722
FXHW60 PHFO 161315
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
315 AM HST Fri May 16 2025

.SYNOPSIS...
A high pressure ridge will remain locked in place north of the
Hawaiian Islands through much of next week. Expect continued
moderate to locally breezy easterly trade winds with brief periods
of showers mainly over windward and mountain areas, favoring the
overnight to early morning hours. A weak upper level low over the
islands will produce periods of enhanced shower activity into the
weekend. The Kona slopes of the Big Island may also see scattered
to numerous afternoon showers.

&&

.DISCUSSION...
The satellite picture this morning shows a narrow upper level
trough extending from west to east across the Central Pacific
basin. A weak upper low remains anchored directly over Hawaii,
bringing a flavor of instability to the cloud bands riding into
each island on the trade winds that will last through Sunday.
Farther to the north, the subtropical ridge remains anchored in
place for the next seven days, keeping moderate to locally breezy
trade winds in the forecast through much of next week. A band of
unstable clouds is currently moving into the islands from the
east, producing wet roads this morning for some island commuters.

The island weather pattern will remain in a fairly unsettled
trade wind regime into the first half of next week, mainly due to
the proximity of the upper level low pressure system keeping
temperature inversion heights in the 8,000 to 10,000 foot range.
At this level cloud heights grow tall enough as they are lifted
over island mountains to produce periods of rainfall, especially
during the diurnal rainfall maximum from the overnight to early
morning hours. A brief period of thunderstorms are possible on
Saturday afternoon along the western slopes of the Big Island, as
deeper moisture at 700 mb is lifted by strong surface heating
along the slopes of Mauna Loa.

Our forecast guidance into next week shows a very similar weather
pattern with the ridge locked in north of the state and a weak
upper low lurking over the Hawaiian Islands. Only subtle changes
in the island by island weather pattern should be expected over
the next seven days.

&&

.AVIATION...
Moderate to breezy trade winds continue across the island chain
into Saturday, steered by high pressure centered far northeast of
the main Hawaiian Islands. Low clouds and passing showers embedded
within the trades will favor north through east sections of most
islands throughout the period, especially during the overnight to
early morning hours. While VFR flight conditions will prevail at
most locations, periods of MVFR conditions will be possible within
any showers especially over windward airfields.

AIRMET SIERRA remains in effect for mountain obscurations along
windward sections of Oahu, Molokai, Maui and the Big Island. These
conditions will continue through the morning hours.

AIRMET Tango remains in effect for low level moderate turbulence
over and immediately S through W of all islands mountains. AIRMET
Tango also remains in effect for upper level moderate turbulence
from Molokai eastward to the Big Island. Low level turbulence
impacts will continue into the weekend.

&&

.MARINE...
Strong high pressure will remain anchored northeast of the state
today and tonight, keeping fresh to strong trades in place. A
developing trough to the distant northwest is expected to ease the
trades over the weekend into early next week. Light to moderate
trades with localized sea breezes are expected over the western
islands, while moderate to locally strong persist over the eastern
end of the state.

A Small Craft Advisory (SCA) is now in effect for most marine
zones east of Oahu through 6 am Saturday, and for some of the
windier zones around Maui and the Big Island through 6 pm
Saturday. The SCA may need to be extended for the typically windy
waters over the eastern end of the state through the weekend.

Surf along north and west-facing shores will remain very small
during the next 7 days. Surf along south-facing shores will hold
at background levels today and tonight. A series of small south
and south-southwest swells will give a small boost to south shore
surf over the weekend, with a further boost up to the seasonal
average possible during the middle to latter part of next week.

Surf along east-facing shores will hold close to normal levels
during the next 7 days.

&&

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

&&

$$

DISCUSSION...Bohlin
AVIATION...Bohlin/Almanza
MARINE...Jelsema