FXHW60 PHFO 041945
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
945 AM HST Wed Dec 4 2024

.SYNOPSIS...
The combination of southerly winds, moisture ahead of an
approaching front, and upper troughing will increase rainfall
chances for portions of the state later today through the second
half of the week. The front will reach Kauai on Thursday, then
stall and begin to diminish near Oahu Thursday night into Friday.
Breezy north-northeast winds will fill in behind it Thursday and
Thursday night. Trades will return briefly on Friday. A second
front passing north of the area over the weekend could cause trades
to weaken again.

&&

.DISCUSSION...
Rainfall will increase today through tonight as upper troughing
digs southward into the area. Southerly winds and lift ahead of
an approaching front could trigger pre-frontal showers today,
especially through the late morning and afternoon hours for the
western end of the state. Radar and satellite loops show this
potential, with increased cloud cover and developing showers
noted over waters around Oahu and Kauai. Instability will
increase tonight over and around Kauai as the front draws closer.
Although chances remain low, a thunderstorm or two can't be
completely ruled out tonight into Thursday, especially over the
waters north of Kauai.

Models show the front will stall and slowly diminish around Oahu
Thursday night through Friday as the upper trough lifts
northeastward and away from the area. Breezy north to north-
northeast winds behind the front Thursday and Thursday night over
the western end of the state will veer out of the east on Friday.
This will push residual frontal moisture westward. A brief return
of light trade winds is possible over the weekend as another
front passes to the north.

&&

.AVIATION...
High stability sea breeze pattern continues through today with
just a few afternoon clouds over island interiors anticipated.
Land breezes will bring clearing tonight for most areas. A
dissipating cold front will bring increasing southerly flow and a
band of showers likely resulting in MVFR over south-facing slopes
of Kauai late tonight into early Thursday.

No AIRMETs in effect. AIRMET Sierra will likely be needed for
portions of Kauai late tonight into early Thursday morning.

&&

.MARINE...
A near east-to-west surface ridge axis laying across the waters is
supporting statewide light to gentle variable breezes, more south
southwest over the Kauai and Oahu coastal waters, southeasterly
around Big Island. There will be little deviation to these light
winds through the day in response to the near stationary ridge.
The eastern passage of an upper trough to the north will displace
ridging to the East Pacific Friday. It will also push a surface
cold front into the local western waters. This front is timed to
reach Kauai's nearshore waters Thursday morning and stall out
somewhere over the central waters Friday into Saturday. Thus,
expect strong north northeast post-frontal winds to impact Kauai's
surrounding waters Thursday during the day with northerly winds
significantly dropping off as the front passes in the vicinity of
Oahu Thursday evening. The approaching front will introduce a
slight chance of thunderstorms for the waters surrounding Niihau,
Kauai and the Kauai Channel. Winds and/or seas will likely reach
Small Craft Advisory (SCA) criteria Thursday and Friday, focused
over the western half of the state, from the frontal passage in
tandem with a passing northwest swell. The front will weaken as it
becomes more zonal in direction Friday afternoon. Gentle to
moderate trade flow will establish itself going into Saturday.
Trades will strengthen to fresh to locally strong magnitudes by
next Tuesday into Wednesday as surface high pressure builds in
northeast of the island chain.

The High Surf Advisory (HSA) for exposed north and west facing
shores has been cancelled. In the short term, shorter period
north northwest swell around the northwest offshore buoys have
slightly diminished this morning. This short period, near 7 foot
swell swell will hold through the next north northwest swell
arrival tomorrow. Long fetches produced within very large areas of
near-gale to gale-force winds in association with low pressure
systems passing far north of the area will send north to northwest
swell of varying sizes and periods toward the islands the next
several days. Most of this swell energy will be confined to the
relatively shorter period bands. Resultant surf is expected to be
near or above HSA heights along exposed north and west-facing
shores going into the weekend.

A long period, very small south swell will gradually decline
through Thursday. Another similar south swell is expected from
Friday afternoon through the weekend, but it will may come in a
touch smaller than this most recent swell.

&&

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

&&

$$

DISCUSSION...Powell
AVIATION...JVC
MARINE...Blood