Waianae, Hawaii 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

257
FXHW60 PHFO 250138
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
338 PM HST Sat May 24 2025

.SYNOPSIS...
Moderate to locally breezy trades will persist through Sunday,
then gradually ease next week as the high to the far NW of the
island chain weakens. As an upper level low pushes away from the
state, mid level ridging and drier air filtering in on the trades
will limit shower activity through much of next week.

&&

.DISCUSSION...
In a nutshell, increasing atmospheric stability and limited
moisture will bring a drier trade wind pattern through next week.

Now for the details...

At the surface, a strong high to the far northwest of the state
and a weaker high to the far east-northeast are separated by a
northeast-to-southwest oriented front heading eastward towards
the West Coast of the mainland. This pair of highs will continue
to bring moderate to locally breezy trade winds to the island
chain through this weekend. As a broad low develops to the distant
northeast early next week, it will weaken the high to the
northwest, relax the local pressure gradient, and bring lighter
trade winds to the area. This weaker flow will persist through
much of next week and may allow for sea breeze development across
some leeward areas, increasing clouds and bringing a slight chance
of rain.

Looking aloft, the upper level low that`s been responsible for
enhancing tradewind showers over the last day or two will
gradually push eastward and away from the state over the next
couple of days, with mid level ridging building overhead in its
wake. As 500 mb heights and temperatures rise, atmospheric
stability will increase over the region, helping to lower and
strengthen the low level inversion and put a lid on some of the
shower activity, confining most trade wind showers to windward and
mauka areas through early next week. In addition, low level
moisture will be limited with drier air filtering in on the
trades, also helping to limit shower activity. A weak upper
level trough/low will develop near the northwestern end of the
state midweek, and sweep across the state on Wednesday. While this
feature will introduce some instability aloft, moisture will still
be limited, so not expecting it to cause much of an uptick in
showers at this time. A strong mid level ridge will quickly build
overhead in its wake, bringing more dry and stable conditions
through the rest of the week.

&&

.AVIATION...
As the upper low continues to move away from the island chain,
drier air and a seasonal trade wind pattern will keep showers
mostly along windward and mountain areas. VFR conditions will
prevail over most locations, with only isolated MVFR conditions
over the windward side of the Big Island.

There are no AIRMETs in effect.

&&

.MARINE...
An area of high pressure centered to the distant north-northwest
of the main Hawaiian Islands will provide a brief stint of
moderate to locally strong trade winds through Sunday afternoon.
Based on the latest hi-res guidance, a Small Craft Advisory has
been issued for the typically windy waters of Maui County and
around the Big Island. This SCA will be in effect through Sunday
afternoon, then trades will ease back into the moderate to fresh
range as the high pressure to the NW gradually weakens through
mid-week.

A small long period south-southwest swell moving through the
islands is peaking today and will then gradually decline through
early next week. A similarly-sized long-period south-southwest
swell is expected to arrive Wednesday into Thursday, bringing
another boost to south shore surf.

East shore surf will remain near seasonal average through the rest
of the weekend as trade winds persist, then gradually decline
through mid-week as the trades weaken slightly. Surf along north
facing shores will remain tiny through the next several days. A
surface low near the Aleutians this weekend is expected to send a
small, medium period north-northwest swell towards the islands
during the later half of next week.

Through Wednesday, it is possible that higher than normal tides
could lead to some coastal flooding during the peak of high tides
in the early afternoon hours. However, since the elevated tides
are generally expected between the aforementioned south swells,
this event should have minimal impacts.

&&

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

&&

$$

DISCUSSION...Farris
AVIATION...Ahue
MARINE...Vaughan