600
FXHW60 PHFO 050202
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
402 PM HST Fri Oct 4 2024

.SYNOPSIS...
Light to locally moderate trade winds are expected through the
weekend, bringing a few showers to windward areas. Afternoon sea
breezes will bring clouds and showers to leeward and interior areas.
A low aloft will destabilize the island atmosphere this weekend,
bringing the potential for some locally heavy showers and a chance
for a few thunderstorms mainly over the Big Island slopes and the
coastal waters. Expect stronger trade winds to return next week.

&&

.DISCUSSION...
A weak high north of the state will generate gentle to moderate
trade winds through the weekend with a gradual strengthening of
the trade winds expected the first half of next week. Satellite
and radar imagery is showing some scattered cumulus clouds riding
in with the moderate trade winds this afternoon, which have been
producing some light to moderate rain showers over select areas.
For tonight, fairly typical trade wind weather is expected with
some scattered showers over windward areas and isolated showers
over leeward areas.

For this weekend, the atmosphere will begin to change as an upper
level low approaches the state from the north and will likely move
over the state by Saturday night. The winds should be light
enough especially on Saturday for localized sea breezes during
the afternoon for select leeward areas, which should act as the
lifting mechanism for shower development. With upper level
temperatures cooling to around -10C over the western half of the
state by Saturday evening, we could begin to see some enhanced
shower activity over the western half of the state as early as
Saturday afternoon. With the upper level low moving over the state
around the Saturday night into Sunday time frame, the instability
will spread across the state, which should allow for periods of
locally heavy showers across the state and even the chance for a
few thunderstorms over select areas. At this time, it is difficult
to say where some of the heavier showers will be this weekend,
but the more likely areas will be over leeward areas during the
afternoon and evening periods and over windward areas during the
overnight and morning hours. Overall though, due to the limited
moisture (precipitable water values around 1.2 to 1.5 inches)
shower activity is not expected to be widespread. Many people will
likely see fair weather this weekend. But don`t be surprised if
you see some thunderstorms offshore or even an isolated heavy
shower overhead.

Trade wind speeds will increase early next week as new high
pressure to the distant northwest builds eastward. Stability will
also increase as the low aloft weakens and moves away to the
northeast. Some instability may linger through Monday, but stable
conditions should return by Tuesday.


&&

.AVIATION...
Light to moderate trades can be expected across the state through
tomorrow as the ridge of high pressure to the north weakens.
Clouds and showers will continue to favor windward and mauka
areas, particularly during the overnight to early morning hours
through tomorrow. In addition, with the lighter trade wind flow,
land and sea breezes will come into play.

Overnight tonight, land breezes will help to clear out clouds and
any showers from leeward areas. Tomorrow afternoon, sea breezes
will allow clouds to build up over select leeward interior areas
and bring a chance of showers to these areas. Some of these sea
breeze showers, along with some of the trade wind showers will
have the potential to produce heavier downpours, as an upper
level low begins to set up over the region and brings added
instability.

Brief MVFR or even IFR conditions will be possible in any heavier
downpours. Otherwise, VFR will prevail.

No AIRMETs are currently in effect, nor are any expected to be
needed today.

&&

.MARINE...
Surface high pressure northeast of the state will continue to
weaken through early this weekend and bring gentle to locally
moderate trade winds. Meanwhile, an upper level low is forecast
to drop down over the islands by late Saturday. This feature could
create enough instability to generate isolated thunderstorms for
areas mainly west of Oahu Saturday night into Sunday. Expect
trade winds to gradually strengthen Sunday into the first half of
next week as surface high pressure builds north of the state.
Winds could potentially reach Small Craft Advisory levels across
the windier waters and channels around Maui County and the Big
Island by next week Monday and last through at least mid- week.

For north facing shores, a pair of overlapping small, short period
north swells should maintain small surf in place through this
weekend. A short lived small, short to medium period northeast swell
is expected Saturday night through Sunday. This will also give east
facing shores a slight bump on Sunday. Although there is some
uncertainty on how strong the event will be, there is the potential
for the arrival of a moderate long period north- northwest swell as
early as Sunday and likely peaking next Monday, below advisory
levels for north facing shores. This swell could linger through the
middle of next week as it slowly fades.

Very little in the way of southern swell expected through Saturday
morning (translating to tiny waves). A moderate, long period
south swell is expected to slowly fill in Saturday, peak Sunday
and hold into Monday then gradually decline through the middle of
next week. This swell may boost surf along south facing shores to
near or slightly below advisory levels during its peak.


&&

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

&&

$$


DISCUSSION...Kino
AVIATION...Farris
MARINE...Thomas