663
FXHW60 PHFO 071346
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
346 AM HST Sun Dec 7 2025

.SYNOPSIS...
Light to moderate trades with embedded showers favoring
predominately windward and mauka areas are expected through the
day, followed by drier and more stable conditions through the
first half of the week. Winds will begin ease by Wednesday and
veer southerly in response to an advancing front northwest of the
islands. This front is expected to move over the islands during
the latter half of the week, potentially increasing shower
activity.


&&

.DISCUSSION...
Latest radar data indicate the volcanic ash from Kilauea`s
Halemaumau Crater during episode 38 that started decreasing
yesterday evening, has further decreased this morning. Radar
observations as of 13z (3am HST LT) show the plume now at
approximately 10000 feet mean sea level (MSL), with light ashfall
possible southwestward within 5 miles from the volcano source.

Moderate trades continue to ease as an upper-level trough
propagates into the vicinity of the islands. Latest satellite
water vapor imagery clearly depicts a sub-tropical jet just north
and west of Kauai producing two distinct upper-level lows; one on
either side of the Hawaiian Islands. The more mobile low west of
the islands will begin to dig southwestward away from the state,
resulting in little impact. Conversely, the more intrusive,
eastern low will result in a bit of instability, which may produce
some brief enhanced shower activity focused over predominately
windward and mauka areas.

Additionally, a well-defined band of moisture can be seen on
satellite imagery is anticipated to bring showers mainly to
windward areas of Big Island and Maui initially this morning.
However, trends displayed on an American model (GFS) cross
section of Hawaii portrays wetter conditions moving up the island
chain to Molokai and Oahu late this morning to early afternoon.
Overall precipitation accumulation will be on the lighter side,
but some locations may fetch a tenth to upwards of a quarter of an
inch of rainfall.

Model guidance of the GFS and European model (ECMWF) show the
aforementioned low eventually strengthens and forms a closed low
tomorrow, and slowly meanders away from the Hawaiian Islands.
Ridging quickly builds in in its wake, allowing dry and stable
conditions to return. This will open the doors to moderate trades
reestablishing, with the more typical trade showers across
windward and mauka areas with exception for the Kona slopes of
the Big Island, where typical sea-breeze induced cloud buildups
and showers will be possible during the day.

Toward the latter end of the week, model guidance introduces a
front moving northwest to southeast. As this occurs, background
surface winds will become light and veer southeasterly, allowing
for daytime sea breezes and nighttime land breezes ahead of its
arrival. There`s still a fair bit of uncertainty with regards to
the timing of the front, as the ECWMF displays a much earlier
arrival time compared to the GFS. Furthermore, ECMWF shows the
front to have a more modest impact to the Hawaiian Islands,
dissipating apart much quicker. GFS, on the other hand, supports
the likeliness of enhanced shower activity as it passes through.
Further analysis will be needed to determine which scenario proves
more favorable in the forecast guidance over the coming days.


&&

.AVIATION...

Light to moderate trades will persist throughout the day and will
bring periods of showers to windward and mauka areas. A band of
moisture east of the islands will also move westward through the
early portion of today, bringing enhanced showers, mainly across
windward areas, but may trickle into the leeward and interior
portions of the state. Brief MVFR conditions remain possible with
passing showers. Otherwise VFR conditions prevail.

AIRMET Tango remains in effect for moderate turbulence between
FL290-FL360 extending from Kauai to Maui.


&&

.MARINE...
A surface high pressure ridge will remain north of the Hawaii
region, winds flowing around this ridge will produce gentle to
moderate easterly winds today, then decreasing and veering more
southeasterly to southerly from Tuesday to Wednesday as another
cold front moves into the region from the northwest. A consensus
of weather model guidance suggests this cold front may move into
the western Hawaiian islands from late Wednesday into Thursday,
then diminishing by Friday.

The current medium period north-northwest (340-350 degree) swell
continues to slowly fade into Monday, bringing surf back down to
below average levels for this time of year. The next two long to
medium period overlapping northwest (310-320 degree) swell pulses
will arrive on Monday and Tuesday, boosting surf along north and
west facing shores and possibly reaching marginal advisory levels
by Wednesday.

Choppy east shore surf will remain small and decline for the next
few days as trades gradually ease. Expect minimal background
energy for south facing shores keeping south shore surf heights
above flat levels.

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 through the peak high tide this morning.


&&

.FIRE WEATHER...
Light to moderate trades and relative humidity values in the low-
to mid-50s will maintain below critical fire weather thresholds
through much of this week. Winds are expected to ease further as
the week progresses preceding a wetter weather pattern during the
latter half of the week. The morning temperature inversion
heights sloped from around 6500 feet at Lihue to around 10000 feet
over Hilo.


&&

.HFO WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$


DISCUSSION...Pierce
AVIATION...Pierce
MARINE...Bohlin
FIRE WEATHER...Pierce