southeast winds up to 25 mph. Chance of rain 90 percent.

Tonight: Windy. Frequent showers. Locally heavy rainfall possible. Lows around 60 at the visitor center to around 51 at the summit. South winds up to 30 mph increasing to 10 to 30 mph after midnight. Chance of rain near 100 percent.

Tuesday: Breezy. Mostly cloudy with numerous showers. Highs 67 to 85. South winds up to 25 mph. Chance of rain 70 percent.

East Maui

Today: Breezy. Frequent showers and isolated thunderstorms. Locally heavy rainfall possible. Highs around 82 near the shore to around 72 near 5000 feet. East winds 10 to 25 mph decreasing to up to 25 mph in the afternoon. Chance of rain near 100 percent.

Tonight: Breezy. Cloudy with frequent showers. Locally heavy rainfall possible. Lows around 76 near the shore to around 61 near 5000 feet. South winds up to 20 mph. Chance of rain 90 percent.

Tuesday: Mostly cloudy with numerous showers. Highs around 86 near the shore to around 73 near 5000 feet. Northwest winds up to 10 mph. Chance of rain 70 percent.

Lanai City

Today: Cloudy with frequent showers and isolated thunderstorms. Locally heavy rainfall possible. Highs 79 to 86. East winds up to 15 mph. Chance of rain 90 percent.

Tonight: Breezy. Frequent showers. Locally heavy rainfall possible. Lows around 73. Southeast winds up to 15 mph increasing to 10 to 25 mph after midnight. Chance of rain near 100 percent.

Tuesday: Mostly cloudy. Breezy. Frequent showers in the morning, then numerous showers in the afternoon. Locally heavy rainfall possible in the morning. Highs 79 to 85. South winds 10 to 25 mph. Chance of rain 80 percent.

Kaunakakai

Today: Breezy. Frequent showers and isolated thunderstorms. Locally heavy rainfall possible. Highs 79 to 91. East winds 10 to 25 mph. Chance of rain near 100 percent.

Tonight: Breezy. Frequent showers. Locally heavy rainfall possible. Lows 66 to 79. Southeast winds 10 to 15 mph increasing to 10 to 25 mph after midnight. Chance of rain near 100 percent.

Tuesday: Mostly cloudy. Breezy. Frequent showers in the morning, then numerous showers in the afternoon. Locally heavy rainfall possible in the morning. Highs 79 to 92. South winds 10 to 25 mph decreasing to up to 25 mph in the afternoon. Chance of rain 80 percent.

Detailed Forecast

Synopsis

Trade winds will veer to the east-southeast and strengthen as Hurricane Lowell approaches. Lowell is forecast to pass west of of Kauai tonight, but close enough that a Hurricane Warning is in effect for Kauai and Niihau. High surf and heavy rain will impact all islands with strong winds mainly impacting the western end of the state.

Discussion

Hurricane Lowell is about 375 miles southwest of Kauai this morning moving north northeastward. Lowell's track has shifted eastward closer to Kauai and Niihau with advisory updates overnight, and the core of Lowell is expected to pass west of the Kauai. This has again has raised the possibility of hurricane force winds reaching Kauai and Niihau, as a result a Hurricane Warning has been issued for both islands. A Tropical Storm was has also been issued for Oahu also due to this eastward shift.
Additional impacts from Lowell are expected statewide, and a few headlines are in effect as a result. A High Surf Warning for south facing shores for the south swell generated by Lowell for all islands, along with the west facing shores of the Big Island. A High Surf Advisory remains in effect for the east swell generated by former Tropical Storm Karina, which has weakened to a post tropical low. For surf and other marine impacts, please see the marine section of the discussion below.
The Flood Watch for the state continues through Tuesday due to heavy rain brought in by Lowell and associated rain and thunderstorm bands. Terrain influence will play a big factor with isolated areas receiving significant amounts through the event. Stay alert for the issuance of any future flood advisories or warnings across the state. See hydrology section for additional information.
The threat of short-lived, fast-moving tornados/waterspouts will be present mainly near Kauai and Niihau as Lowell makes its closest approach to the islands. These would likely be embedded in rainbands. The threat for tornadoes is lower near the remaining islands, but not zero. The threat for tornadoes should decrease quickly early Tuesday morning.
Any deviation in track or intensity could also change how these hazards effect the islands.
High pressure is forecast to build back in Thursday through Saturday, bringing in a more typical trade wind pattern with a drier and more stable airmass.

