075
FXHW60 PHFO 210125
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
325 PM HST Sat Jul 20 2024

.SYNOPSIS...
Trade winds will continue through much of the upcoming week.
Moderate trades this weekend will become breezy to locally windy
early in the new week. A disturbance is expected to move through
Tuesday which will bring an uptick in shower activity,
particularly to windward and mountain areas.


&&

.DISCUSSION...
Some tweaks to the winds in the short term have been made for the
afternoon package, along with some refinements in other grids
through the forecast period. No significant changes since the
morning update.

The surface trough that was moving over the islands this morning
has largely dissipated over the islands, with a portion of the
trough remaining south of the islands. The clouds and showers that
were impacting the southern end of the state have thinned, and
with that, a return to more typical trade wind shower pattern has
returned, with clouds and some showers focused over the windward
sides of the islands. Modest rainfall totals are expected through
Monday.

A trough to the north of the islands has been disrupting the trade
wind flow, keeping trades at moderate levels. This trough is
expected to move to the west which will allow for an uptick in
trade winds over the next couple of days. Another boost to the
trades is expected midweek behind another surface trough. Winds
during the middle to latter part of the week which become locally
strong in some areas.

The trough about 1200 miles east of the islands will continue to
move to the west and weaken. However despite weakening, there is
good model agreement that this system will bring another uptick in
showers to the region Tuesday. While this doesn`t look to be a
widespread significant rain producer, it has the potential to
bring some brief, locally heavier rainfall to parts of the
windward sides of the islands as it moves through.

As mentioned above, behind the trough, the tight pressure gradient
will help to boost trade winds with some locations possibly
reaching low end Wind Advisory criteria. Otherwise look for a
return to more typical trade wind showers that will be focused
over the windward and mountain sides of the islands. However as
the winds pick up, some of the showers could reach leeward areas.


&&

.AVIATION...

Moderate trades will continue through the rest of the weekend
with clouds and showers favoring windward and mauka areas,
particularly overnight. In addition, clouds and showers will
build up on the Kona slopes of the Big Island each afternoon.
Brief periods of MVFR will be possible with this activity.
Otherwise, VFR should prevail.

No AIRMETs are currently in effect.


&&

.MARINE...
A strengthening high pressure system far north of the Hawaiian
Islands will increase the trade winds into the fresh to locally
strong range tonight. Trade wind speeds will be strong enough to
support Small Craft Advisory (SCA) conditions over the windier
waters and channels near Maui and the Big Island through much of
next week. An SCA has been issued for these waters through Sunday
night. Additional waters will likely be added next week as trades
increase further Monday into Tuesday.

Background south swell energy pulses are forecast to continue,
with surf remaining below average through much of next week.
Small, choppy surf is expected for east facing shores for the
next several days due to the trade winds. Surf then becomes
increasingly rough along east facing shores as locally strong
trades increase early next week.

Spring tides will peak this weekend, with local tide gauges
indicate water levels are still running about a half a foot above
guidance and at least 1 foot higher than the Mean Higher High
Water (MHHW) threshold at Hilo, Kahului, and Honolulu. The Coastal
Flood Statement for isolated minor flooding remains in effect
through Monday evening.


&&

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


&&

$$


DISCUSSION...M Ballard
AVIATION...Farris
MARINE...TS