756
FXHW60 PHFO 051412
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
400 AM HST Fri Dec 5 2025

.SYNOPSIS...
Light to occasionally breezy easterlies will gradually drop
off through the day. Today`s highest rain chances will be over
windward Big Island and the island of Maui. A dry weekend for
many with limited clouds and infrequent showers focusing along
upslope windward mauka mainly overnight and leeward Big Island
during the day.


&&

.DISCUSSION...
The upper trough west of the islands is weakening and continuing
to move north as it encounters a large upper ridge northeast of
the region this morning. The surface pressure gradient from the
surface high centered 1,400 miles northeast of Oahu is tight
enough across the region to support moderate to locally strong
offshore easterlies. These winds will persist through the
afternoon and may become occasionally gusty across many windward
exposures and around higher terrain through most of the day. The
latest slug of moisture has advanced across Big Island and dropped
a solid quarter to a half an inch of rain along windward Mauna
Kea and Mauna Loa this morning. Shortwave IR imagery showing less
consolidation of thicker, warmer clouds east of the state. This
verifies the global deterministic guidance of a drying atmosphere.
There is one batch of higher moisture/deeper clouds southeast of
Big Island that will come across later this morning. This will
introduce return showers to windward Big Island through the early
afternoon. The upper trough and associated southern branch of the
polar jet are both losing their punch. The trough will wash out
along its northeast journey around upper to mid level ridging east
of the state and open the door for prevailing dry conditions this
weekend. This morning`s Lihue sounding provided more than a
reasonable doubt indication of drier weather (Hilo`s data is skewed
moist as the balloon ascended through showers). A near 6-7k ft
inversion will not be deep enough to support much in the way of
organized cells. The only measurable rain will fall upslope windward
or within higher elevations into the mid to late afternoon. Ridging
will build in from the west southwest and envelope the state early
next week. Subtle weakening of the surface high off the U.S West
Coast early next week will maintain gentle to breezy trades through
the middle of next week. Ridging will introduce a thick slab of
subsident, very dry air over the islands that will equate to a
shallower boundary layer; more sun with little to no mentionable
light precipitation. Confidence is moderately high of a drier
beginning of the week under seasonable trades as the majority of the
NWP model ensemble members maintain very low to no QPF over Hawaii
and its surrounding waters next week.

The weather pattern may undergo change late next week as the next
North Pacific trough moves across the central basin. The leading
front appears to behave the same way as this current one...stalling
west of Kauai as the bulk of the upper level support/energy is
directed northeastward. There may be a diffuse lower level boundary
that is pushed into the central waters sometime next Friday or
Saturday. The only way a weak front will advance into our waters is
if shortwave energy dives into the weakening trough and provides the
needed umph to progress a light wind shift eastward. Since both long
range deterministic models are way out of phase and disagree on the
evolution of this next feature, confidence is extremely low on any
significantly impactful weather by Day 7. The best signal may be a
very weak wind field if the islands fall into a pressure col,
allowing localized breezes to play a more dominant role. This
scenario would mean more leeward and further interior showers but
little rain to ease the pain of this moderate to severe drought.


&&

.AVIATION...
VFR conditions with gradually weakening easterlies will prevail
today and tonight. Cats will briefly fall into MVFR within more
moderate passing showers over Hilo or possibly Molokai or Lanai.
Possible brief mountain obscuration over the eastern half of the
state this morning.

No AIRMETs are in effect or are anticipated in the short term.


&&

.MARINE...
A trough west of Kauai will gradually weaken and retrograde
westward, away from the islands. Meanwhile, a ridge of surface
high pressure building northeast of the state will allow for
moderate to locally strong east to east southeast winds to persist
through early Saturday. A Small Craft Advisory (SCA) remains in
effect through 6 AM Saturday morning for most of the marine zones
surrounding the Big Island and Maui County and western zones
around Kauai and Oahu for winds and seas.

A moderate, medium period northwest swell (320 degrees) has filled
in across north and west facing shores bringing surf heights
above High Surf Advisory (HSA) criteria. This swell is expected to
peak this morning, then ease into the weekend. A HSA is in effect
for north and west facing shores of Kauai, Oahu and Molokai and
north shores of Maui. This swell will hold today, then gradually
fade and veer to the north northwest through the remainder of the
weekend and into early next week and bring below average surf for
December for north and west facing shores.

East shore surf will gradually build and become choppy today as
trade winds increase. Expect minimal background energy for south
facing shores through much of the week.

Peak monthly tides combined with water levels that are running
higher than predicted will likely lead to minor flooding along
the shoreline and in low-lying coastal areas. Coastal flooding is
possible around the daily peak tide, which will be during the
early morning hours. This could also magnify effects of the high
surf on coastal areas along north and west facing shores around
the same time frame.



&&

.FIRE WEATHER...
Critical fire weather conditions are not expected this week.
Light to occasionally moderate trades today, but winds will remain
below the critical fire weather threshold. The lack of any
significant rain will exacerbate already dry conditions across the
entire state. The inversion morning sloped from around 6,500 ft
at Lihue to around 9,000 ft over Hilo.



&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory until 6 PM HST this evening for Niihau-Kauai
Leeward-Waianae Coast-Oahu North Shore-Maui Windward West-Kauai
North-Molokai Windward-Molokai North-Molokai West-Maui Central
Valley North-Windward Haleakala.

Small Craft Advisory until 6 AM HST Saturday for Kauai Northwest
Waters-Kauai Windward Waters-Kauai Channel-Oahu Windward Waters-
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...Blood
AVIATION...Blood
MARINE...Walsh
FIRE WEATHER...Blood