916
FXHW60 PHFO 310150
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
350 PM HST Thu May 30 2024

.SYNOPSIS...
Surface high pressure far northeast of the islands will remain the
impetus to breezy and locally windy trade winds the next few days.
Drier weather will prevail through Friday evening. Isolated
showers will favor windward areas and become more prevalent at
night. Upper troughing to the northeast of the state will move
over the area from Friday through the weekend. This will create a
more unstable scenario and, with increasing moisture from early
next week through mid week, trade shower coverage and intensity
will likely be on the rise.


&&

.DISCUSSION...
A 1031 mb surface high is centered approximately 1,400 miles
northeast of Oahu in tandem with surface troughing located about
900 miles from Kauai. This is producing a tight enough pressure
gradient back across the island chain to maintain recent breezy
to locally windy trade winds. A drier air mass is advecting in
from the east as evidenced by today`s local sounding profiles. A
dry 850-700 mb layer, along with a stout near 5k ft inversion,
signals just isolated shower activity through the day tomorrow
(Friday). Precipitation that does develop within this relatively
shallow boundary layer will be isolated in coverage and produce
measurable accumulations of no more than a few tenths of an inch
along windward exposures. Late week cloud conditions the next
couple of days will be partly cloudy early in day becoming
progressively cloudier through the weekend. Lower elevations
will warm into the lower 80s (mid 60s to lower 70s at 6k ft
elevation) with morning readings ranging in the lower to mid 70s /
40s above 8k ft elevation in both Maui and Hawaii Counties will
be the general rule.

High pressure northeast of the state will settle more south-
southeast as the trough of low pressure west of the region slowly
lifts northward and washes out Friday. This will anchor a tight
pressure gradient across the area this weekend to maintain or
slightly boost breezy to locally windy (in gust at elevation)
trades. Heights will lower over the state from Friday into the
weekend. Extended NWP guidance is still a little out of phase with
the location of the lowest heights. The emergence of the subtropical
jet over or just south of the islands this weekend may offer more
argument to a wetter early June pattern, all dependent upon its
positioning. Mid levels of the atmosphere will remain fairly dry
until Tuesday so this may weigh the forecast toward more dry.
Regardless of any these minor model nuances, there is moderate
confidence that next week`s upper troughing scenario will increase
areal shower coverage and intensity...especially going into the
middle of next week due to higher lower to mid layer moisture.


&&

.AVIATION...
Trades have strengthened throughout the day today and we should
continue to see breezy to locally strong trade winds across the
state over the next several days. Scattered showers currently over
the Big Island and windward Maui will spread towards Oahu and
Kauai tonight. Clouds and showers will favor windward slopes with
brief MVFR conditions possible with the showers. VFR conditions
will generally prevail across leeward areas.

VAD wind profiles and soundings show winds of 20 to 30 kt below a
strong inversion between 4500 and 6500 feet. Due to the strong
winds below the inversion, AIRMET TANGO was issued for moderate
low level turbulence south through west of terrain. Currently, no
other AIRMETS are in effect, but AIRMET SIERRA for mountain
obscuration will be possible later this afternoon or tonight due
to scattered showers riding in with the strong trades.


&&

.MARINE...
High pressure centered far northeast of the area will maintain
moderate to locally strong east- northeast trade winds into
Friday. Winds will strengthen slightly to fresh to locally strong
late Friday through the weekend as the high drifts south,
tightening the gradient. A Small Craft Advisory (SCA) remain for
the typically windy waters around Maui and the Big island through
Friday afternoon. The SCA will likely need to be extended and
expanded to include additional zones around Oahu and Kauai waters
into early next week due to the strengthening trades.

Surf along exposed south-facing shores will remain small into
Friday. A series of south swells will bring a prolonged period of
above average surf along south facing shores through the start of
June. Forerunners of the first south swell are expected to arrive
Friday maintaining small surf through most of the day while
gradually building. The swell is expected to peak late Saturday
into Sunday in the 3 to 4 foot range. A reinforcing pulse should
arrive on Monday and will likely maintain surf heights near or
just below the High Surf Advisory threshold of 10 feet. Surf
heights should gradually trend down Tuesday through Wednesday as
the south- southwest (200 degree) swell declines. A gale low just
east of New Zealand, will likely bring another south (190 degree)
swell Thursday into Friday of next week.

Surf along exposed east-facing shores will continue to remain
rough and choppy due to the windswell generated by the breezy
trade winds and will likely increase slightly by this weekend.

Surf along north-facing shores will continue to remain nearly flat
over the next few days. A storm force low near Kamchatka should
produce an out of season northwest swell that is expected to fill
in late Sunday night into Monday. Latest guidance is showing 3 to
4 feet of swell from 320 degrees Monday into Tuesday. A small tropical
storm tracking off the coast of Japan will transition into a broad
extra tropical gale as it tracks north then eastward over the next
couple of days. This system could bring a small reinforcing west-
northwest to northwest swell Tuesday into the middle of next
week.


&&

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


&&

$$


DISCUSSION...Blood
AVIATION...Kino
MARINE...Almanza