Marine Weather and Tide Forecast for Kahaluu-Keauhou, HI

DISCUSSION
At 5 AM HST, Hurricane Lowell was about 145 miles northwest of Lihue or 245 miles northwest of Honolulu moving north at 18 mph as a category 1 (maximum sustained winds of 90 mph). IR satellite imagery shows mid and upper level clouds being sheared off the lower level circulation, typical of weakening tropical cyclone. As Lowell moves away from the Hawaiian Islands the next several days, further weakening is expected due to persistent shear and decreasing sea surface temperatures along its track.

Across Kauai, tropical storm force winds were widespread early this morning with several stations gusting to hurricane force. A handful of stations across northwest Oahu, mainly over and in the lee of the Waianae range, reported tropical storm force gusts.
Surface pressure gradients should loosen as the day progresses with southerly winds gradually easing.

Additional impacts from Lowell are expected to continue statewide, at least through this afternoon, and several headlines are in effect as a result. A High Surf Warning remains in effect for south facing shores for all islands, along with the west facing shores of the Big Island, though surf and swell should decline through the day. 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.

A Flood Watch remains in effect for the entire state through this afternoon as Lowell brings deep moist southerly flow across the islands. Mid to late week, both the GFS and ECMWF show the trailing band of deep moisture lingering over the eastern half of the state. Confidence is increasing that the Flood Watch will need to be extended for Big Island and possibly Maui County to cover any additional enhancement of shower activity. Diurnal heating, combined with a relatively deep moisture layer will also allow for a slight chance of thunderstorms over interior Big Island both this afternoon and Wednesday afternoon. See hydrology section for additional information.

The Tornado Watch has been cancelled for Kauai County and its surrounding waters. The center of Hurricane Lowell has now moved north of the state and the aforementioned area is no longer in the tornadic prone front right quadrant of the storm.

High pressure is forecast to build back in late Thursday through Saturday, bringing back a weak trade wind pattern. Moisture may still take a bit longer to exit the area, so expect some enhancement to shower activity to persist.



AVIATION
Hurricane Lowell continues its track northward, passing just west of Niihau and Kauai. 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 today.

Periods of MVFR conditions with low cloud ceilings and showers will linger across the state. MVFR shower activity will gradually decrease through the morning hours. Surface winds will also steadily decrease today.

AIRMET Sierra for low MVFR cloud ceilings remains in effect and will gradually diminish in coverage through the morning hours.

AIRMET Tango remains in effect for moderate low level turbulence affecting the island of Kauai and Oahu over and NW thru NE of island mountains. A strong surface wind AIRMET remains in effect for Kauai and Oahu for wind speeds greater than 30 knots due to Hurricane Lowell. These AIRMETs will likely be cancelled later this morning.



MARINE
Hurricane Lowell is now lifting north of Kauai and Niihau. 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 (SCA) also remains in effect for all remaining coastal waters for a combination of winds and seas. Winds and seas are expected to decrease rapidly today as the hurricane weakens and moves away from the islands, falling below SCA criteria by this evening. For the western offshore waters, hurricane conditions are expected to continue today until the cyclone exits the region to the northwest.

Southwest swell from Hurricane Lowell produced surf along south facing shores in excess of warning criteria overnight. This surf continues into the early morning hours, which may continue to bring damaging surf to portions of Kauai County with the potential for significant damage to coastal properties and infrastructure, particularly to those areas along the coast exposed to the southerly swell over the next several hours. Surf will quickly fall to advisory criteria and then below advisory criteria by tonight. An additional moderate, long-period south swell which is peaking today will then keep surf elevated just below advisory criteria once the southwest swell from Lowell fades by this afternoon. This southerly swell will maintain some south shore surf as it gradually fades through Thursday.

A medium-period east swell from former Tropical Storm Karina combined with east to southeast wind wave generated by Hurricane Lowell will maintain advisory level surf along east facing shores this morning, but will drop below advisory levels by tonight. Surf along north facing shores will experience a small bump on Tuesday with Lowell located northwest of the island chain and then fade through the week as it weakens and tracks away from the islands.



FIRE WEATHER
Fire weather risk will remain low the next several days due residual moisture associated with Hurricane Lowell. Expect a slight chance of thunderstorms over the Big Island on Wednesday afternoon and Thursday afternoon. Temperature inversion heights are expected to remain elevated or weak.



HYDROLOGY
Hurricane Lowell is expected to produce additional rainfall totals of 2 to 4 inches for Kauai, with maximum storm totals of 24 inches possible. For the Big Island, an additional 3 to 6 inches of rain is expected with isolated storm totals of 8 inches possible. For Oahu and Maui counties, an additional 1 to 3 inches of rain is expected with isolated storm totals of 8 inches possible. This rainfall may produce significant flash flooding and mudslides, especially across Kauai county and portions of the Big Island.



HFO WATCHES/WARNINGS/ADVISORIES
Flood Watch through this afternoon for all Hawaii islands-

High Surf Warning until 6 PM HST this evening 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 this evening 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 this evening 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.