988
FXHW60 PHFO 182000
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
1000 AM HST Wed Sep 18 2024

.SYNOPSIS...
Gentle to breezy trade winds will prevail the next several days.
A drier statewide weather pattern will occur through the remainder
of the week. Occasional showers will mainly focus along higher
windward terrain with more frequent overnight shower activity.
Areal rainfall may pick up early next week as an upper low north
of the state comes in close proximity of the islands.


&&

.DISCUSSION...
A 1030 mb high centered approximately 1,000 miles north of Hawaii
is producing a tight enough pressure gradient back toward the
state to maintain statewide gentle to breezy trade winds. Little
movement nor weakening of this high the next couple of days
guarantees similar trade behavior through Thursday. While the
high will subtly weaken and shift east from Friday into the
weekend, overall winds will remain at gentle to breezy magnitudes
into early next week. Thus, diurnal precipitation behavior will be
of a trade nature...mainly windward and upper terrain shower
activity with more frequent overnight showers. The same climate
caveats will also apply such as increased afternoon cloud cover
and rain over Big Island Kona and occasional morning leeward side
sprinkles. A drier mid-level air mass advecting across the islands
the next few days has the forecast trending on the drier side of
traditional trade flow climate.

There is potential change to the regional weather pattern this
weekend as a couple of upper lows (or weak troughs) northwest and
northeast of the state consolidate and descend south toward the
area. While numerical guidance is out of phase with this regional
lowering of heights, a signal has been noted and this will likely
equate to a transition to a more wet pattern by early next week.
As upper heights begin to fall this weekend, mid to upper levels
will cool and moisten. The question will be how the synoptic
shapes up concerning the `when` and `how long` of increased
statewide precipitation. Hence, the current forecast will lean
toward a more wet forecast next Sunday through the middle of the
week in relation to these lowering heights from a potential upper
low forming over or near the islands.


&&

.AVIATION...
Moderate to breezy trade wind flow will prevail for the next
couple of days. Stable conditions will result in only limited
areas of low ceilings and temporary MVFR conditions over windward
and mountain locations. Aside from afternoon clouds over Kona
slopes of the Big Island, VFR conditions should prevail for most
locations.

AIRMET Tango remains in effect for low-level turbulence over and
downwind of island terrain. This AIRMET will likely remain in
effect at least for the next couple of days.


&&

.MARINE...
High pressure north northeast of the Islands will keep moderate
to locally strong trade winds in place through the weekend. A
slight weakening of the high could decrease wind speeds early next
week. A Small Craft Advisory (SCA) is now in effect for the
typically windy waters around Maui and the Big Island through 6 AM
Friday. The SCA may eventually need to be extended through the
weekend.

East shore surf will hold near seasonal levels through Thursday,
then slowly lower Friday through early next week. A mix of
southeast, south and southwest swells will keep small surf
in place for south facing shores through Monday. A slight bump in
south shore surf is possible around Tuesday or Wednesday of next
week as a slightly larger long-period southwest swell arrives.
North shore surf will remain very small through the weekend until
Tuesday and Wednesday of next week when a 3 to 5 foot medium to
long- period northwest swell could arrive.


&&

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


&&

$$


DISCUSSION...Blood
AVIATION...Vaughan
MARINE...Birchard/Tsamous