Flash Flood Warning 10, NWS Honolulu, HI

Area Forecast Discussion
National Weather Service Honolulu HI
411 PM HST Fri Mar 13 2026

.SYNOPSIS...

A powerful kona storm will remain anchored northwest of the state
producing periods of hazardous weather impacts across the
Hawaiian Islands through the weekend. Expect a combination of
threats ranging from significant flash flooding, damaging winds,
strong to severe thunderstorms, and snow and ice over the highest
Big Island summits. Strong southerly to southwesterly will hold
through Saturday and producing damaging wind gusts. The highest
threats for damaging winds remain along north and east of the
island mountains. Unsettled wet weather conditions with decreasing
southwesterly wind trends will continue into early next week.
This kona storm begins to lift northward on Monday, and unsettled
weather will start to ease across the Hawaii region. High pressure
will build back in north of the state during the second half of
next week allowing trade winds to gradually return from north to
south.

&&

.DISCUSSION...

A powerful kona storm continues to strengthen roughly 800 sm
northwest of the state. A broad band of showers with embedded
thunderstorms is currently draped across the central island chain
with Kauai along the western edge of this cloud band. Moderate to
locally heavy showers have been persistent across the state with
12 hour rainfall total reaching 5 to 8 inches for some of the
wetter locations from Kauai to Maui County. Southerly winds have
strengthen to warning levels today with peak gusts up in excess of
60 mph for these islands. Strong winds in excess of 70 mph have
been observed at the summits Haleakala and the Big Island thus a
High Wind Warning remains in effect across the state. A Winter
Storm Warning also remains in effect for Big Island Summits.

Forecast remains on track showing the kona low deepening to our
northwest allowing for the threat of thunderstorms and severe
winds and the potential for severe thunderstorms to continue
through tonight as this event peaks into Saturday. The main band
of moderate to heavy showers will shift eastward tonight and
Saturday before becoming nearly stationary over Maui County and
the Big Island. Thus a Flood Watch remains in effect for these
areas through Sunday night. Bands of showers and thunderstorms
are still forecast to impact Kauai and Oahu into Saturday but the
overall trend will be coming down for Kauai early Saturday morning
and for Oahu Saturday afternoon. The Flash Flooding threats will
continue for Kauai through Saturday afternoon and Oahu through
Saturday night due to both saturated soil conditions that more
easily lead to ground runoff and flooding from even more moderate
continuous rainfall rates. The highest flood threats across the
state will favor southern and western slopes.  These are typically
the drier sides of the islands, less accustomed to heavy rain and
flooding. Driving under these heavy shower bands will become
challenging with ponding of water on area roadways. Current weather
trends in this pattern will change rapidly, these threats to life
and property will develop swiftly and can affect any location in
the Hawaiian Islands. Postpone outdoor activities or travel if
possible until early next week as the kona storm begins to drift
northward away from the islands and the threat level across the
state diminishes.

From Saturday night to Sunday an upper level short wave trough
will shift over the state leading to another upward pulse in
moderate to heavy shower activity, particularly over Maui County
and the Big Island where the main rainband will remain nearly
stationary. The threat of thunderstorms will also continue.

Monday and Tuesday, the large kona storm begins to weaken and lift
northward, slowly drifting away from the Hawaiian Islands. This
means wet weather will continue over and near Maui County and the
Big Island but should see improvement elsewhere.

The extended forecast shows various outcomes during the second
half of next week. GFS shows a high pressure system building back
into position just north of the island chain as earlier as
Wednesday while other deterministic and ensemble models show the
high building in Thursday with trades bringing more typical brief
passing showers over windward mountain areas. Will continue to
monitor latest trends.

&&

.AVIATION...

Widespread showers, some heavy, along with isolated thunderstorms,
will continue into Saturday. Expect widespread MVFR to IFR with
local LIFR. Winds will remain primarily out of the south and
increase through the day. Widespread gusts up to and over 35 kt
are forecast. There may be a brief break in the rain this evening
and overnight, especially for Kauai and Oahu, before showers are
expected to become widespread once again during the day Saturday.

AIRMET Sierra remains in effect all islands due to mountain
obscuration. This is expected to remain in effect through
tonight.

AIRMET Tango remains in effect for moderate upper-level turbulence
between FL240 and FL360. and for low-level turbulence due to
strong surface winds. Both of these are expected to remain in
effect through tomorrow.

AIRMET Zulu remains in effect, as high clouds from these showers
present icing concerns between FL120 and FL260. This is also
expected to continue through tomorrow.

&&

.MARINE...
ASCAT passes this morning showed gale-force winds in the waters
near Oahu and Maui County this morning, and radar signatures
supported gale-force winds with some of the strongest bands of
showers moving through the area in association with the strong
kona storm impacting the area. Gusty winds, steep and fast
building seas, and low visibility in heavy showers will continue
across the entire marine waters through the weekend.

The Gale Warning near Kauai and Oahu was expanded to include Maui
County following the morning ASCAT pass. The Gale Warning was
expanded to include waters near the Big Island starting tonight.
The winds are expected to weaken near Kauai and Oahu tomorrow, but
continue near Maui County and the Big Island through tomorrow
night. The winds by early next week will shift westerly and
diminish as the storm gains increasing distance far to the north
of the islands.

