556
FXHW60 PHFO 170113
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
313 PM HST Fri May 16 2025

.SYNOPSIS...
Seasonably wet and breezy trades prevail into next week.

&&

.DISCUSSION...

High stability prevails in the mid-levels as a typical breezy trade
wind pattern remains established over the area. An upper low of low-
latitude origin sits over the area bringing a slight reduction in
stability as the inversion on this morning`s observed soundings was
rather soft and not as sharp as normal. As a consequence, the band
of showers advancing through the state today has had no issue
maintaining showers around 10-12kft deep even during the unfavorable
peak heating period. This is in turn enhancing leeward shower
penetration, especially over Oahu, and contributing to pockets of
heavier showers over windward/mauka portions of all islands.

The next 24-30 hours will be characterized by little overall change
except for a subtle veering of the low level flow to a more ESE
direction. Given adequate moisture availability in the boundary layer,
this has caused several members of today`s guidance suite to hint at
potential for banding within convergent ESE flow (i.e. Molokai/Lanai
plumes) both this afternoon and tomorrow afternoon. This type of
setup generally remains highly uncertain until it is underway,
though it tends to favor southern/central Oahu including the
Honolulu area urban corridor. At present, a loosely organized
plume of mostly light rain originating over leeward Molokai is
indeed streaming over southern portions of Oahu. This band of
rain will likely persist for the next few hours. Weak convergence
observed within this band suggests limited prospects for
strengthening.

Upper-level flow maintains a cyclonic character well into next week
aiding slightly lowered stability and providing a boost to trade
wind showers. As surface high pressure remains established north of
the islands, a breezy and seasonably wet trade wind pattern is
forecast to prevail for the next several days.

&&

.AVIATION...

A moderate to locally breezy trade wind pattern of mostly windward
showers and passing low clouds will continue into early next
week. Currently, scattered showers favor windward sides of the
island chain. As winds turn more southeast, plumes of moisture
will funnel additional showers across leeward areas during the
afternoon and early evening hours. MVFR or even brief IFR ceilings
and visibilities can be expected within any showers.

AIRMET Sierra remains in effect for mountain obscuration along
windward sections across the island chain. These conditions will
likely continue into the night.

AIRMET Tango remains in effect for low level moderate turbulence
over and immediately S through W of all island mountains.

&&

.MARINE...

Strong high pressure will remain anchored northeast of the state
through 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) remains 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 through 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 seasonal normals
during the next 7 days.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 AM HST Saturday for Kaiwi Channel-
Maui County Windward Waters.

Small Craft Advisory until 6 PM HST Saturday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Windward Waters-
Big Island Leeward Waters-Big Island Southeast Waters.


&&

$$


DISCUSSION...JVC
AVIATION...Farris
MARINE...TS