830
FXHW60 PHFO 011305
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
305 AM HST Tue Oct 1 2024

.SYNOPSIS...
Moderate east to east-southeast winds will continue with passing
windward and mauka showers into Wednesday. Winds are expected to
weaken Thursday into the weekend, that will support afternoon sea
breezes and overnight land breezes. Moderate trades may return
early next week.

&&

.DISCUSSION...
The PoPs have been nudged downwards, following the trend of the
National Blend of Models. Winds have also been nudged downwards
following a blend of the GFS and ECMWF for the longer range for
the background flow.

High pressure remains far to the northeast, with a ridge north of
the islands overnight. The overnight ASCAT-B pass captured east-
southeast winds near the Big Island, while winds near Maui County
were more easterly. Little change in wind speeds upstream of the
islands.

Earlier runs of the GFS and ECMWF showed an upper level low west
of the islands moving east and weakening on Wednesday. The latest
run has an even weaker upper level low, so it will likely have
minimal impact on the local weather.

North of the above mentioned ridge, and to the north-northwest of
Kauai, a low pressure system is moving to the northeast. Its
associated front will move slowly to the northeast and linger,
helping to disrupt the ridge. This will lead to a weakening of the
trades during the second half of the week, resulting in some
afternoon sea breezes and overnight land breezes. This pattern
will bring some afternoon clouds and showers over the interior of
the islands, with some clearing overnight. The models suggest the
showers may still favor windward areas.

The GFS continues to show an upper level trough digging south
towards the islands Saturday, but the latest run of the ECMWF has
backed off significantly. At the surface, a ridge begins to re-
establish itself north of the islands that will allow trades to
return.


&&

.AVIATION...
Surface high pressure ridge north of the state will keep moderate
trade winds in the forecast. Expect continued periods of low
clouds and showers, mainly over windward and mountain areas, with
brief MVFR cigs/vis through the overnight to early morning hours.

No AIRMETs are in effect.

&&

.MARINE...
High pressure northeast of the islands will maintain moderate to
locally fresh trades through Thursday. The trades are expected to
ease into the light to locally moderate range Friday and Saturday
as the ridge to the north weakens. A new high building northwest
of the area may restrengthen trades into the moderate to fresh
range Sunday into early next week.

A new medium-period northwest swell will build today, peak near 4
feet tonight, then decline as it becomes northerly Wednesday and
Thursday. A pair of overlapping small short to medium-period north
swells will keep some small surf in place along north facing
shores over the weekend. There is the potential for a much larger
long-period northwest swell Monday, which could bring advisory
level surf to most north and west facing shores.

The current building long-period south-southwest swell will peak
today through Wednesday, then gradually decline during the rest
of the work week. A new and larger long-period south-southwest
swell will gradually fill in late Saturday and Saturday night,
then peak with swell heights of 3 to 4 feet Sunday and Monday.
This swell will give a sizable late season boost to south shore
surf, potentially reaching advisory levels.


&&

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

&&

$$


DISCUSSION...M Ballard
AVIATION...Bohlin
MARINE...Jelsema