Winter Storm Warning 3, NWS Honolulu, HI

Area Forecast Discussion...CORRECTED
National Weather Service Honolulu HI
920 AM HST Thu Mar 12 2026

.SYNOPSIS...

A powerful kona storm will produce 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. Southwesterly winds will be
strongest from Friday to Saturday and will produce damaging wind
gusts along north and east of the island mountains. Unsettled wet
weather conditions with southwesterly winds will continue into
early next week. The 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
allowing trade winds to return from next Wednesday onward.

&&

.SHORT TERM UPDATE...
Issued at 904 AM HST Thu Mar 12 2026

Latest satellite imagery shows a complex surface low over the
Central Pacific basin with bands of widely scattered moderate
thunderstorms along the eastern flank of low. One of these bands
of thunderstorms is currently moving over Oahu and Maui County
with 1 to 3 inches of rainfall falling in the past 6 hours across
these islands. Latest high resolution model guidance shows this
band moving off to the northeast and another band moving over the
state from the south later this morning and afternoon, bringing
another round of widely scattered thunderstorms with moderate to
locally heavy showers.

&&

.PREV DISCUSSION...
Moderate to heavy showers continued to pulse through the islands
last night through the early morning hours. Brief thunderstorms
were observed over portions of northern Oahu and over marine
coastal areas through the night. The latest morning satellite
water vapor imagery continues to show a complex and large upper
low set up across the Central Pacific basin. Smaller short wave
troughs are rotating counterclockwise around this larger central
low.

A brief respite in the flooding and thunderstorm threats last
night will change later today as another weak, negatively tilted,
short wave trough moves over the islands from the late morning
through the afternoon hours. The negative tilt on this upper
trough will produce more efficient atmospheric lifting dynamics,
leading to heavier showers and higher potential for strong
thunderstorm activity. Increasing trends in moderate to heavy
showers and thunderstorms will continue into the overnight hours
as a stronger negatively tilted short wave trough moves into the
islands.

The threat for Flash Flooding will continue into the weekend 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 of all islands. 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. A Flood Watch
continues for all Hawaiian Islands into Saturday, this Flood
Watch may need to be extended in time as the heavy rainfall threat
may linger into Sunday.

By Friday, the weather conditions become vastly more severe, as
stronger southwesterly winds providing damaging wind gusts along
island mountain slopes, favoring northern and eastern slopes of
steep mountain terrain. Already saturated ground conditions and
trees unaccustomed to southwest winds will fall and likely cause
blocked roadways and lead to power outages. These strong southwesterly
winds will continue through Saturday afternoon. These stronger
southwest winds speed up into the 50 to 70 MPH range around the
5,000 foot level. These winds will also converge at the lower
levels, lifting the atmosphere and producing strong convective
heavy shower and thunderstorm bands. As these clouds reach higher
and higher heights in the atmosphere they will reach up and pull
down these stronger winds to the surface, yielding wind gusts in
the 50 to 70 mph range in the strongest thunderstorm cells. This
means even outside of terrain enhancing wind gusts any strong
thunderstorms are capable of producing severe hurricane force wind
gusts over islands or coastal waters through Saturday. A High
Wind Watch remains in effect to cover these damaging wind threats.

Some of these stronger thunderstorms will likely become severe
with the heaviest rainfall rates and strong damaging winds. High
levels of instability, wind shear and atmospheric forcing
ingredients are all coming into focus over the islands from
Friday through Saturday for a potential severe weather event. A
Severe Thunderstorm Watch may be needed during the Friday through
Saturday time period. However, we will likely wait until we see
these severe thunderstorm developing over the local area before
pulling the trigger on this Severe Thunderstorm Watch with a short
lead time measured in hours.

From Saturday night to Sunday another upper level short wave
trough passes over the islands leading to another upward pulse in
moderate to heavy shower activity. Thunderstorms will also
threaten the islands and become more of a flooding threat as
decreasing upper level and surface wind speeds diminish the
damaging wind gust threats.

Monday and Tuesday, the large kona storm begins to lift northward
drifting slowly away from the Hawaiian Islands. This means wet
weather continues, however moderate to heavy rainfall rates will
decrease and southwest winds will gradually weaken through the
first half of next week.

By Wednesday, the latest long range guidance shows a high pressure
system building back into position just north of the island chain,
allowing a return to a typical trade wind weather pattern with
more typical brief passing showers over windward mountain areas.

&&

.AVIATION...
Issued at 904 AM HST Thu Mar 12 2026

A band of showers with embedded thunderstorms will move across the
islands east of Kauai this morning, before shower activity becomes
more scattered this afternoon. Expect MVFR to IFR conditions under
showers, to locally as low as LIFR. Winds will remain primarily
out of the south and southeast. Showers are then expected to
become more widespread this evening, starting at Kauai and moving
eastward.

AIRMET Sierra remains in effect for Kauai, Oahu, Molokai, Lanai,
and Maui due to mountain obscuration from showers. Some relief is
expected this afternoon as showers decrease in coverage, but
current thinking is that this AIRMET will remain in effect so long
as shower activity persists across the islands.

AIRMET Tango remains in effect for moderate upper-level turbulence
between FL240 and 360. This ongoing Kona low should keep
turbulence prevailing over the next few days.

