Small Craft Advisory 33, NWS Honolulu, HI

Area Forecast Discussion
National Weather Service Honolulu HI
917 PM HST Tue Sep 11 2018

.SYNOPSIS...
Tropical Storm Olivia is forecast to move southwest across the
eastern part of the main Hawaiian Islands Wednesday morning.
As the system edges closer, expect the moisture to spread across
the entire area through Wednesday night. An upper level low
is forecast cut close to the islands, resulting in a very unstable
and unsettled period that will last into Saturday. A drier air mass
is expected to spread over the area the rest of the weekend.

&&

.DISCUSSION...
As of 730 pm HST, the deep convection of Olivia has separated,
leaving the low level circulation, below 10k feet exposed. It is
located on satellite about 100 miles east of Hana Maui. It is moving
southwest, toward Maui, at about 10 mph. The center of Olivia is
expect to cross Maui and the Alenuihaha Channel sometime Wednesday
morning, based on the 5 pm HST forecast. Trade wind showers have
picked up across windward areas of oahu, Maui, and the Big Island
in particular. During the rest of the night and into Wednesday
morning, continue to expect increasing showers and wind.

The heavier rain is likely to come Wednesday evening, as the
upper low is closer to the islands. The upper low is currently
about 600 miles northeast of Kauai, and is expected to move
southwest towards Kauai in the next 24 to 36 hours.

The threat of heavy rain continues even when Olivia is well
south of Oahu/Kauai Wednesday afternoon, even after the winds
from Olivia have subsided. The heaviest rain will likely shift to
Kauai on Thursday. A Flood Watch remains in effect for all islands
through Thursday night.

The atmosphere will gradually dry out and stabilize as the
moisture from Olivia and the low aloft move away to the west. This
is likely to occur over the upcoming weekend.

Please see the Hurricane Local Statement (HLSHFO) and Local
Watch/Warning Statement (TCVHFO) on our website for detailed
weather information about Olivia and expected impacts to your
local area. The Central Pacific Hurricane Center also posts the
latest Olivia Forecast Advisory tracks at weather.gov/cphc

&&

.AVIATION...
Tropical Storm Olivia continues to approach the state from the
east. Outer rain bands with showers continue to move onshore over
all islands. Expect numerous showers favoring mountain and
windward areas with scattered showers over leeward sections.
As Olivia approaches, wind speeds are forecast to gradually
strengthen tonight through Wednesday morning.

AIRMET SIERRA for mountain obscuration was expanded this evening
to include all island mountains and north through east sections.
AIRMET Tango remains in effect for strong winds producing moderate
low level turbulence over and south through west of mountains over
all islands.

SIGMET NOVEMBER is currently posted just east of the Hawaiian
Islands for Tropical Storm Olivia.

&&

.MARINE...
As Tropical Storm Olivia nears the islands from the east and
begins to directly affect the islands, winds will be on the
increase. For the latest on Olivia, please monitor the forecast
and advisory packages from the Central Pacific Hurricane Center.

Swell from Olivia has been spreading westward across the state.
Surf has been increasing and has already reached warning levels in
coastal sections of windward Big Island, and is expected to reach
warning levels along east facing shores from Maui to Oahu tonight
into Wednesday. A High Surf Warning (HSW) remains in effect for
east facing shores of the Big Island, Maui, Molokai, and Oahu
through Wednesday. Lower surf is expected for east facing shores
of Lanai and Kauai, so a High Surf Advisory (HSA) has been issued
for those areas through the same time period. Surf is expected to
decline fairly rapidly as Olivia exits the local waters.

A small northwest swell is expected late in the weekend and early
next week. No other significant swells are expected.

The morning coastal waters forecast will be delayed as we
incorporate the latest forecast information for Olivia.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Tropical Storm Warning for all Hawaii islands.

Flash Flood Watch through late Thursday night for all Hawaii
islands.

High Surf Warning until 6 PM HST Wednesday for Oahu South Shore-
Oahu Koolau-Olomana-Molokai-Maui Windward West-Maui Central
Valley-Windward Haleakala-South Big Island-Big Island North and
East.

High Surf Advisory until 6 PM HST Wednesday for Kauai Windward-
Lanai Makai.

Tropical Storm Warning for all Hawaiian waters.

&&

DISCUSSION...H Lau
Aviation...Bohlin
Marine...Kinel