085
FXHW60 PHFO 250704
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
904 PM HST Tue Sep 24 2024

.SYNOPSIS...
Gentle to breezy east trade winds will continue the next several
days. Rainfall will be limited with more cloudiness and brief
showers favoring windward exposures and higher terrain. The lone
exception will be along Kona region slopes of Big Island where
thicker cloud cover and showers will develop during daytime
hours.


&&

.DISCUSSION...
A partly to mostly cloudy end to the day in paradise as cirrus
debris clouds from thunderstorms far south of Hawaii (riding 10N
latitude) race up within upper level southerlies primarily over
the western half of the state while lower level stratocumulus move
in from the east in the lower level trade belt. A large ridge of
high pressure orientated parallel to the middle latitudes is this
week`s main Central Pacific synoptic scale feature. The pressure
gradient from the associated 1022 mb surface high centered between
30N and 40N latitude and along 150W longitude will continue to be
the driver of gentle interior and breezy coastal and mauka east
trades into October. Low pressure moving east across the Gulf of
Alaska will ride atop this ridging and nudge it slightly closer to
the island chain. Overall, this will have little to no effect on
these ongoing gentle to breezy east trades the next several days.
The only subtle effect would be a minor slackening of the gradient
that could result in a hardly noticeable weakening of late week
easterlies to more gentle magnitudes. The low will progressively
move far northeast of the region this weekend, allowing the ridge
to rebound to the north. This will likely correlate to the return
of more statewide breezy east trades early next week.

Mid to upper level ridging will build in over and north of the
islands during the remainder of the week. This will translate to
clearing out skies and result in a relatively drier weather
pattern. Brief shower activity will favor windward areas and
higher elevations, especially during the nocturnal hours.


&&

.AVIATION...
Moderate to locally breezy trade winds will continue due to high
pressure to the north of the area. Upper level high pressure
moving over the islands from the east will maintain a stable
airmass during this time. Limited clouds and showers will be
carried in on the trade winds, focusing what few showers make it
to windward sides of the islands. Some afternoon clouds and
showers are possible over the Kona slopes of the Big Island. VFR
conditions are expected to prevail.

No AIRMETs are currently in effect and none are anticipated at this
time.


&&

.MARINE...
High pressure far north of the state will maintain moderate to
locally strong trade winds through Wednesday afternoon. A Small
Craft Advisory (SCA) remains in effect for the typical windy
waters around Maui County and the Big Island during this time.
Latest high resolution model data then shows conditions becoming
borderline as the high fluctuates in strengthen through the rest
of the week. Will continue to monitor latest observations
overnight to see if conditions warrant an extension of the SCA.
Global models have been trending towards a gentle to fresh
tradewinds pattern developing over the weekend as a front passes
far north of the state weakening the high far northeast of the
area. Moderate to locally strong trades may rebound early next
week as the front dissipates and a new high quickly rebuilds north
of the state. For the offshore waters, a trough located far SW of
the state will bring a slight chance of thunderstorms over the
west and SW waters through tonight.

A moderate long period northwest swell (320 to 330 degrees) filled
in throughout the day today and should peak tonight then steadily
decline the rest of the work week. Buoy 51001 and 51101 northwest of
Kauai showed a peak swell height of around 6 to 7 feet 16 seconds
earlier today. This should translate to surf peaking below advisory
thresholds tonight for north facing shores of Kauai and Oahu. A
smaller north-northwest swell should provide a boost this weekend.

Surf along south facing shores will see a few pulses of small
long-period southwest through the weekend from series of storms
near the Tasman Sea last week. The first pulse appears to be
peaking this evening based on latest reading from nearshore buoy
readings. Another smaller long-period southwest swell is possible
Friday slowly declining over the weekend with yet another small
southwest pulse late Sunday. Additionally, a fetch of strong
southwest winds near 10N170W yesterday should bring an increase of
short-period energy from the southwest Wednesday into Thursday.
East facing shores should remain small through much of the week
and into the weekend due to the lack of strong trades locally or
upstream of the state.


&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 PM HST Wednesday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big
Island Southeast Waters.


&&

$$


DISCUSSION...Blood
AVIATION...M Ballard
MARINE...Almanza