386
FXHW60 PHFO 231912
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
912 AM HST Sun Aug 23 2026

.SYNOPSIS...
Locally strong and gusty trade winds will prevail today as
Tropical Storm Moke moves westward, several hundred miles south of
the islands. Moisture along the northern periphery of Moke will
bring wet conditions and a risk of flash flooding on the Big
Island through Monday, while less rainfall is expected to impact
windward sections from Maui to Kauai over the next couple of
days. Trade winds will gradually ease Monday and Tuesday as Moke
moves westward away from the area, with drier trade wind weather
returning midweek.

&&

.SHORT TERM UPDATE...
The forecast remains on track this morning as the center of
Tropical Storm Moke is passing several hundred miles south of
Hilo. While the heaviest rainfall associated with Moke is
confined just south of the coastal waters at this time, showers
are increasing on windward Big Island. Rates so far have been
relatively light, around one quarter of an inch or less per hour
across the Puna and Hilo Districts. Due to the prevailing wind
direction, little rainfall has reached the Kau District so far,
but as winds in the lower atmosphere veer more easterly to
southeasterly this afternoon and tonight, chances for heavy rain
and flooding will increase in that area.

&&

.PREV DISCUSSION...
Issued at 359 AM HST Sun Aug 23 2026
Latest IR satellite loop shows deep convection from Tropical
Storm Moke flaring up roughly 200 miles south southeast of Hilo.
Low level clouds and moisture on the northern periphery of the
cyclone can also be seen racing westward towards Big Island at a
steady clip. Radar is picking on these bands and depicts
scattered light to embedded moderate shower activity. Radar
estimated rain rates remain unimpressive though, mainly below a
tenth of an inch an hour. By early afternoon, the high resolution
WRF-ARW, WRF-FV3, and namNest model guidance all indicate a rather
stark increase in rainfall coverage and intensity along eastern
portions of Big Island. It will not take a significant amount of
rain to cause flash flooding due to saturated grounds from recent
heavy rain from TC Lala. Thus, a Flood Watch will remain in effect
for Big Island through Monday afternoon. Rainfall amounts for the
event appear in good order, as NHC`s track for Tropical Storm
Moke barely budged from the previous advisory package. Storm
total forecast for windward and southeast Big Island remains at 5
to 10 inches with locally up to 15 inches, 3 to 6 inches for
eastern Maui, and generally 1 to 2 inches elsewhere across the
island chain.

Locally strong trade winds persisted overnight as Hawaii remained
sandwiched between low pressure of Tropical Storm Moke south of
the state and a 1025 mb surface high to the northeast. A Wind
Advisory remains in effect through this evening for portions of
Maui, Molokai, Lanai, Kahoolawe, and Big Island. Strongest
sustained winds will continue to occur over mountain ridges, gaps
and where winds blow downslope off higher terrain. Observed speeds
in these areas have generally been sustained 25 to 35 mph with
gusts up to 55 mph. Winds across the ridge tops of the Ko`olau and
Waianae mountain ranges may near advisory criteria later today as
trade wind showers and/or deeper moisture bands from the
northern periphery of Moke begin to arrive. Those zones will be
left out of the advisory for now, but may have to be included if
the stronger winds expand further west. Trade winds across all
islands should begin to ease back to moderate by tonight.

Tuesday through the end of next week, drier air will move in from
the east, and typical trade winds/showers should return.

&&

.AVIATION...
Tropical Storm Moke was centered roughly 300 hundred miles south
of the Big Island and continued on its west-northwestward track.
Rain bands from the tropical storm will impact windward Big Island
today, which will bring MVFR and periods of IFR conditions to the
area.

Trade winds are expected to be moderate to locally strong
statewide. Outside of windward Big Island, showers embedded
within the trade wind flow will primarily impact windward and
mountain areas, bringing periods of MVFR conditions. Otherwise,
VFR will prevail.

AIRMET Tango is in effect for low level turbulence downwind of
terrain due to the strengthened trade winds. AIRMET Sierra is in
effect for mountain obscurations over windward Big Island and
Kauai and may be expanded to other islands today. An AIRMET for
IFR conditions over portions of windward Big Island is also a
possibility later today.

TC SIGMET series XRAY covers Tropical Storm Moke and its
convection.

&&

.MARINE...
Northeast winds have strengthened across the Hawaiian Island
coastal waters, mainly around windward Big Island, as a result of
Tropical Storm (TS) Moke passing west across the far southern
offshore waters. At 5 AM HST, the center of Moke was located 270
nautical miles south Hilo. A Tropical Storm Warning is in effect
for the offshore waters. Intense convection associated with this
storm is flaring up north of its center and will impact the
southeastern offshore waters generally south of 18N today. An all-
water Small Craft Advisory (SCA) is in effect to account for
fresh to locally strong trades between surface high pressure
located far northeast of the islands and TS Moke. Higher winds and
short period wind wave swell generated by TS Moke may push
significant sea heights to 10 feet or slightly higher across Big
Island windward waters today.

East-facing shore surf will build today in response to
strengthening trades. Surf along east and south-facing shores
will be impacted by a short period east southeast swell generated
by TS Moke as well as northeast wind wave swell as a result of
these stronger trades. As Moke passes by to the south today and
Monday a mounting southeast swell will veer and become south to
southwest. This small, short period captured easterly fetch from
TS Moke may push Big Island east surf to near advisory levels
later today.

Surf along most south-facing shores will be slightly below summer
norms but still remain somewhat elevated due to a lingering small,
long period south southwest swell. A three to four foot, medium to
long period south swell is expected to arrive Monday and Tuesday
which will maintain these near summertime heights.

Small, medium to long period west to north swell originating from
Hurricane Lala is passing around north and west-facing coasts
today.

&&

.FIRE WEATHER...
Trade winds will be locally strong and gusty today. The inversion
will steadily weaken and erode as moisture associated with TS
Moke moves into the area today. Heavy rain is expected over
windward and SE facing slopes of Big Island through Monday, while
rainfall will largely be focused over windward slopes elsewhere.
over wind-exposed leeward areas, humidity will be slightly
elevated, leading to moderate fire weather concerns today. Winds
will gradually ease Monday. A typical summertime trade wind
pattern will return by Tuesday.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 6 PM HST this evening for Big Island
Interior-Big Island North-Big Island South-Big Island Southeast-
Kahoolawe-Kohala-Lanai Leeward-Lanai Mauka-Lanai Windward-Maui
Central Valley North-Maui Central Valley South-Maui Leeward West-
Molokai Leeward South-Molokai North-Molokai Southeast-Molokai
West-South Haleakala-Windward Haleakala.

Flood Watch through Monday afternoon for Big Island East-Big
Island Interior-Big Island North-Big Island South-Big Island
Southeast-Big Island Summits-Kohala-Kona.

Small Craft Advisory until 6 PM HST this evening for Alenuihaha
Channel-Big Island Leeward Waters-Big Island Southeast Waters-
Big Island Windward Waters-Kaiwi Channel-Kauai Channel-Kauai
Leeward Waters-Kauai Northwest Waters-Kauai Windward Waters-
Maalaea Bay-Maui County Leeward Waters-Maui County Windward
Waters-Oahu Leeward Waters-Oahu Windward Waters-Pailolo Channel.

&&

$$

UPDATE...Wroe
DISCUSSION...Thomas
AVIATION...Munroe
MARINE...Blood/Wroe
FIRE WEATHER...Thomas/Wroe