763
FXHW60 PHFO 240705
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
905 PM HST Sun Jun 23 2024

.SYNOPSIS...
High pressure north of the state will maintain breezy trade winds
the next couple of days. Showers will favor windward coasts and
slopes. Trades will slightly weaken around the middle of the week
with an increase in shower activity late in the week.


&&

.DISCUSSION...
The downstream pressure gradient from a 1030 mb high centered
approximately 950 miles north northwest of Kauai remains tight
enough across the region to maintain breezy to locally windy
trade winds through Tuesday. A Wind Advisory is in effect for Big
Island summits. Easterlies at the summits will reach 45 mph and
gust to around 55 mph through the overnight hours. Expect these
winds to begin trending down through the daylight Monday morning
hours. The state will remain under the stabilizing influence of
mid-level ridging as the islands reside along the southeasterly
periphery of a 700 mb ridge positioned to the northwest. Evening
radar and satellite imagery show relatively drier conditions
compared to last night with widely scattered weak trade showers
traveling across the isles. Expect these conditions to continue
overnight with showers favoring windward exposures.

Higher mid-level moisture advecting in and deepening a more moist
boundary layer the next few days, along with the emergence of the
jet draped across the southern half of the state, should be the
impetus to increased shower coverage that will produce a few
hundredths of an inch more rain within those communities that
typically stay wet during a normal summertime trade pattern.
Aside from some brief afternoon showers over the Kona slopes of
Big Island, leeward areas will remain mostly dry. Little to no
movement of the lower and upper ridge planted north of the islands
through Tuesday ensures breezy trades under partly to mostly
cloudy windward skies/mostly to partly sunny leeward skies.

High pressure at all levels begins to transition east during the
latter half of the week. This will weaken the lower level pressure
gradient enough to subtly suppress trade flow to more gentle
magnitudes through the middle of the week, although easterlies
will still remain breezy along ridge lines and within those
valleys parallel to trade flow. Lowering mid to upper heights,
with periodic ribbons of higher moisture passing to the west, will
increase shower frequency and areal coverage later in the week.
The development of a mid to late week upper level trough/cut-off
low east northeast of the islands will move north of the area
this weekend. This scenario will certainly boost weekend rain
chances as the low moves north of the state the last few days of
June.


&&

.AVIATION...
Breezy to locally windy trades will continue through Monday.
Showery cloud bands embedded in the trade flow will produce
periods of MVFR conditions across windward/mauka areas of each
island, particularly through the overnight and early morning
hours. Conditions will improve through the late morning and
afternoon periods.

AIRMET Sierra remains in effect for tempo mountain obscuration
for windward slopes of most islands, which will likely continue
through Monday morning.

AIRMET Tango remains in effect for mod low-level turb over and
downwind of island terrain due to the breezy trade winds. This
AIRMET will continue through Monday.


&&

.MARINE...
Surface high pressure centered roughly 900 nm north of the state
will remain stagnant through early this week and help to drive
fresh to strong easterly trades. The Small Craft Advisory (SCA)
remains in effect through Monday night for all local waters south
and east of Maui County. Trades weaken slightly Tuesday into mid-
week as the high moves east northeastward, away from the islands.

Surf along east-facing shores will remain rough and choppy through
Monday followed by a gradual downward trend during mid-week as
trades weaken slightly.

Expect slightly elevated surf, near or slightly below seasonal
norms, along south facing shores through Tuesday as a small,
medium period, south swell moves through. However, this should be
short-lived, with a downward trend expected by Tuesday night. More
small, medium to long period, south swells will return Wednesday
night through the weekend.

Nearly flat conditions along north facing shores expected through
mid day Monday. A small, medium period, northwest swell will
bring tiny surf to north facing shores late Monday through mid-
week.


&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 6 PM HST Monday for Big Island Summits.

Small Craft Advisory until 6 PM HST Monday for Maui County
Leeward Waters-Maalaea Bay-Pailolo Channel-Alenuihaha Channel-
Big Island Windward Waters-Big Island Leeward Waters-Big Island
Southeast Waters.


&&

$$


DISCUSSION...Blood
AVIATION...Gibbs
MARINE...Thomas