Waihee-Waiehu, Hawaii 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

430
FXHW60 PHFO 141336
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
336 AM HST Thu Aug 14 2025

.SYNOPSIS...
A low level trough will move through the region today, weakening
the trades and increasing clouds and showers through Friday
morning. High pressure will build back in across the region from
Friday into early Sunday, bringing a return to moderate to
locally breezy trade winds. Another brief increase in clouds,
showers and humidity levels will develop from Sunday afternoon
through Monday as another low level trough moves westward through
the islands; this system is associated with the remnants of former
tropical cyclone Ivo. Stable drying trends return from Tuesday
onward.

&&

.DISCUSSION...
Water vapor imagery early this morning shows a weak elongated
trough stretching southwest to northeast across the island chain.
A combination of local radar and infra-red satellite imagery
shows scattered showers moving into the islands with the trades,
favoring windward areas. Some isolated showers have drifted over
the leeward terrain on the smaller islands. However, overnight
rainfall totals are generally unimpressive, less than 0.05 of an
inch.

A low level trough will move through the islands from west to
east today. The passage of this trough will help weaken trades
and transition us into a hybrid sea breeze pattern. In addition,
this subtle feature will act to deepen the inversion heights into
the 7,000 to 8,000 foot range and bring a slight uptick in
showers along windward locations this morning with additional
diurnal driven development over leeward terrain by this afternoon.
Model derived Showalter index depicts enough instability to add
isolated thunderstorms to interior portions of the Big Island
later this afternoon.

By Friday, a surface ridge will build north of the Hawaiian
Islands, allowing moderate to locally breezy trades to return.
Drier air will filter in from the east as a very stable upper
level ridge nudges its way back over the state. As inversion
heights lower, cloud cover and shower activity will wane with only
isolated windward showers expected 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. Our confidence in this brief period of enhanced shower
activity is only fair at this time. Typically these remnant
tropical systems tend to be compact in size and may possibly track
a bit further north than currently predicted by our global
weather models. If this system does move further north of track,
then our current weather forecast will change, resulting in less
clouds and showers reaching the Hawaiian Islands. Stay tuned.

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...
Cloud and shower trends will increase from east to west across the
islands today as a weak disturbance drifts westward down the
island chain. Mostly VFR conditions will prevail, with brief
periods of MVFR conditions possible in passing showers.

No AIRMETs in effect.

&&

.MARINE...
Surface trough moving westward north of the waters will keep
light to locally moderate flow through the day. Trade winds will
gradually strengthen Friday into the weekend as the high builds
north of the state. A Small Craft Advisory for the windier waters
and channels around Maui County and the Big Island could start as
early as Friday morning and hold through the weekend.

Surf along south facing shores will remain small through tonight
with mainly background medium to long period energy. Surf should
see a slight bump early Friday and hold through early next week as
a series of small long period southerly energy fills in.

A small, medium period northeast swell has filled in and will keep
surf along east facing shores elevated through the weekend. As
this swell declines, the short period energy will fill in as trade
winds increase into the weekend. North facing shores will remain
flat to tiny through the forecast period except for areas that
may be exposed to the small northeast swell.

&&

.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 today through Friday morning producing a
slight increase in clouds and showers. Another low level
disturbance associated with the remnants of former tropical
cyclone Ivo will likely 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...
None.

&&

$$

DISCUSSION...Thomas/Bohlin
AVIATION...Thomas/Bohlin
MARINE...Shigesato
FIRE WEATHER...Thomas/Bohlin