Aviation

Hurricane Lowell continues its track northward, advecting unstable deep tropical moisture northward into the islands. Shower activity will continue to trend higher into Tuesday. MVFR conditions with low cloud ceilings and showers are expected statewide. Heavier showers will produce periods of IFR conditions. Surface winds will strengthen today over the western half of the state, as Hurricane Lowell continues on a northern track.
AIRMET Sierra for mountain obscuration continues for Kauai Oahu Molokai Maui and the Big Island. This AIRMET will likely continue into Tuesday.
AIRMET Tango was issued for moderate low level turbulence affecting the island of Kauai over and SW thru NW of island mountains. A strong surface wind AIRMET will likely be issued for Kauai and Niihau later today for wind speeds greater than 30 knots due to Hurricane Lowell approaching the islands.
Light icing continues in a layer between 160 and FL220 due to strengthening low level wind speeds as Lowell approaches the island.

Marine

Hurricane Lowell, located southwest of the islands, continues to move north-northeast this morning. As it approaches the island chain wind speeds will increase. A Hurricane Warning remains in effect for waters west of Kauai County, while a Tropical Storm Warning remains in effect for Kauai Channel and Kauai Windward Waters through Tuesday afternoon. A slight eastward shift in the track has also prompted the issuance of Tropical Storm Watches for Oahu Leeward and Windward Waters. The Small Craft Advisory remains in effect for all remaining coastal waters for a combination of winds and seas through Tuesday. Winds are expected to increasingly veer to the southeast to south as Lowell approaches and the strongest winds and highest seas are expected for the western end of the state.
Hurricane conditions are expected in the western offshore waters as Lowell through Tuesday as the center of the storm tracks just west of Niihau. Any slight deviation in the track to the west or east in the next 24 hours will have significant differences in impact for the coastal waters around Kauai County. Post-Tropical Cyclone Karina to the northeast of the islands will continue to weaken and dissipate later today.
South-southwest swell from Hurricane Lowell will rapidly build today. As a result, surf along south facing shores will begin to rise from advisory levels this morning to warning levels by this afternoon and peak overnight. The swell will increasingly shift out of the southwest tonight. Due to the track of Lowell west of the main islands, a sharp gradient in swell is expected from west to east. This will bring damaging surf to portions of Kauai County and possibly Oahu. Coinciding also with the peak monthly afternoon high tides, this could bring the potential for significant damage to coastal properties and infrastructure, including roadways to portions of Kauai and possibly Oahu. Swell energy is expected to rapidly decline on Tuesday.
A moderate, long-period south swell also arrives today and peaks overnight into Tuesday, but will be overwhelmed by the larger swell from Hurricane Lowell. Although it begins to fade on Tuesday, it will keep south shore surf somewhat elevated through Thursday. A large, medium-period east swell from former Tropical Storm Karina will combine with increasing east to southeast wind wave generated by Hurricane Lowell to keep advisory level surf along east facing shores through Tuesday. Surf along north facing shores will also experience a small increase on Tuesday as Lowell lifts north of the island chain and then fade through the week.

Fire weather

Fire weather risk will remain low through the forecast period due to increasing moisture moving over the islands in association with Hurricane Lowell. Thunderstorms will be possible through through tonight to the unstable airmass moving overhead. Temperature inversion heights are expected to remain elevated or non-existent during the next few days.

Hydrology

The potential for flooding exists through Tuesday, and as a result, a Flood Watch is in effect for the entire state. It is possible the watch may need to be extended into Tuesday night or Wednesday depending on the lingering rain bands across the state in the wake of Lowell as guidance suggests. However, will hold off any update to the watch at this time.
Hurricane Lowell is expected to bring additional rain to the islands through Wednesday morning with 6 to 10 inches, isolated 16 inches across Kauai. Oahu and Maui County, 4 to 8 inches, isolated 10 inches. Big Island, 4 to 8 inches, isolated 12 inches. This rainfall may produce significant flash flooding and mudslides, especially across Kauai County and south and east portions of the Big Island.

HFO Watches/Warnings/Advisories

Flood Watch through Tuesday afternoon for all Hawaii islands,
High Surf Warning until 6 PM HST Tuesday for Niihau, Kauai Leeward, Waianae Coast, Kahoolawe, Maui Leeward West, Kona, Kohala, Kauai South, East Honolulu, Honolulu Metro, Ewa Plain, Molokai Southeast, Molokai West, Molokai Leeward South, Lanai Leeward, Lanai South, Maui Central Valley South, Kipahulu, South Maui/Upcountry, South Haleakala, Big Island South, Big Island Southeast.
High Surf Advisory until 6 PM HST Tuesday for Olomana, Kauai East, Koolau Windward, Molokai Windward, Windward Haleakala, Big Island East, Big Island North.
Hurricane Warning for Niihau, Kauai,
Tropical Storm Watch for Oahu,
Hurricane Warning for Kauai Northwest Waters, Kauai Leeward Waters.
Tropical Storm Warning for Kauai Windward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters.
Small Craft Advisory until 6 PM HST Tuesday for Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Windward Waters, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov