510
FXHW60 PHFO 061930
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
930 AM HST Sun Sep 6 2026

.SYNOPSIS...
Breezy east-northeast trade winds will gradually veer to the east
and then east-southeast over the next couple of days as Hurricane
Lowell approaches the western islands from the southwest. Lowell
is forecast to pass west of Kauai`s coastal waters Monday night. A
Tropical Storm Warning is in effect for Kauai, Niihau and the
surrounding coastal waters as a result. Impacts such as high surf
and heavy rain could impact all of the islands.

&&

.DISCUSSION...
Hurricane Lowell is about 550 miles south-southwest of Kauai this
morning. Lowell is expected to move northward, and pass west of
the Kauai coastal waters late Monday through Monday night.
Tropical Storm force winds are expected to reach Kauai and Niihau
at the the closet approach, and thus a Tropical Storm Warning is
in effect for Kauai County and the surrounding coastal waters.
Additional impacts from Lowell are expected statewide, and a few
headlines are in effect as a result. A High Surf Advisory is in
effect for south and east facing shores. The south swell is from
Lowell, and the east swells are from Tropical Storm Karina, which
is about 1000 miles east of Kauai this morning. Karina is expected
to dissipate within the next 48 hours when its a few hundred miles
east-northeast of Kauai.

Showers have already been focused over the windward sides of the
islands in the trade wind flow. As the winds shift to the
southeast tonight, showers will spread to additional areas of the
islands. The interaction of the terrain with moisture spreading
over the islands could lead to heavy rainfall which could cause
some flooding. Thus a Flood Watch is in effect for all islands
starting at noon today, and persisting through Tuesday afternoon.
With Kauai and Niihau being the closest to Lowell, rainfall
totals are expected to be highest there, but due to the terrain
influence on the Big Island, isolated areas could receive
significant rain. Due to an unstable airmass moving over the
islands, thunderstorms are possible starting tonight and
persisting statewide through tomorrow. These thunderstorms could
produce heavy rainfall which could also lead to some flooding. Stay
alert for the issuance of any flood advisories or warnings.

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.

For surf and other marine impacts, please see the marine section
of the discussion below.

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...

Tropical moisture will deepen over the next 24 hours as wind
directions aloft shift from a more southerly direction in
response to Hurricane Lowell`s northward track passing just west
of Kauai. This unstable tropical air mass will produce increasing
clouds and showers across the state with the highest chances for
MVFR conditions in low cloud ceilings and showers expected from
later this afternoon into Tuesday.

Surface winds will continue to blow from a more easterly
direction for most areas with stronger wind gusts near heavy rain
shower bands and thunderstorms forecast through Monday night.
Winds are expected to begin strengthening and start veering to an
ESE direction overnight, especially over the western half of the
state.

Tropical Storm force winds are possible near Niihau and Kauai from
Monday into Tuesday. MVFR/IFR conditions and wind impacts for
Kauai County will depend on subtle deviations in the northward
track of Hurricane Lowell. Please closely monitor weather
conditions for this time period as weather impacts are likely to
evolve over time as Lowell continues its northward journey.

AIRMET Sierra for mountain obscuration continues for Kauai Oahu
Molokai Maui and the Big Island for the foreseeable future. This
AIRMET will likely be expanded to cover other areas and islands
as shower coverage increases with time. AIRMET Tango may be
necessary for moderate turbulence downwind of terrain once winds
start to ramp up with Hurricane Lowell`s approach.


&&

.MARINE...

A surface high north of the Hawaiian Islands will persist through
the forecast period. Meanwhile, Hurricane Lowell is around 500 nm
south- southwest of Kauai, now tracking north-northwest. Lowell
will continue to turn north today and as it approaches the island
chain winds will begin to increase. Therefore, a Small Craft
Advisory (SCA) is now in effect for the windier waters and
channels around Maui County and the Big Island. Winds will
increasingly veer to the southeast to south as Lowell continues to
approach, bringing the strongest winds to the western end of the
state. Winds and seas will likely exceed small craft criteria
across all coastal waters on Monday, which will necessitate an
expansion of the SCA. Where winds are expected to be strongest
around Kauai County, a Tropical Storm Warning is in effect.

Hurricane conditions are expected in the offshore waters west of
159W Sunday night through Tuesday as the center of the hurricane
tracks west of Niihau. While confidence is increasing in the
track forecast of the cyclone, any slight deviation in the track
to the west or east from the current predicted path will have
significant differences in impact for the coastal waters around
Kauai County. As for Tropical Storm Karina, it is expected to
weaken and dissipate as it moves northeast of the state. by
Monday.

Southerly swell generated by Hurricane Lowell will keep surf along
south facing shores at High Surf Advisory criteria through at
least Monday night. As Lowell begins to turn more north, its swell
will gradually veer from south to southwest and begin a rapid upward
trend by Monday. Very large surf exceeding warning criteria is likely
for south and west facing shores of Oahu and Kauai, and surf may also
reach warning levels for the west facing shores of the Big Island,
including the Kohala coast on Monday. Coinciding also with
monthly high tides, this will create the potential for impacts to
harbor entrances, channels, as well as vulnerable coastal
properties and infrastructure including roadways. Surf will then
rapidly decrease on Tuesday after the hurricane passes north of
the island chain. A pulse of northwesterly swell could then bring
a minor bump to north shore surf on Tuesday and fade through
Thursday.

East facing shores will see continued advisory level surf from a
large, medium-period east swell generated by Tropical Storm Karina to
the east of the islands. This swell will gradually fade early this
week as Karina weakens. Late next week, surf along east facing shores
could be bolstered by some medium-period swell generated by Hurricane
Marie in the East Pacific. Otherwise, expect choppy conditions from
easterly trade wind swell 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 tonight and
tomorrow due to the unstable airmass moving overhead. Temperature
inversion heights are currently near 11,000 ft from Maui to the
Big Island, and are expected to remain elevated during the next
few days.

&&

.HYDROLOGY...
Heavy rain is possible tonight through Tuesday afternoon, and as a
result, a Flood Watch is in effect for the entire state. Hurricane
Lowell is expected to produce rainfall totals of 6 to 10 inches
for Kauai, with maximum totals of 14 inches possible. For the Big
Island, 4 to 8 inches of rain is expected with isolated totals of
12 inches possible, due to the terrain influence with the
southeast flow. Across the remaining islands, rainfall of 2 to 4
inches of rain is expected, with Maui having isolated maximum
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...
High Surf Advisory until 6 AM HST Tuesday for Big Island East-
Big Island North-Big Island South-Big Island Southeast-East
Honolulu-Ewa Plain-Honolulu Metro-Kahoolawe-Kauai East-Kauai
South-Kauai Southwest-Kipahulu-Kona-Koolau Windward-Lanai
Leeward-Lanai South-Maui Central Valley South-Maui Leeward West-
Molokai Leeward South-Molokai Southeast-Molokai West-Molokai
Windward-Niihau-Olomana-South Haleakala-South Maui/Upcountry-
Waianae Coast-Windward Haleakala.

Tropical Storm Warning for Kauai East-Kauai Mountains-Kauai
North-Kauai South-Kauai Southwest-Niihau.

Flood Watch through Tuesday afternoon for Big Island East-Big
Island Interior-Big Island North-Big Island South-Big Island
Southeast-Big Island Summits-Central Oahu-East Honolulu-Ewa
Plain-Haleakala Summit-Honolulu Metro-Kahoolawe-Kauai East-Kauai
Mountains-Kauai North-Kauai South-Kauai Southwest-Kipahulu-
Kohala-Kona-Koolau Leeward-Koolau Windward-Lanai Leeward-Lanai
Mauka-Lanai South-Lanai Windward-Maui Central Valley North-Maui
Central Valley South-Maui Leeward West-Maui Windward West-
Molokai Leeward South-Molokai North-Molokai Southeast-Molokai
West-Molokai Windward-Niihau-Oahu North Shore-Olomana-South
Haleakala-South Maui/Upcountry-Waianae Coast-Waianae Mountains-
Windward Haleakala.

Tropical Storm Warning for Kauai Channel-Kauai Leeward Waters-
Kauai Northwest Waters-Kauai Windward Waters.

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


&&

$$

DISCUSSION/FIRE WEATHER/HYDROLOGY...M Ballard
AVIATION...DT
MARINE...Shigesato