266
FXHW60 PHFO 131400
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
400 AM HST Wed Aug 13 2025

.SYNOPSIS...
A high pressure ridge north of the Hawaiian Islands will bring
moderate to locally breezy trade winds today. A low level trough
will move through the region on Thursday, weakening the trades
and increasing clouds and showers through Friday. High pressure
will build back in across the region will bring a return to
moderate to locally breezy trade winds into early next week.
Another brief increase in clouds, showers and humidity levels will
develop from Sunday into Monday as another low level trough moves
westward through the islands; this system is associated with the
remnants of former Tropical Storm Ivo. Stable drying trends
return from Tuesday onward.

&&

.DISCUSSION...
Looking at the latest morning satellite imagery in the water vapor
channel, we see a narrow upper level trough with several embedded
weak upper lows in a southwest to northeast orientation just north
of the Hawaiian Islands. Infrared band satellite imagery shows
bands of shallow clouds under a stable ridge riding into the
islands on the east-northeasterly trade winds. Local radar imagery
shows only minimal shower activity this morning.

By Thursday the weather pattern changes a bit as an easterly wave
drifting in on the easterly trade winds moves from east to west
down the island chain. Trade winds will decrease and local scale
island heating will drive and expand afternoon sea breezes across
leeward areas of each island. Clouds and showers will increase
from east to west across the island chain as dynamics associated
with this passing trough lift temperature inversion heights to
around 8,000 feet through Thursday night near Maui and through
early Friday morning near Kauai. During this time period the
upper level trough lifts northward and a very stable upper ridge
moves directly over the Hawaiian Islands, decreasing clouds and
showers as large scale subsidence (downward vertical atmospheric
motions) lower temperature inversion heights to around the 5,000
to 6,000 foot elevation level by Friday afternoon. These drier
weather conditions will continue through Sunday morning.

By Sunday afternoon, yet another disturbance will move from east
to west through the islands. This trough will have slightly
different island by island impacts as deeper moisture and
dynamics are associated with the remnants of former tropical
cyclone Ivo that formed and diminished in the Eastern Pacific
basin. This trough will increase humidity levels across the state
from Sunday afternoon through Monday. Temperature inversion
heights will lift to around 8,000 to 9.000 feet elevation,
enhancing clouds and showers in a moderate trade wind weather
pattern.

A high pressure ridge will swiftly build back into the region on
Tuesday, just as the remnant trough continues on its westward
journey away from the state. This returning ridge will bring
strong stable trends with drier humidity levels, and a return to
more typical dry summer weather across the state through the
middle of next week.

&&

.AVIATION...
Moderate to locally breezy trade winds continue tonight with
mainly VFR conditions with only brief passing showers are expected.
Cloud and shower trends will increase from east to west across the
islands on Thursday as a weak disturbance drifts westward down the
island chain.

AIRMET Tango remains in effect moderate to locally breezy trades
over and immediately south through west of all island mountains.
This AIRMET may be cancelled later tonight as wind speeds
decrease.

&&

.MARINE...
A ridge north of the state is generating moderate to
locally strong trade winds across the state. A Small Craft
Advisory (SCA) remains in effect for the windier waters and
channels around Maui County and the Big Island through this
afternoon. A weak surface trough will advance westward across the
state around Thursday, resulting in a brief period of light
easterlies which may become variable in direction at times.
Moderate to locally fresh trades return Friday becoming locally
strong over the weekend.

The current south swell will continue to gradually decline today.
Background small, long period south southwest swell should fill
in Thursday keeping surf slightly below average. A couple of small,
long- period southerly swells is expected to fill by the weekend,
keeping surf heights near average into early next week, though
likely remaining below advisory level.

Surf along east facing shores will see a slight uptick later today
through Friday due to a small, medium period northeast swell.
Short period chop increases this weekend again as stronger trades
develop. Surf along north facing shores will remain tiny through
the forecast period.

&&

.FIRE WEATHER...
Weather conditions will likely remain below critical fire weather
thresholds into early next week. A low level disturbance will move
into the region from Thursday to Friday morning producing a slight
increase in clouds and showers. Another low level disturbance
associated with the remnants of former tropical cyclone Ivo will
increase humidity levels and shower trends on Sunday and Monday.
A return to lower humidity levels will develop by Tuesday as a
stable upper level ridge builds back over the island chain.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 PM HST this evening for the windier
waters and channels around Maui and the Big Island.

&&

$$

DISCUSSION...Bohlin
AVIATION...Bohlin
MARINE...Almanza
FIRE WEATHER...Bohlin