Hanapepe Hawaii Weather Forecast Discussion

492
FXHW60 PHFO 070140
AFDHFO
Area Forecast Discussion
National Weather Service Honolulu HI
340 PM HST Mon Oct 6 2025
.SYNOPSIS...
A moisture band will stall over the western half of the state this
evening and remain nearly stationary through Friday. Light
southeast surface winds will become well-established by late
Tuesday, bringing a sea and land breeze dominated regime with it.
This will also last through Friday. Moderate trade winds are
expected to return late Friday and last into next week.
&&
.DISCUSSION...
An area of increased moisture associated with an old frontal
boundary has moved south past Oahu today, spreading showers over
much of the island. Although this band of moisture has not reached
Maui County, there are additional showers there, some strong, and
isolated showers on both Kauai and the Big Island. A mid- to
upper-level low was centered north of the islands this afternoon,
and is forecast to remain nearly stationary through the weekend. This
is contributing a small amount of increased instability to the
picture, resulting in the possibility of stronger showers. Trades
have subsided to a large extent, especially south of the
previously mentioned frontal remnant. By tomorrow, weak southeast
flow will become widespread across the state. This means that our
surface weather will be dominated by afternoon sea breezes and
overnight land breezes.
Precipitation patterns will deviate from the typical windward
maximum and leeward minimum that we see with well-developed trade
winds. Northwest sides of the islands will see a slight increase
in afternoon showers through Thursday and perhaps into Friday.
Trades are forecast to redevelop late Friday into the weekend due
to a very strong surface high off the PacNW coast. This will
return us to more typical weather. Models are not yet clear on
whether or not we will see areas of enhanced moisture next
weekend, but some show the possibility.
&&
.AVIATION...
A decaying trough has been moving through the western end of the
state, with weak winds ahead of the boundary and moderate
northeasterly winds filling in behind it. A band of moisture
associated with this feature is producing prevailing MVFR clouds
and visibilities within showers, with isolated IFR conditions also
possible. Occasional showers with reduced visibility and low
clouds will continue throughout the rest of the afternoon and
evening over the western end of the state, though drier air and
afternoon sea breezes over Maui and the Big Island will give way
to land breezes tonight.
The boundary is expected to wash out by tomorrow where weak
southerly flow will favor sea breeze development during the day.
Though overall drier conditions are expected, the daytime sea
breezes will allow for cloud buildups and a few showers over
interior and leeward locations.
AIRMET Sierra is currently in effect for mountain obscuration for
Oahu, which will likely continue into the evening as lingering
low clouds continue. Otherwise no additional AIRMETs are
anticipated.
&&
.MARINE...
A trough draped from northeast to southwest midway across the
Hawaiian coastal waters is slowing its southeastward descent as it
moves over the Kaiwi Channel this afternoon. Scattered showers
are expected along the trough with moderate northeast trade winds
filling in over Kauai waters, while elsewhere gentle to locally
moderate easterly trade winds are expected through tonight.
Another trough northeast of the offshore waters will slowly drift
west over the next few days. Tuesday through Thursday light to
gentle southeast flow across all zones are expected and will also
give way to localized land and sea breezes. Moderate trades will
fill in from east to west at the end of the weak as high pressure
builds far northeast and drifts southeast.
The current moderate north-northwest swell that peaked well above
High Surf Advisory (HSA) levels Sunday will continue to decline
overnight into tomorrow, producing below average surf along north
facing shores. A small medium to long period northwest (320 deg)
swell is expected to fill in this evening, peak late tonight and
slowly decline Tuesday. However, this northwest swell seems to be
underperforming as only small signals have shown up at the NW
51001 buoy, and only traces of long period swell energy at Waimea
Bay. Either way, below average surf is expected through most of
the week until late this weekend, when a moderate medium to long
period northwest (320 deg) swell is expected to arrive.
A minor small, long-period southwest swell arrived earlier today
and will subside into Tuesday. Another small long-period
southwest (200 deg) swell is possible by the later half of the
week. Surf along east-facing shores will remain below average
through the week.
Peak high tides associated with the lunar cycle will lead to
minor coastal flooding along shorelines and low lying coastal
areas starting Tuesday through the weekend. Coastal flooding will
coincide with the daily peak tide each afternoon. A Coastal Flood
Statement is in effect for all coastal areas through Friday.
&&
.FIRE WEATHER...
Light winds and increased showers will help maintain below
critical fire weather thresholds for the next several days.
Inversion heights across the state will range from 6500 to 7500
feet through tonight.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION...Wroe
AVIATION...Vaughan
MARINE...Farris
FIRE WEATHER...Wroe

NWS HFO Office Area Forecast Discussion