AIRMET Zulu is also in effect, as high clouds from these showers
present icing concerns between FL130 and 260. Once again, some
relief is expected this afternoon, before high clouds envelop the
islands once again later this evening.

&&

.MARINE...
Issued at 402 AM HST Thu Mar 12 2026

A powerful kona storm will continue to bring heavy rain,
thunderstorms, and rough seas to the Hawaiian islands and
adjacent coastal waters through the rest of the week. Southerly
winds will strengthen tonight into the weekend, possibly reaching
gale-force for portions of the area by Friday. A Gale Watch has
been issued for the coastal waters around Kauai and Oahu starting
Friday morning. These strong to gale- force winds will last into
the weekend in association with a band of heavy showers and
thunderstorms pushing eastward across the forecast area.

A series of small, short to medium period west-northwest swells
will bring small surf to north and west facing shores through the
rest of the week. 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. The current swell will gradually
diminish later today before the next west-northwest swell builds
Friday into the weekend. Additionally, a small, medium period
north swell originating from Alaska Peninsula gap winds is
expected to arrive tonight and continue into the weekend.

The southerly wind direction will contribute to rough and choppy
surf along south-facing shores. These south winds will intensify
tonight into Friday, causing south shore surf to build Friday into
the weekend, likely reaching 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.

Choppy surf along east-facing shores will continue to trend
downward and remain below seasonal levels as south to southeast
winds prevail.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Saturday afternoon for Big Island East-Big
Island Interior-Big Island North-Big Island South-Big Island
Southeast-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.

High Wind Watch from 6 PM HST this evening through late Saturday
night for Central Oahu-East Honolulu-Ewa Plain-Honolulu Metro-
Kahoolawe-Kauai East-Kauai Mountains-Kauai North-Kauai South-
Kauai Southwest-Kipahulu-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.

High Wind Watch from 6 PM HST this evening through Sunday
afternoon for Big Island Summits-Haleakala Summit.

High Wind Watch from Friday morning through late Saturday night
for Big Island East-Big Island Interior-Big Island North-Big
Island South-Big Island Southeast-Kohala-Kona.

Winter Weather Advisory until 6 PM HST this evening for Big
Island Summits.

Winter Storm Watch from 6 PM HST this evening through Saturday
afternoon for Big Island Summits.

Gale Watch from 6 PM HST this evening through late Friday night
for Kauai Channel-Kauai Leeward Waters-Kauai Northwest Waters-
Kauai Windward Waters-Oahu Leeward Waters-Oahu Windward Waters.

&&

SHORT TERM UPDATE...Almanza
DISCUSSION...Bohlin
AVIATION...Evans
MARINE...Farris

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Preliminary Local Storm Report
National Weather Service Honolulu HI
900 AM HST Thu Mar 12 2026

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

0848 AM     Flash Flood      1 SSE Waialua           21.57N 158.12W
03/12/2026                   Honolulu           HI   Emergency Mngr

            Flooding at Waialua High and Intermediate
            School.

0815 AM     Flash Flood      10 NW Napili            21.07N 156.80W
03/12/2026                   Maui               HI   Emergency Mngr

            Landslide at mile marker 16.5 of Kamehameha
            V Hwy.

&&

Special Weather Statement
National Weather Service Honolulu HI
1128 AM HST Thu Mar 12 2026

HIZ003-004-029>031-122245-
Kauai North HI-Kauai East HI-Kauai Southwest HI-Kauai South HI-
Kauai Mountains HI-
1128 AM HST Thu Mar 12 2026

...STRONG THUNDERSTORMS WILL IMPACT KAUAI THROUGH 1245 PM HST...

At 1127 AM HST, Doppler radar was tracking a cluster of strong
thunderstorms 17 miles south of Hanapepe, or 27 miles southwest of
Lihue, moving northeast at 40 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Puhi, Anahola, Kilauea, Mana, Alakai Swamp Trails, Kaumakani,
Hanalei, Na Pali State Park, Omao, Barking Sands, Wainiha, North Fork
Wailua Trails, Wailua River State Park, Moloaa, Kapaa, Waimea,
Princeville, Lihue, Pakala Village, and Wailua Homesteads.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 2221 15934 2215 15930 2205 15934 2197 15933
      2188 15943 2191 15960 2189 15961 2202 15979
      2206 15979 2216 15971 2223 15956 2221 15950
      2223 15949 2222 15943 2224 15940
TIME...MOT...LOC 2127Z 213DEG 34KT 2168 15965

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

R Ballard

Preliminary Local Storm Report
National Weather Service Honolulu HI
1159 AM HST Thu Mar 12 2026

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

1106 AM     Flash Flood      2 ESE Waianae           21.44N 158.16W
03/12/2026                   Honolulu           HI   Emergency Mngr

            Road closures on Puhawai Road between
            Lualualei Homestead Road and Halona Road due
            to significant roadway flooding.

&&

Preliminary Local Storm Report
National Weather Service Honolulu HI
106 PM HST Thu Mar 12 2026

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

0105 PM     Flash Flood      1 N Kahului             20.89N 156.46W
03/12/2026                   Maui               HI   Emergency Mngr

            Hanakai Street completely closed between
            Hana Hwy and Alamaha St due to flooding.

&&

MB