textproduct: Honolulu

SYNOPSIS

Southeast to south winds will remain strong tonight as Hurricane Lowell makes its closest approach to Ni'ihau and Kauai. The core of Lowell continue moving northward by Tuesday morning, away from the islands. Damaging hurricane conditions are will continue on Kauai with numerous threats in place throughout the state. A Hurricane Warning is in effect for Kauai and Niihau and a Tropical Storm Warning is in effect for Oahu. High surf and heavy rain will impact all islands with strong winds mainly impacting the western end of the state. Winds will ease later in the day on Tuesday.

DISCUSSION

At 11 PM HST, Hurricane Lowell was about 90 miles west of Lihue or 190 miles west northwest of Honolulu moving north northeastward at 18 mph as a high end category 2 (maximum sustained winds of 110 mph). IR satellite imagery shows an obscured eye as a mid and upper level cloud shield dominates over the center. Tropical Storm force winds are widespread across Kauai. Several stations on the leeward side of the island, between Waimea and Barking Sands, have already gusted to above hurricane force. On Oahu, winds continue to increase as well with many stations, mainly concentrated over the Waianae mountain range and downslope of its terrain, reporting gusts to tropical storm force. The core of Lowell is will make its closest approach to Ni'ihau and Kauai in the next couple of hours, before departing northward and away from the state.

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 through early Tuesday morning. A tornado watch is in effect for Kauai and Niihau. Any tornadoes 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.

High pressure is forecast to build back in Thursday through Saturday, bringing in a more typical trade wind pattern. Moisture may take a bit longer to exit the area as well, so conditions are expected to dry out more gradually into the weekend.

AVIATION

Hurricane Lowell continues its track northward, passing just west of Niihau and Kauai this evening. Deep unstable tropical moisture continues to stream northward across all islands. Shower activity will linger even after Lowell begins to move farther northward away from the Hawaiian Islands.

Periods of MVFR conditions with low cloud ceilings and showers will linger across the state into Tuesday. Heavier showers will produce brief periods of IFR conditions. Shower activity will gradually decrease through Tuesday. Surface winds will also steadily decrease through the morning hours as Lowell moves northward.

AIRMET Sierra for IFR conditions continue for Kauai and Oahu. Elsewhere mountain obscurations remain in effect for Molokai Maui and the Big Island. Low MVFR cloud ceilings will gradually diminish in coverage through the Tuesday morning hours.

AIRMET Tango remains in effect for moderate low level turbulence affecting the island of Kauai and Oahu over and SW thru NW of island mountains. A strong surface wind AIRMET was issued for Kauai and Oahu for wind speeds greater than 30 knots due to Hurricane Lowell approaching the islands. These AIRMETs will likely be cancelled by late Tuesday morning.

Light icing continues in a layer between 160 and FL220.

MARINE

Hurricane Lowell is on track to pass west of Niihau over the coming hours. Winds and seas are on the increase as the system approaches, and both are expected to peak overnight as Lowell makes it closest approach to Kauai County. A Hurricane Warning remains in effect for waters west of Kauai County, while a Tropical Storm Warning remains in effect for Kauai Channel, Kauai Windward Waters, Oahu Windward Waters and Oahu Leeward 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 and eventually south tonight as Lowell approaches and begins to lift north of the island chain by Tuesday morning. The strongest winds and highest seas are expected for the western end of the state.

Hurricane conditions are expected in the western offshore waters through Tuesday as the center of Lowell tracks just west of Niihau. What remains of former Tropical Cyclone Karina remains to the northeast of the islands and is expected to dissipate soon.

South-southwest swell from Hurricane Lowell will continue to build rapidly and peak tonight as it shifts out of the southwest. As a result, warning level surf along south facing shores will continue to rise, peaking overnight. 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 likely Oahu, with the potential for significant damage to coastal properties and infrastructure, particularly to those areas along the coasts of Kauai and Oahu exposed to the southerly swell. The hurricane swell energy is expected to rapidly decline on Tuesday as Lowell moves away from the islands.

A moderate, long-period south swell will peak overnight and into Tuesday, but will be overwhelmed by the larger swell mentioned above from Hurricane Lowell. This swell will also fade some on Tuesday but 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

Over the past 48 hours, generally 3 to 10 inches of rain has fallen on Kauai with slightly over 17 inches reported at the Mount Waialeale rain gauge. Generally 1 to 3 inches of rain has fallen over Oahu with 5 to 9 inches accumulating over the Koolau range. 5 to 10 inches of rain have fallen along the winds slopes of Maui with much less reported in the lower elevations of Maui, Lanai, and Molokai. 3 to 5 inches of rain has fallen along windward and southeastern facing Big Island with less than an inches for leeward sides. The potential for flooding remains through late Tuesday, and a Flood Watch remains in effect for the entire state. Due to the amount of rain that has fallen, especially over Kauai today, any heavy showers could trigger quick flash flooding. The watch may need to be extended through midweek as lingering moisture will remain in place in the wake of Lowell.

Hurricane Lowell is expected to bring additional rain to the islands through Wednesday afternoon with 3 to 5 inches across Kauai. Oahu and Maui County, 1 to 3 inches. Big Island, 3 to 5 inches. This rainfall may produce significant flash flooding and mudslides, especially across Kauai County, Oahu, and potentially east portions of the Big Island. Its important to note that any pop up thunderstorms that develop could dramatically increase total rainfall amounts anywhere.

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.

Hurricane Warning for Niihau-Kauai-

Tropical Storm Warning for Oahu-

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 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.