114
FXHW60 PHFO 210634
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
834 PM HST Thu Aug 20 2026

.SYNOPSIS...
Trades remain weak through Friday as a trough advances north of
the islands. Tropical Depression 2C has formed southeast of Hawaii
and is forecast to track south of the area early next week
bringing strengthening winds and potential for heavy rainfall,
especially to the eastern end of the state.

&&

.SHORT TERM UPDATE...
Main update to the forecast this evening was to increase shower
chances across the islands for the next few hours. Radar imagery at
8 PM HST was showing areas of light showers moving across portions
of the state. Showers are expected to become more confined to the
Big Island and east Maui overnight. Periods of light showers are
expected to continue through the day Friday with light showers
possible over leeward areas. We`re continuing to monitoring the
track and how Tropical Depression Two-C evolves.

&&

.PREV DISCUSSION...
Issued at 313 PM HST Thu Aug 20 2026

Surface troughing associated with tropical remnants positioned
immediately north of the Hawaiian islands will advance NW during the
next 24 hours. This will substantially weaken the gradient leading
to very light winds, expanding sea breezes, and muggy weather with
dewpoints in the low 70s. A few afternoon showers over leeward areas
will be possible today and tomorrow with light trades delivering
limited showers windward overnight.

NHC maintains a track well south of the islands for Tropical
Depression 2C, although even this track is firmly on the northern
edge of the guidance envelope. Confidence is increasing that the
primary impacts from this system will be strengthening trade winds
and heavy rain potential over southeast & portions of windward Big
Island. At this time, it appears that breezy trades return Saturday
into Sunday as resident surface troughing lifts away from the area
and TD 2C lifts NW out of the deep tropics. Trades then strengthen
considerably as the gradient responds to the close proximity of the
tropical system and 1022mb high pressure anchored along 30N. Sunday
may be quite windy over the eastern end of the state with strong
trades spreading westward to the remainder of the state Sunday night
through Monday. Wind headlines are probable during this time, and a
High Wind Watch for the windier areas of Maui County and the Big
Island can`t be ruled out. It is not out of the question that a
portion of the area may instead be under tropical watches/warnings
during this time - this remains to be seen.

The lower latitude origin of TD 2C will lend itself to a more robust
plume of trailing moisture extending from the NE side of the system
well to the SE. This establishes a rather broad area of potential
heavy rain that could impact the Big Island mainly Sunday and Sunday
night, but potentially continuing through Monday if the system
tracks further north. The rainfall forecast remains highly track
dependent and any northward adjustment will increase the probability
of and magnitude of heavy rain for the Big Island. At this time, the
official rainfall forecast has been trended downward to account for
the latest trends, but still allows for around 10" of rainfall,
locally higher, over the Puna and Ka`u Districts and, to a lesser
extent, the Hilo Districts of the Big Island. Rainfall over the
smaller islands is considerably less certain with a more northerly
track potentially producing a widespread 1-4" while a more southerly
track may leave the smaller islands relatively dry and in a more
typical windy trade wind type of pattern. Stable, breezy trades
establish for the remainder of next week as the tropical system
departs and governing high pressure centered along 30N remains in
place.

&&

.AVIATION...

A surface trough will continue to move from east to west through
the western end of the islands chain overnight and allow for weak
trade wind flow. Thus, low clouds and mainly isolated light
showers area expected along the windward coasts. VFR conditions
are expected to prevail, except those pockets of MVFR in clouds
and showers. Trades will begin to fill back in tomorrow morning,
strengthening first across the Big Island and Maui during the
morning, then across the remaining smaller islands by the
afternoon.

No AIRMETs are currently in effect, and none are expected through
Friday night.


&&

.MARINE...

A trough just north of the islands will track northwestward
across the offshore waters, leading to a period of light and
variable winds for most waters through tonight. By late Friday,
moderate to locally fresh trades will begin to build back into the
region as the trough exits to the northwest, high pressure drifts
southward closer to the island chain, and Tropical Depression
Two-C nears the state from the southeast. The forecast for this
weekend will depend on the track of this tropical cyclone, but
overall the trade winds are expected to strengthen with gale force
winds possible over the windier channels of Maui and the Big
Island around Sunday.

Surf along south facing shores will remain slightly below average
through at least Friday morning. A long period south-southwest
swell generated from gales just south and east of New Zealand is
beginning to trickle in this evening, and is expected to provide
a slight bump in surf heights, possibly becoming near average by
Saturday. Surf along east-facing shores remains below average with
weak trades, then is expected to build this weekend as the trades
restrengthen. Surf along east and south-facing shores will be
compounded by a southeast swell generated by Tropical Depression
Two-C that will build through Sunday and then become south, then
southwest through early next week. This short-period tropical
swell could cause surf to approach advisory levels along east
facing shores of the Big Island Saturday night into Sunday, though
forecast confidence is on the lower side as the wind field with
this tropical cyclone is expected to be relatively small and the
forecast track may shift slightly. North facing shores will remain
tiny through Friday, with a slight bump from Hurricane Lala
possible this weekend out of the west-northwest direction.


&&

.HFO WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE...CO
DISCUSSION/FIRE WEATHER...JVC
AVIATION...Thomas
MARINE...Kino