821
FXHW60 PHFO 241435 CCA
AFDHFO

Area Forecast Discussion...CORRECTED
National Weather Service Honolulu HI
435 AM HST Mon Jun 24 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 a possible increase in weekend shower activity.


&&

.DISCUSSION...
The downstream pressure gradient from a 1031 mb high centered
approximately 860 miles north northwest of Kauai remains tight
enough across the region to maintain breezy to locally windy trade
winds through Tuesday. 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 northwest of
the area. Early morning radar and satellite imagery show fairly
dry conditions with only widely scattered weak trade showers
traveling across the isles. Expect these conditions to continue
through the day with showers favoring windward exposures.

Higher 850-700 mb layer moisture advection assisting in deepening
a more moist boundary layer Tuesday and Wednesday, in tandem with
the emergence of a subtropical jet draped across the southern
nearshore waters, should be the impetuses to increased shower
coverage. Those communities that typically stay more wet than dry
during normal summertime trades will likely pick up a few
hundredths to tenths of an inch more rain through mid week.
Aside from a few brief afternoon showers over the Kona slopes of
Big Island or a stray windward cell making it over the ridgeline,
leeward areas will primarily remain dry. Little to no movement of
lower and upper ridging anchored 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
second half of the week. This will weaken the lower level
pressure gradient enough to subtly suppress trade flow to more
gentler magnitudes, although easterlies will still remain breezy
along ridge lines and within valleys parallel to trade flow.
Lowering mid to upper heights, with periodic ribbons of higher
east moisture passing to the west, will increase late week shower
frequency and areal coverage. An upper trough/cut-off low develops
east of the islands from the middle of the week onward. This
scenario may boost weekend into early week rain probabilities
across more windward waters/exposures. The highest rainfall will
likely be focused north of the island chain as the low moves north
northwest of the state early next week.


&&

.AVIATION...
Breezy to locally windy trades will continue today, then gradually
ease late tonight through Tuesday. 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 the morning hours.

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 the day.


&&

.MARINE...
Surface high pressure centered roughly 950 nm north of the state
will help to drive fresh to strong easterly trades today. The
Small Craft Advisory has been extended until Tuesday morning, but
trimmed back to only include the typical windier waters around
Maui County and the Big Island. 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 today
followed by a gradual downward trend during mid week as trades
weaken slightly.

Surf along south-facing shores will be near or slightly below
seasonal norms through Tuesday as a small, medium period, south
swell continues to move through. Nearshore buoys showed swell
energy peaking this morning in the 12-14 second range. 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 remainder of the forecast
period.

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


&&

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


&&

$$


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