824
FXHW60 PHFO 061348
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
348 AM HST Tue Oct 6 2026

.SYNOPSIS...

Gentle to locally breezy trades will hold through today. Winds
will begin to turn out of the south by tonight into Wednesday as
an area of low pressure develops to the north of the state.
Chances for rain and the potential isolated thunderstorm and
locally heavy rain increases Wednesday night through the rest of
the week.


&&

.DISCUSSION...

Current radar and satellite imagery show isolated to scattered
light to brief moderate showers moving into windward and mauka
areas of the state on the gentle to locally breezy trades this
morning. The high driving our trades has shifted slightly more
northeast overnight allowing trade winds to ease a notch or two
overnight. An upper level trough will start to dig south
Northwest of the state today through Wednesday. This will
continue to weaken the trade wind flow, allowing for a hybrid
lighter trade wind and sea breeze pattern to develop this
afternoon, generating clouds and a few showers over mauka and
interior areas.

The trough to the northwest will deepen enough form a broad
cutoff low both aloft and at the surface by Wednesday night into
Thursday north of Kauai, causing the low level flow to veer out
of the south across the state. With increasing instability aloft
due to the nearby low and deep tropical moisture being advected
northward in the southerly flow, the potential for heavy rain will
increase beginning Wednesday afternoon and persist through at
least Friday as a rainband associated with the low meanders across
the state. In this flow, the potential heavy showers will likely
favor south- facing portions of each island. The forecast has been
updated to include isolated thunderstorms Wednesday night into
Thursday as a shortwave trough within the deepening low swings
slightly further south, increasing instability over the state.
Current rainfall forecast is on the higher end of guidance but
confidence is low as it will be highly dependent on where the
associated rainband sets up across the state and the intensity of
showers within the band. So far the high intensity showers appears
to be isolated and brief. Thus holding off on a Flood Watch for
now.

Beyond Friday, forecast confidence decreases significantly as
the global deterministic model solutions diverge. ECMWF brings
tradewinds in earlier, breaking up and pushing the rainband west
of the state. GFS has the rainband remaining fairly broad across
the state. Impacts will rely heavily on where this rainband set up
and for how long. However, the ensembles continue to lean toward
bringing trades back on Saturday into Sunday, so the forecast
remains nudged toward the ECMWF solution.


&&

.AVIATION...
Background trade winds will be weaker today, then continue to
weaken and veer more southerly tonight into Wednesday due to a
nearby surface trough. This will cause a hybrid light trade wind
and sea breeze pattern. Terrain sheltered areas will be more
likely to see afternoon cloud and shower development as a result.
Meanwhile, brief and isolated shower activity is expected over
windward and mountain areas. MVFR conditions will occur within
showers, while VFR prevails elsewhere.

There are currently no AIRMETs in effect, though mountain
obscuration could become an issue for portions of the state later
today.


&&

.MARINE...
High pressure centered far northeast of Hawaii will drive
moderate to locally fresh trade winds today. Winds will continue
to weaken as a low pressure system develops north of the state and
a trough extending from this low is forecast to move into the
northwest offshore waters by Thursday. The low will stall north
of the islands and draw moisture out of the tropics and over the
area through the second half of the week, so expect an increase in
showers with moderate south to southeast winds.

Offshore buoy observations show a southerly swell around 3.5 ft with
16 second period, which will push surf for south-facing shores close
to advisory level by this afternoon and last through tonight. By
Wednesday, this swell will begin to fade. Surf is then likely to be
held near seasonal averages for the remainder of the week, maintained
by a mix of new, small south swells.

A long-period northwest swell will arrive today, pushing surf for
north-facing shores up tonight to near moderate levels on Wednesday.
Small to moderate surf is then forecast through the rest of the week
even as swell energy becomes shorter period, since it will be
reinforced by a low to the north-northwest of the Hawaiian Islands.
Surf along east facing shores will remain small as local winds remain
fairly weak.

A small, long-period west swell originating from Typhoon Choi-wan
is forecast to reach the islands Thursday into the weekend, which may
produce moderate surf for west-facing shores.


&&

.FIRE WEATHER...

Gentle to locally breezy trades will hold through today with RH
values just above the critical threshold for fire weather during
the afternoon hours. Fire weather risk then diminishes through the
remainder of the week as moisture increases, winds remain light to
moderate, and showers increase in coverage. The inversion should
range from 6 kft to 8 kft through today and deteriorate Wednesday
afternoon.


&&

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

&&

$$

DISCUSSION...Almanza
AVIATION...Vaughan
MARINE...Quesada