Waihee-Waiehu, Hawaii 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

710
FXHW60 PHFO 231356
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
356 AM HST Tue Dec 23 2025

.SYNOPSIS...
An old remnant frontal boundary moves swiftly through the islands
today with a brief boost in showers and breezy trade winds.
Easterly trade winds will quickly decrease tonight through
Wednesday with a hybrid light to moderate east-southeasterly wind
and sea breeze pattern setting up over the islands from Wednesday
night through the Christmas holiday weekend. Shower activity will
be limited from Wednesday onward after the remnant cloud band
passes through the state. An approaching upper level disturbance
on Sunday will spread significant high level cirrus clouds from
west to east across the region. This upper disturbance will
increase statewide shower trends in a light southeasterly wind
pattern for the first half of next week.

&&

.DISCUSSION...
In the big picture satellite imagery, we see a high pressure
ridge in place north to northeast of the Hawaiian Islands, a
deep low and cold front far northwest of the state tracking
northeastward,and a narrow low level cloud band drifting through
the islands this morning. Breezy trade winds will push this narrow
remnant cloud band through the islands today enhancing shower
trends for all islands, especially over the typical windward
mountain slopes.

The cold front trailing the low northwest of the islands will
approach the Hawaii region from the west and stall long before
reaching the western most island of Kauai. However, the main
impact to island weather will be a change in wind directions as
the high pressure system far north of the state drifts east,
parking a low level ridge directly over the island chain. Wind
speeds will weaken and veer more from a east to southeast
direction from Wednesday night through the Christmas holiday
weekend. Another impact of this ridge over the state will be felt
in the large scale subsidence, or stabilizing downward vertical
motions that will warm and dry the air over each island.
Subsidence temperature inversion heights will lower, decreasing
vertical cloud growth and keeping shower activity to minimum
during this time period. Only brief passing showers remain in the
forecast and any rainfall amounts will be light. American model
(GFS) cross sections show this trend well with temperature
inversion heights hovering around 5,000 to 6,000 feet elevation
from Wednesday night into Sunday.

By early next week, another shallow cold front approaches Kauai
from the northwest. The latest model consensus guidance suggests
this weak frontal trough will stall out long before reaching the
islands. However, a more interesting pattern is brewing in the
upper levels as a passing and strong upper level trough will
deepen into an upper low near the islands. Extended range weather
model solutions project this upper low to pass from west to east
across the entire state during this time period. If this long
range solution works out as predicted, then all islands will see
rain shower enhancement in a light wind sea breeze wind pattern.
Rainfall activity will favor island mountain and interior sections
with decent rainfall potential for even the normally drier
leeward sections. Stay tuned as this extended range forecast
period will certainly evolve over time.

&&

.AVIATION...
An old remnant frontal boundary moves swiftly through the islands
today with a brief boost in breezy trade winds. Easterly trade
winds will quickly decrease tonight with a hybrid light to
moderate east-southeasterly wind and sea breeze pattern setting
up over the islands with decreasing shower trends from Wednesday
night onward.

AIRMET Sierra has been posted for tempo mountain obscurations
for all islands as this low level cloud band passes swiftly
through the islands. This AIRMET will likely be trimmed down in
coverage for some islands later today as more stable air moves in
from the northeast.

AIRMET Tango remains in effect for tempo moderate turbulence
downwind of terrain on all islands below 8000 feet will likely
continue through tonight.

&&

.MARINE...
Surface high pressure far north-northwest of the waters will
drift east through Wednesday as low pressure far to the northwest
of Kauai remains nearly stationary and weakens. Easterly trade
winds will strengthen over majority of the coastal zones today
into the fresh to strong range as the Small Craft Advisory (SCA)
has been extended through tonight due to a combination of winds
and seas. The SCA will be trimmed to the windier waters and
channels around Maui County and the Big Island Wednesday. The
high pressure north of the waters will weaken as it passes north
of Hawaii on Wednesday, coinciding with the weakening low, thus
gradually weakening the winds and veering to the southeast to
south by the end of the week. Area of low pressure looks to
redevelop and push a surface ridge near Kauai by the weekend.

The current small north swell will continue to gradually decline
into Wednesday. A moderate, medium period north-northeast (010-030
degrees) swell will arrive late Wednesday and peak Thursday and
Friday. Surf along north facing shores could approach the High
Surf Advisory level during the peak, with the largest swells
favoring the eastern end of the island chain, and a Marine Weather
Statement will likely be needed tonight for harbor surges at
Kahului and Hilo. The north swell will decline over the weekend as
a small northwest swell arrives.

Surf along east facing shores have increased overnight coinciding
with the short period energy from the building trade wind energy.
Strong trades will produce rough and choppy conditions through
Wednesday, mainly over the western islands, peaking near or
briefly at High Surf Advisory levels for east facing shores before
declining. Short period trade wind swell will decline by
Christmas, but wrapping northerly swell will affect exposed
eastern shores into Friday. Surf along south facing shores will
remain very small through the week.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 AM HST Wednesday for most Hawaiian
Coastal Waters due to a combination of winds and seas.

&&

$$

DISCUSSION...Bohlin
AVIATION...Bohlin
MARINE...Shigesato