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Hawaiian Islands Synoptic Discussion and Guidance

682
FXHW60 PHFO 251949
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
949 AM HST Sat May 25 2024

.SYNOPSIS...
Broad high pressure north and northeast of the state will
maintain moderate to locally breezy easterly trade winds through
the week. Showers will mainly favor windward slopes, and batches
of high clouds will pass overhead at times.

&&

.DISCUSSION...
Moderate to locally breezy easterly trade winds remain in place.
The trades are being driven by broad surface high pressure sitting
roughly 1400 miles north of the state, and a surface trough parked
about 600 miles west of Kauai is causing the winds to be more
easterly than usual, especially over the western end of the island
chain. Mid-level ridging over the islands is maintaining somewhat
stable conditions, and shallow moisture moving along the trade
wind flow will focus modest rainfall of around a quarter of an
inch per day across most windward slopes. An upper-level trough
generally collocated with the surface trough is producing
thunderstorms about 200 miles west of Kauai, and westerly winds
aloft are carrying thin high clouds over the state. Thunderstorm
activity will remain west of the state through the holiday
weekend, but the inversion will could be weakened at times near
Kauai, where brief periods of enhanced showers will be possible.
In addition, expect spotty afternoon and evening showers, some
briefly heavy, across leeward Big Island.

Little change is expected Tuesday onward. The surface high will
settle far northeast of the state and hold into Friday, and the
surface trough will linger west of the islands, resulting in
breezy easterly trade winds. The nearby upper-level trough will
weaken, suggesting grater stability and supporting a typical
rainfall pattern with showers continuing to favor windward
slopes.

&&

.AVIATION...
Moderate to locally breezy trade winds will prevail across the
Hawaiian Islands for the next several days. As a result, AIRMET
Tango remains in effect for moderate low-level turbulence downwind
of island terrain. This AIRMET will likely remain in effect
though much of next week.

A fairly stable pattern will remain over the state into next week.
However, passing showers will favor north through southeast
sections of the islands, with greater coverage expected during the
overnight hours each night. While VFR conditions will prevail
over most locations, brief MVFR ceilings and visibilities will be
possible as showers move through.

&&

.MARINE...
High pressure north of the state will maintain moderate to locally
strong easterly trade winds across the state through the first
half of next week. A Small Craft Advisory (SCA) remains in effect
for the windiest waters around Maui and the Big Island through 6AM
Sunday. A trough will amplify and linger west of the islands
Sunday through the middle of next week, resulting in a shift to a
more east-southeast direction over the western end of the state.
This will allow the trades to ease slightly over the leeward
waters of Kauai and Oahu. Moderate to locally strong easterly
trades will continue to prevail elsewhere across the state.

South shore surf will remain small and below the summer average
through the middle of next week, with only small pulses from the
southeast and southwest. The next significant south-southwest
swell (200 degrees) appears to move in toward the end of next
week. East shore surf will decrease slightly this weekend then
hold steady through late next week. Surf along north shores will
remain very small with a slight bump possible late Sunday through
Monday.

&&

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

&&

$$


DISCUSSION...Wroe
AVIATION...Vaughan
MARINE...Kino

Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office