912
FXHW60 PHFO 010206 CCA
AFDHFO

Area Forecast Discussion...CORRECTED
National Weather Service Honolulu HI
406 PM HST Thu Jul 31 2025

.SYNOPSIS...
Breezy to locally windy trades and rather dry and stable
conditions will persist through Friday and likely Saturday.
Clouds and light showers will be focused over windward and mauka
areas, while most leeward areas remain dry. Stable trade winds
will gradually ease Sunday through Tuesday.

&&

.DISCUSSION...
A gusty, stable, and rather dry trade wind flow is in place. Even
though the surface high far north of Hawaii is not exceptionally
strong, activity in the tropics south of Hawaii is producing a
somewhat tight pressure gradient over the region. In addition, a
ridge aloft overhead is producing an inversion based between
roughly 5,000 to 6,000 feet. Under these very stable conditions,
trades are being accelerated over and downwind of terrain, and
winds are strong enough to require a Wind Advisory over portions
of Maui County and the Big Island. Shallow pockets of moisture
moving along the trade wind flow have led to only light rainfall
accumulation along windward slopes and dry weather leeward.

Little change is expected on Friday and likely Saturday. The
surface high north of the state will strengthen slightly as it
drifts eastward, and a surface trough in the deep tropics will
pass south of the islands, keeping the pressure gradient rather
tight. The Wind Advisory runs through Friday afternoon, and
depending on how quickly the surface trough to the south moves
westward, winds may hold around current strength through
Saturday. Modest showers will remain confined to windward areas.

Trade winds will gradually decline Sunday into Tuesday as the high
drifts eastward and the local pressure gradient slowly relaxes.
The stable pattern of mainly windward and mauka showers should
persist as little organized moisture is depicted in the guidance.

Some uncertainty is introduced by the middle of next week. The
latest National Hurricane Center forecast depicts current east
Pacific Tropical Storm Gil weakening to a remnant low well east of
Hawaii early next week, and the GFS and ECMWF show a remnant
circulation passing near the state around Wednesday or so. It`s
too early to determine what, if any effects, this feature will
bring for island weather.

&&

.AVIATION...
Breezy to windy trade winds will persist through tomorrow and
allow for prevailing VFR conditions. MVFR conditions may occur
with passing showers over windward and mountain areas, especially
overnight and in the early morning hours.

AIRMET Tango is in effect for moderate with isolated severe
turbulence over and immediately S through W of the island
mountains due to breezy trade winds and recent reports of severe
turbulence.

&&

.MARINE...
High pressure far northeast of the state will help generate fresh
to locally near gale trades through the weekend. A Small Craft
Advisory (SCA) is in effect for most marine zones surrounding Maui
and the Big Island and has been extended through Friday night.
Additional zones may need to be added to the SCA this weekend due
to increasing winds as the high pressure to the north strengthens.
Trades then begin to weaken early next week as the aforementioned
high drifts further east.

Tropical Storm Iona continues to track to the west, far west-
southwest of the main Hawaiian Islands. Additional tropical
cyclone development is possible far south-southeast of Hawaii
over the next day or so, but expecting little to no impact on our
local waters.

A long period south swell continues to filter into our local
waters this afternoon and is expected to peak late today through
tomorrow, then slowly decline thereafter. A High Surf Advisory
remains in effect for the south facing shores of all islands
through tomorrow afternoon. This first south swell event will be
followed by another long period south swell early next week.

East shore surf will remain elevated and choppy due to locally
strong trade winds through this weekend. This will be followed by
a decline early next week as trades weaken.

Flat summer conditions along north facing shores may be
interrupted late this weekend by a small long period northwest
swell from Tropical Storm Krosa, currently in the western
Pacific.

&&

.FIRE WEATHER...
A gusty, stable, and rather dry trade wind flow will remain in
place through Friday and likely into Saturday. Critical fire
weather conditions, with winds of 20 mph or more and daytime
relative humidity of 35 to 45 percent, is expected to persist
over leeward areas through Friday afternoon, and possibly into
Saturday. A strong inversion based around 5,000 feet will ensure
that higher elevations of the Big Island and Haleakala on Maui
experience very low relative humidity. Winds will decline Sunday
into Tuesday, lowering fire weather concerns.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 6 PM HST Friday for Niihau-Kauai South-
Kauai Southwest-East Honolulu-Honolulu Metro-Ewa Plain-Waianae
Coast-Oahu North Shore-Central Oahu-Waianae Mountains-Molokai
North-Molokai West-Molokai Leeward South-Lanai Windward-Lanai
Leeward-Lanai South-Lanai Mauka-Kahoolawe-Maui Leeward West-Maui
Central Valley North-Maui Central Valley South-South
Maui/Upcountry-South Haleakala-Big Island South-Big Island
Southeast-Kohala-Big Island Interior.

High Surf Advisory until 6 PM HST Friday for Niihau-Kauai
Leeward-Waianae Coast-Kahoolawe-Maui Leeward West-Kona-Kauai
South-East Honolulu-Honolulu Metro-Ewa Plain-Molokai Southeast-
Molokai Leeward South-Lanai Leeward-Lanai South-Maui Central
Valley South-Kipahulu-South Maui/Upcountry-South Haleakala-Big
Island South-Big Island Southeast.

Wind Advisory until 6 PM HST Friday for Lanai Mauka-Kahoolawe-
Kohala-Lanai Windward-Lanai Leeward-Maui Central Valley North-
Maui Central Valley South-Big Island South-Big Island Southeast-
Big Island North.

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

&&

$$

DISCUSSION...Wroe
AVIATION...Tsamous/Trotter
MARINE...Farris/TS
FIRE WEATHER...Wroe