Hilo, Hawaii 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

292
FXHW60 PHFO 230101
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
301 PM HST Sun Feb 22 2026

.SYNOPSIS...
Flash flooding will be possible over island interiors this
afternoon and over windward and mauka areas tonight as moist and
unstable trades build into the area. Trades then persist through
mid-week becoming increasingly stable with time.

&&

.DISCUSSION...

Cold northwest flow aloft supports moderate instability noted on
this afternoon`s soundings out of Lihue and Hilo. CAPE on the order
of 500-1000 j/kg is noted over island interiors this afternoon as
500mb temperatures have fallen to around -15C and 700-500mb lapse
rates are on the order of 7C/km. The environment through tonight
will be weakly or even neutrally forced aloft as the bulk of PV
advection already occurred yesterday. Instead, the islands reside
in a favorable thermodynamic environment that is particularly
sensitive to developing low-level convergence, namely among
emerging sea breeze boundaries this afternoon. Deep, slow- moving
convection/tstorms are therefore be possible over island for the
next couple of hours. Thunderstorms may yet develop over the
higher terrain of the Big Island this afternoon where they are
considerably less likely to result in a flash flooding threat.

Trades then return tonight as the environment remains weakly forced
overall. The mechanism for low-level convergence will shift to
terrain and will therefore refocus the flash flooding threat over
windward and mauka zones for tonight. Trades will gradually
strengthen, becoming breezy by early morning Wednesday which will
lead to decreasing convergence and increasingly progressive shower
motion with time. However, at least the first half of the night will
see rather slowly building trade winds and correspondingly slow-
moving convection embedded within. The Flood Watch therefore
remains in effect for for Kauai, Oahu, Molokai, and Maui.

Mid-level ridging gradually builds as the week progresses leading to
increasingly stable trades.

&&

.AVIATION...

A few SHRA and some isol TSTMS are ongoing across mostly Maui and
the Big Island this afternoon. The trough that moved north is
expected to move back southward through the state tonight and
tomorrow, bringing another round of SHRA and TSTMS with a return
of breezy and gusty trade winds. IFR/MVFR conds possible within
SHRA, otherwise VFR should prevail.

AIRMET Sierra is not in effect at this time but may be needed
later tonight as the trough moves southward.

AIRMET Tango remains in effect for mod upper level turb across
the entire state.

&&

.MARINE...

A trough stretching from a surface low north of Maui across Oahu
to south of Kauai will produce gentle westerly winds south of the
trough, while fresh to strong easterly winds prevail north of the
trough. Scattered heavy showers and isolated thunderstorms can be
expected near the trough. The trough will be pushed slowly
southward by a strong North Pacific surface high tonight and
Monday. Fresh to strong trade winds north of the trough will
spread over waters north of the Big Island, with the strongest
winds initially around Kauai and Oahu requiring a Small Craft
Advisory (SCA). Winds should ease slightly Monday night and
Tuesday, but a large north-northeast swell will produce seas in
excess of the 10 foot SCA threshold over most waters into Tuesday
night. Moderate to locally fresh trades are expected on Wednesday,
giving way to southeasterly winds Thursday or Friday as a front
approaches.

Very small surf will persist across most shores through tonight,
followed by a building north-northeast (010-030 deg) swell on
Monday. This long period swell will build rapidly during the
afternoon and will produce breaking waves at High Surf Warning
levels across most north and east facing shores during the peak
Monday night and Tuesday. Due to the direction of the large swell,
exposed west facing shores of West Maui, western Molokai, and
North Kohala on the Big Island will likely experience High Surf
Advisory waves. A Coastal Hazard Message has been issued to
highlight these conditions. The north-northeast swell will
gradually decline Tuesday night through Friday. In addition to
this swell, a small pulse of overlapping west-northwest swell is
expected Monday through Wednesday.

Due to the direction of the large north-northeast (010-030)
swell, some overwash will be possible along low-lying coastal
roads and infrastructure in windward areas, and hazardous
conditions and heavy surges are expected in north facing harbors,
mainly in Hilo and Kahului. A Marine Weather Statement has been
issued to highlight this threat.

Very small wintertime surf will continue along south facing
shores this week.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Flood Watch through late tonight 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-Haleakala Summit-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.

High Surf Warning from noon Monday to 6 PM HST Tuesday for
Niihau-Oahu North Shore-Olomana-Maui Windward West-Kauai North-
Kauai East-Koolau Windward-Molokai Windward-Molokai North-Maui
Central Valley North-Windward Haleakala-Big Island East-Big
Island North.

High Surf Advisory from 6 PM Monday to 6 PM HST Tuesday for Maui
Leeward West-Kohala-Molokai West-Lanai Windward.

High Wind Warning until 6 AM HST Monday for Big Island Summits.

Small Craft Advisory from 6 PM this evening to 6 PM HST Tuesday
for Kauai Northwest Waters-Kauai Windward Waters-Kauai Leeward
Waters-Kauai Channel.

Small Craft Advisory from 6 AM Monday to 6 PM HST Tuesday for
Oahu Windward Waters-Kaiwi Channel-Maui County Windward Waters-
Alenuihaha Channel-Big Island Windward Waters.


&&

$$


DISCUSSION...JVC
AVIATION...Walsh
MARINE...Wroe