817
FXHW60 PHFO 130100
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
300 PM HST Sun Apr 12 2026

.SYNOPSIS...
Light to moderate rain will continue through tonight over the
western portion of the state. A few showers may be locally heavy.
Quieter weather then settles in for the remainder of the week and
light trades return by week`s end.

&&

.DISCUSSION...

Nil instability, weak forcing, and rather high mid-level static
stability have allowed Oahu to dodge a potentially impactful
flooding event. Little change is expected during the next several
hours, so rain rates are expected to remain in check. Cancelling
the Flood Watch for Big Island. Will draw back the ending time
for Kauai through Maui to 6am tomorrow morning. Elected to retain
portions of the Flood Watch to account for the onset of the
favorable diurnal cooling period and ongoing convection in Maui
County within the surface trough axis. As forcing weakens, so too
will rain rates. Light showers and mid-level clouds are likely to
linger over the western end of the state for the balance of the
week before another shortwave pivots through and brings a slight
uptick in rainfall on Friday or Friday night. This wave is modeled
to be progressive and and likely not impactful.

Despite the grungy pattern that may hang over Kauai and Oahu through
the week, for the first time in awhile, there is no potential event
on the horizon. The large scale pattern is gradually migrating away
from aggregate low pressure anchoring north of the islands, though
high pressure struggles to build as the mid-latitudes transition
toward a more progressive pattern. Light winds favoring onshore
sea breezes each afternoon may trigger rather productive
convection in terms of showers as the moisture-rich airmass
lingers. Likewise, dewpoints will hover around 70 degrees until
the dregs of this airmass are ushered westward by returning
trades. Trades do return by late this week, but remain quite
light and may not make much of a dent in local humidity.

&&

.AVIATION...

Showers continue to move in over the islands this afternoon.
Kauai and Oahu are still expected to bear the brunt of this
system`s impact, however radar shows showers popping up over Maui
County as well. Shower activity is still expected to simmer down
this evening, however MVFR or worse conditions may still arise
across several sites due to lingering moisture and low clouds.
Winds will remain light at less than 10 kts, with land-sea breeze
direction at most sites.

AIRMET Sierra remains in effect for mountain obscuration above
1500 ft for Kauai, Oahu, Molokai, and Maui, as well as for IFR
conditions at Lanai. These conditions are expected to remain
today with the ongoing shower threat, with some relief expected
later this evening as conditions dry out, however low clouds may
remain due to light winds and lingering moisture.

AIRMET Tango is also in effect for 120-FL280, as this system is
expected to create moderate turbulence as it passes over the
islands. Conditions are expected to improve overnight heading
into Monday.

Widespread cloud cover over the state today may also lead to
moderate icing.

&&

.MARINE...

A weak surface trough will linger in the vicinity of the central
and northwestern islands into early next week, keeping moderate
to fresh southeasterly winds to its east, and light to moderate
southerly winds to its west. This weak surface boundary along
with an upper level disturbance moving over the region is
currently bringing another round of showers and the potential for
isolated thunderstorms this afternoon into Monday. As the surface
trough lifts northwest and high pressure to the northeast begins
to take over at the surface, gentle to moderate easterly trades
will gradually develop across the Hawaiian coastal waters by the
end of the week.

A moderate, medium-period north-northwest swell (340 degrees)
generated by the formerly-gale force low north-northwest of the
main Hawaiian islands is filling in along north and west facing
shores this afternoon. This swell will maintain small to moderate
surf through Monday, followed by a decline in northwest swell
energy for the rest of the week.

A medium-period south swell will continue to decline through Monday.
By Tuesday, however, a new south swell will arrive, once again
providing a boost to surf along south facing shores through mid week
before gradually subsiding into the weekend.

Surf along east facing shores will remain below seasonal average
with lighter than average trade winds near and upstream of the
islands forecast through next week.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Flood Watch through tonight for Niihau, Kauai, Oahu, Molokai,
Lanai, Maui, and Kahoolawe.


&&

$$

DISCUSSION...JVC
AVIATION...Evans
MARINE...Farris