A small, short to medium period west to west-northwest swell will
bring small to moderate surf to north and west facing shores
through the weekend. Kauai will block some of this swell energy
from reaching Oahu and Maui, but it will make it into the west
facing shores of the Big Island. Additionally, a small, medium
period north swell will peak Saturday before gradually declining.

Rough and choppy surf will continue along south-facing shores due
to the south to southeast wind direction, and with the increased
winds, is expected to peak just below advisory levels. Once
southerly winds diminish early next week, a small to moderate,
long-period south swell generated by a gale force low east-
southeast of New Zealand will arrive along south-facing shores
and build into midweek. Surf along east-facing shores will remain
below seasonal levels as south to southeast winds prevail.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until 6 AM HST Sunday for Niihau-Kauai Leeward-
Kauai Mountains-Waianae Coast-Oahu North Shore-Olomana-Central
Oahu-Waianae Mountains-Lanai Mauka-Kahoolawe-Maui Windward West-
Maui Leeward West-Kona-Kohala-Big Island Interior-Kauai North-
Kauai East-Kauai South-East Honolulu-Honolulu Metro-Ewa Plain-
Koolau Windward-Koolau Leeward-Molokai-Lanai Windward-Lanai
Leeward-Lanai South-Maui Central Valley North-Maui Central
Valley South-Windward Haleakala-Kipahulu-South Maui/Upcountry-
South Haleakala-Big Island South-Big Island Southeast-Big Island
East-Big Island North.

Flood Watch through Saturday afternoon for Niihau-Kauai-

Flood Watch through late Saturday night for Oahu-

Flood Watch through late Sunday night for Lanai Mauka-Kahoolawe-
Maui Windward West-Maui Leeward West-Haleakala Summit-Kona-
Kohala-Big Island Interior-Molokai-Lanai Windward-Lanai Leeward-
Lanai South-Maui Central Valley North-Maui Central Valley South-
Windward Haleakala-Kipahulu-South Maui/Upcountry-South Haleakala-
Big Island South-Big Island Southeast-Big Island East-Big Island
North.

High Wind Warning until 6 PM HST Sunday for Haleakala Summit-Big
Island Summits.

Winter Storm Warning until 6 PM HST Saturday for Big Island
Summits.

Gale Warning until 6 AM HST Saturday for Kauai Northwest Waters-
Kauai Windward Waters-Kauai Leeward Waters-Kauai Channel-Oahu
Leeward Waters.

Gale Warning until 6 AM HST Sunday for Oahu Windward Waters-
Kaiwi Channel-Maui County Windward Waters-Maui County Leeward
Waters-Maalaea Bay-Pailolo Channel.

Gale Warning until 6 AM HST Sunday for Alenuihaha Channel-Big
Island Windward Waters-Big Island Leeward Waters-Big Island
Southeast Waters.

&&

DISCUSSION...Almanza
AVIATION...Evans
MARINE...M Ballard

Preliminary Local Storm Report
National Weather Service Honolulu HI
310 PM HST Fri Mar 13 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0100 PM     Non-Tstm Wnd Gst 3 SSE Puuanahulu        19.77N 155.83W
03/13/2026  M68 MPH          Hawaii             HI   Public

            Kaiaulu Puuwaawaa.

&&

JVC

Preliminary Local Storm Report
National Weather Service Honolulu HI
316 PM HST Fri Mar 13 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0126 PM     Non-Tstm Wnd Gst 4 NE Kula               20.80N 156.29W
03/13/2026  M69 MPH          Maui               HI   Mesonet

            Waihou Springs 1.

&&

JVC

Preliminary Local Storm Report
National Weather Service Honolulu HI
326 PM HST Fri Mar 13 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0317 PM     Flash Flood      1 NNW Kihei             20.78N 156.46W
03/13/2026                   Maui               HI   Emergency Mngr

            A section of South Kihei Road is closed in
            both directions, between North Kihei Road
            and Uwapo Road due flooding.

&&

Preliminary Local Storm Report
National Weather Service Honolulu HI
359 PM HST Fri Mar 13 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0326 PM     Non-Tstm Wnd Gst 3 WNW Kula              20.78N 156.37W
03/13/2026  M64 MPH          Maui               HI   Public

            Kaonolulu 1.

&&

JVC

Preliminary Local Storm Report
National Weather Service Honolulu HI
401 PM HST Fri Mar 13 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0348 PM     Non-Tstm Wnd Gst 4 ESE Kula              20.74N 156.27W
03/13/2026  E59 MPH          Maui               HI   Public

            Kamehamenui 1.

&&

JVC

Preliminary Local Storm Report
National Weather Service Honolulu HI
508 PM HST Fri Mar 13 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0500 PM     Flash Flood      6 ESE Kaunakakai        21.06N 156.93W
03/13/2026                   Maui               HI   Emergency Mngr

            Kamehameha V Highway, between mile post
            marker 6 and mile post marker 8.5.

&&