909
FXHW60 PHFO 041300
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
300 AM HST Tue Jun 4 2024

.SYNOPSIS...
Breezy trades will continue today, before easing Wednesday and
giving way to sea and land breezes Thursday and Friday. A fairly
typical trade wind pattern will continue this morning, with trade
wind showers then steadily decreasing through the middle of the
week as a more stable airmass gradually settles overhead. Some
lingering instability may allow for a thunderstorm to pop over
interior Big Island this afternoon however. Very dry conditions
will overspread the entire island chain Thursday through the
weekend, greatly limiting shower activity. Returning and gradually
strengthening trade winds could bring a slight increase in
showers early next week.

&&

.DISCUSSION...
Currently at the surface, a 1025 mb high centered 950 miles
northeast of Honolulu, is driving breezy trade winds across the
island chain. Infrared satellite imagery shows partly to mostly
cloudy conditions with cloud cover most prevalent over windward
and mauka areas. Radar imagery shows isolated to scattered showers
affecting windward slopes and coasts, with the occasional shower
spilling leeward. Main short term focus revolves around trade
wind trends and rain chances.

The high to the northeast of the islands will remain nearly
stationary today, slowly weaken as it shifts eastward on
Wednesday, with the ridge axis then moving over or very near the
western islands Thursday and Friday. Breezy trade winds will
continue today, then ease into the moderate range Wednesday. The
winds will ease further and become light and variable over the
smaller islands Thursday and Friday, allowing for daytime sea
breezes and overnight land breezes to be dominant. Meanwhile,
light trades will likely hold in the unprotected areas of the Big
Island. The surface ridge axis is forecast to shift northward over
the weekend into early next week, which should bring a return and
gradual strengthening of the trade winds.

As for the remaining weather details, isolated to scattered
windward showers should prevail this morning, with the trade wind
inversion then expected to lower to around 5 kft greatly limiting
trade wind showers this afternoon. There remains a slight chance
that instability aloft could allow a thunderstorm to pop over the
Big Island interior this afternoon as well.

Rather dry trade wind weather will continue tonight through
Wednesday night as the trade wind inversion holds around 5 kft,
with most leeward areas not seeing any rain. Little change in the
trade wind inversion height is expected Thursday through the
weekend, greatly limiting shower activity across the entire state.
A slight increase in windward showers is possible late in the
weekend into early next week as the trades gradually return and
inversion heights begin to slowly rise.

&&

.AVIATION...
Breezy to locally strong trades will produce low cigs and SHRA on
windward and mauka zones through the period. MVFR conds possible
in any SHRA. The arrival of elevated instability favors a chance
for isolated TS over interior and upslope sections of the Big
Island this afternoon.

AIRMET Sierra is in effect for mtn obsc for windward Big Island
and N thru SE sections of the smaller islands.

AIRMET Tango for lee turb remains in effect.

&&

.MARINE...
Broad high pressure north of the state will maintain fresh to
strong trade winds today as a Small Craft Advisory (SCA) remains
in effect for all waters around the Big Island and Maui County and
select areas around Oahu and Kauai through this afternoon. The
ridge will continue to weaken as the SCA will be trimmed back to
the waters around Maui County and the Big Island through tonight.
The ridge further erodes and displaces the ridge southward over
the islands Thursday into Friday, causing the trades to diminish
significantly and possibly become disrupted. The SCA will be
dropped completely by this time. Increasing moderate trades are
expected during the weekend as the ridge lifts northward.

An active south Pacific will continue the extended run of
southerly swell almost certainly through mid June. The current
south-southwest swell gotten another pulse overnight but just
below High Surf Advisory Criteria. This swell will gradually
decline through Thursday, followed by a reinforcing south-
southwest swell late Thursday and Friday that will produce south
shore surf around seasonal average. Coming into the weekend, a
larger swell will move through the islands likely near or at the
High Surf Advisory (HSA) criteria of 10 feet. Followed by a
potentially larger swell in development looking increasingly
likely to push surf well above the advisory level late next week.

A small northwest swell has continued to fill in overnight and
looks to hold today. Another pulse from the northwest will follow
Wednesday into Thursday. The fresh to strong trade wind flow is
producing rough choppy elevated seas but the wind waves will
diminish significantly after Wednesday coinciding with the light
winds through the weekend.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 PM HST this evening for Kauai
Northwest Waters-Oahu Leeward Waters-Kaiwi Channel-Maui County
Windward Waters-Maui County Leeward Waters.

Small Craft Advisory until 6 AM HST Wednesday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Windward Waters-
Big Island Leeward Waters-Big Island Southeast Waters.

&&

$$

DISCUSSION...Jelsema
AVIATION...Walsh
MARINE...Shigesato