Kaiona Beach Park, Hawaii Weather Forecast Discussion

907
FXHW60 PHFO 160130
AFDHFO
Area Forecast Discussion
National Weather Service Honolulu HI
330 PM HST Mon Sep 15 2025
.SYNOPSIS...
Locally breezy trades deliver limited clouds and showers windward
and mauka through Thursday. An increase in showers, particularly
during the overnight hours, is then anticipated for the weekend.
&&
.DISCUSSION...
Little to note on regional visible imagery this afternoon as
locally breezy trades focus fairly stable low clouds windward and
and mauka. A handful of sites located on Windward Big Island and
Maui have observed less than a 0.05" of rainfall with nothing
recorded elsewhere. No substantial change to sensible wx
conditions expected into Friday given lack of an upstream moisture
source and continued dry advection centered at 700mb in
maintenance of the existing inversion.
Focus for the weekend turns to the cold front draped roughly along
35N north of the islands. The tail end of the front will be
pinched off by building high pressure allowing a narrow ribbon of
moisture to become entrained in prevailing trades. Friday night
and Saturday night are poised to see a noteworthy uptick in
windward and mauka showers which will likely drift leeward at
times. Forecast soundings indicate modest cooling aloft, mainly
over the western end of the state, supporting adequate but not
impressive lapse rates approaching 6.5C/km. Deep moisture likely
weakens and lifts the inversion to 10kft or higher with any
pockets of particularly deep moisture potentially capitalizing on
modest conditional instability. This sets the stage for a few
embedded heavier showers. Stout trades ensure any moderate to
heavy showers remain progressive.
&&
.AVIATION...
Moderate to locally breezy trade winds will continue through
Tuesday. Limited clouds and showers will favor windward and mauka
areas, with a slight uptick during the overnight hours. VFR
conditions will generally prevail, with brief MVFR possible with
passing showers.
No AIRMETS are in effect and none are anticipated through the
forecast period.
&&
.MARINE...
Weak high pressure north of the state will become reestablished by
midweek. This will result in small fluctuations of trade wind
speeds across the coastal waters for the next several days, but
they will generally remain in the moderate to locally strong
range. Although an ASCAT pass earlier today did not indicate Small
Craft Advisory (SCA) level winds at this time, the SCA that is
currently in effect for the windier channels and waters around
Maui and the Big Island has been extended through Wednesday
afternoon based on the latest hi-res guidance.
Small surf this evening along north facing shores will decline to
tiny levels tonight into Tuesday as the recent northwest swell
fades. North shore surf will hold at tiny levels for several days
thereafter. A gale low that is currently in the Gulf of Alaska is
expected to send a minor north swell towards Hawaii later this
week, resulting in a small bump in surf heights for north facing
beaches beginning on Thursday. An additional small northwest
reinforcement is expected this weekend.
The current small, medium period south swell will gradually
decline through mid-week. A couple of very small reinforcements
are expected throughout the next several days, though surf will
remain small. A slightly larger long period swell, generated from
gales and near-gales aimed at Hawaii this past weekend near New
Zealand, is forecast to arrive in the islands by Friday night.
This swell will boost south shore surf back up to near the
September average this weekend.
East facing shores will experience typical trade wind generated
energy throughout the forecast period.
&&
.FIRE WEATHER...
Humidity gradually increases through the week as sustained winds
briefly hover near to below the critical fire weather threshold
each afternoon. Showers remain rather sparse in coverage until the
weekend.
&&
.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...JVC
AVIATION...Farris
MARINE...Vaughan
FIRE WEATHER...JVC

NWS HFO Office Area Forecast Discussion