Wildfire in Hawaii, August 24 to 25, 2018

Area Forecast Discussion
National Weather Service Honolulu HI
523 AM HST Fri Aug 24 2018

.SYNOPSIS...
Hurricane Lane is forecast to continue inching northward into the
area today, then gradually make a turn toward the west late tonight
through Saturday, while passing near or just south of Oahu and
Kauai. The potential for flash flooding along with increasing
winds are expected through this time. Provided Lane's slow forward
speed, this will be a long-duration event with the potential for
heavy rain continuing through the weekend and into early next
week, even as Lane begins to track westward and away from the
state. Additionally, coastal impacts associated with large surf
and rising water levels will lead to inundation and overwash onto
vulnerable low-level coastal areas through Saturday.

&&

.DISCUSSION...
The 5 am HST advisory from the Central Pacific Hurricane Center
(CPHC) has Hurricane Lane slowly moving northward toward the main
Hawaiian Islands at 5 mph, located about 180 miles south of
Honolulu (145 miles WSW of Kailua-Kona). Maximum sustained winds
associated with Lane are 110 mph, which is a category 2 on the
Saffir-Simpson Hurricane Wind Scale. Lane is forecast to continue
on this track today as it moves near the islands. Lane is then
forecast to gradually make a turn toward the west late tonight
through Saturday and pass south of Oahu and Kauai.

Do not to focus on the exact track of Lane as impacts are
expected far away from its center. Catastrophic flooding has
already occurred on the Big Island over the past 36 hours where
peak rainfall totals have reached the 30 inch mark. This threat
along with damaging winds is expected to expand westward over the
smaller islands today through Saturday as Lane moves into the
area. Out at the beaches and along low-lying coastal areas, life-
threatening surf combined with storm surge will translate to
inundation and/or overwash potentially making roads impassable.
The greatest potential for these coastal threats will occur along
south and southeast facing shores.

For the extended period (next week), deep tropical moisture axis
trailing Lane is forecast to hold over the western end of the state
through the first half of the week as Lane turns northward well west
of Kauai. This will keep the threat for heavy rainfall and flooding
in place, mainly for Kauai and Oahu. Confidence remains low through
the second half of the week due to large model differences. The
ECMWF depicts another tropical cyclone developing and moving into
the central Pacific while the GFS only shows a weak and broad trough
or low.

For additional details with regard to impacts for each island
associated with Lane, refer to the latest local statements issued
with each advisory package (next issuance 11 pm - midnight;
TCV/HLS).

&&

.AVIATION...
Current radar imagery indicates the heaviest rainfall to be
occurring across northeast Big Island and the waters just east of
Maui. Expect Isolated IFR ceilings and visibilities in these
locally heavy downpours. Conditions are forecast to spread
gradually north and west over the next 12 to 24 hours.

AIRMET Sierra for mountain obscuration is in effect for north
through east sections of the Big Island, Maui, Molokai, and Oahu.
Conditions will continue to expand and will likely include all
principal islands by midday Friday.

Isolated thunderstorm activity is possible across the whole of the
forecast area, but is most likely to occur over Leeward Big
Island and Maui County this morning then Maui County and Oahu in
the afternoon.

The sharp contrast of strong high pressure to the north and
falling pressures to the south will maintain strong straight-line
winds across most of the state. An Airmet is currently in effect
for mechanical low level turbulence to the leeward side of all
mountains.

AIRMET Tango is also in effect for waters within 40nm S of the
Big Island as well as the Pailolo and Alenuihaha Channels in
response to the strong cyclonic surface winds associated with
Hurricane Lane. Conditions are expected to gradually intensify and
expand northwestward over the next 24 hours.

Light rime icing is expected in layered clouds above FL200.

&&

.MARINE...
Hurricane Lane is currently slowly tracking north and is forecast
to move very close or over the leeward waters of the smaller
islands today through Saturday. Latest radar imagery is showing
heavy bands of rain moving into the coastal waters surrounding
Maui County and Oahu Leeward waters. Heavy rain will continue to
increase through the day today as Lane approaches the coastal
waters.

Surf will rapidly increase this afternoon along south facing
shores as Hurricane Lane approaches the Hawaiian Islands. Surf may
reach historic levels this evening and tonight, thus a High Surf
Warning is in effect across south facing shores of the smaller
islands. Also, latest observations from Honolulu Harbor is
showing water levels running about 0.5 ft above the predicted tide
levels. Increasing surf will further increase water levels and
significant overwash along low-lying coastal areas and road ways
will be possible, especially during the high tide this afternoon.
Increasing northeast to east winds will also bring large
disorganized breakers to east facing shores through Saturday.

See the Coastal Hazard Message (HFOCFWHFO) for surf advisories
and warnings and the Marine Weather Message (HFOMWWHFO) for
marine warnings over the coastal waters. The Ocean Prediction
Center will be preparing the Offshore Waters Forecast for Hawaii.

See the latest Collaborative Surf Discussion (SRDHFO) for more
details on surf and swell from other sources.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Hurricane Warning for Oahu-Molokai-Lanai-Kahoolawe-Maui.

Flash Flood Watch through late tonight for all Hawaii islands.

High Surf Warning until 6 AM HST Saturday for Niihau-Kauai
Windward-Kauai Leeward-Oahu South Shore-Waianae Coast-Molokai
Leeward-Lanai Makai-Kahoolawe-Maui Leeward West-Maui Central
Valley-Leeward Haleakala-Kona.

Hurricane Watch for Niihau-Kauai.

Tropical Storm Warning for Big Island.

High Surf Advisory until 6 PM HST Saturday for Oahu Koolau-
Olomana-Molokai Windward-Maui Windward West-Windward Haleakala-
South Big Island-Big Island North and East.

Hurricane Warning for Kauai Channel-Oahu Leeward Waters-Kaiwi
Channel-Maui County Leeward Waters-Maalaea Bay-Pailolo Channel-
Alenuihaha Channel-Big Island Leeward Waters-Big Island
Southeast Waters.

Hurricane Watch for Kauai Northwest Waters-Kauai Windward Waters-
Kauai Leeward Waters.

Tropical Storm Warning for Oahu Windward Waters-Maui County
Windward Waters-Big Island Windward and Kauai leeward Waters.

&&

DISCUSSION...Gibbs
AVIATION...Bedal
MARINE...Kino