High Surf in Hawaii, June 28 to 29, 2020

Area Forecast Discussion
National Weather Service Honolulu HI
302 AM HST Sun Jun 28 2020

.SYNOPSIS...
A surface high will remain far northeast of the area through
Independence Day and keep northeast to east trade winds blowing
over the islands. A trough passing north of the area will keep the
trades light to moderate through Monday. Winds will become
locally breezy again by midweek. The trades will focus scattered
showers over windward areas, especially during the night and early
morning hours. Sea breezes will produce afternoon showers over
leeward areas of the Big Island and Maui. The lighter trade winds
today and Monday will allow sea breezes to produce afternoon
clouds and showers on the smaller islands as well.

&&

.DISCUSSION...
The 2 AM surface analysis shows a 1033 mb surface high far
northeast of the main Hawaiian Islands near 43N 151W. This high
will remain far northeast of the islands through the week and
maintain northeast to east trade winds over the islands. Satellite
loops show scattered to broken low clouds moving toward the
islands in the trade-wind flow. These clouds will produce
scattered showers over windward areas through the week. These
windward showers will be most active during the night and early
morning hours. Sea breezes will produce clouds and showers over
lee slopes of the Big Island and Maui daily.

A surface trough passing north of the state will weaken the trade
winds through tomorrow. With the lighter trade winds, sea breezes
will become more widespread today and could produce afternoon
clouds and showers over leeward and interior area of the smaller
islands. Later in the week, the trade winds will be strong enough
to prevent widespread sea breezes on the smaller islands. The high
mountains on the Big Island and Maui block the trade winds from
reaching leeward areas so sea breezes will continue to produce
afternoon clouds and showers over leeward areas on those islands.

&&

.AVIATION...
VFR conditions are expected to prevail through tonight. A weak
trough to the northeast of the islands is helping to disrupt the
trade wind flow, with lighter trades expected today. A few
showers are possible over the windward and mountain areas within
the trade wind flow. The winds could weaken enough in some areas
for localized land and sea breezes, which could lead to some
clouds and showers developing over leeward or interior sections
during the afternoon hours.

No AIRMETs currently in effect and not anticipating the need for
any today.

&&

.MARINE...
Light to moderate trade winds will continue through Monday as a
weak surface trough passes to the north. Surf along east facing
shores will lower as the winds weaken. Breezy trade winds will
return Tuesday, increasing surf along east facing shores. A
building south swell today will bring advisory level surf to south
facing shores through Monday, and then decline Tuesday. A smaller
south swell is forecast to arrive Wednesday, maintaining surf
near the seasonal average Wednesday and Thursday. Some areas
exposed to the south swell along west and east facing shores will
also see an increase in surf.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory till 6 PM Monday for south facing shores of all
Hawaiian islands.

&&

DISCUSSION...Donaldson
AVIATION...M Ballard
MARINE...Morrison