Area Forecast Discussion for Hawaii

Area Forecast Discussion   Issued: 05/09/2026 05:46:00 AM UTC

                        
097
FXHW60 PHFO 081946
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
946 AM HST Fri May 8 2026

.SYNOPSIS...
Better established light to breezy trade winds will hold well
into next week. While trades are slowly making a come back,
overall large scale winds will be weak enough the next couple of
days to allow localized sea and land breezes to remain the alpha
flow through Sunday morning. This pattern will favor thicker
cloud build up with more frequent daily shower activity primarily
focused over upslope windward mauka interior areas...partially
clearing in the evening per drainage breezes over leeward spots.
A westward passing band of more moisture-rich air, along with
weak instability brought on by the approach of a vicinity eastern
trough or weak area of lower layer convergence, will increase
windward rain probabilities through Saturday evening. Broad
surface ridging developing north of the state will maintain trades
through next week.

&&

.SHORT TERM UPDATE...Most of the state has been dry this morning,
but significant rain has been occurring over the Ko`olau Range.
This rainfall is trending down rapidly, and this downward trend
will continue into the afternoon. A weak surface trough was draped
over/near Big Island, with light winds in the vicinity. For the
other islands, winds were generally light to moderate out of the
northeast. These trade winds will strengthen over the next 24 to
36 hours, and expand to cover Big Island as well as the weak
trough dissipates as it drifts west. No updates are needed at this
time.

&&

.PREV DISCUSSION...
Issued at 359 AM HST Fri May 8 2026

A slug of higher moisture approaching from the east will be
moving across the island chain through the day. Trades are
returning and a benign east southeast flow pattern has become
evident overnight on radar, especially on Oahu. Convergence over
the Koolaus has generated a fair amount of persistent light to
moderate rain with many sites along the windward slopes of Oahu
picking up a half to around an inch of rain since late last night.
A weak circulation, possibly in association with the tail end of a
weak lower level trough approximately 100 miles offshore of Hilo,
is slowly retrograding west. This will decrease regional stability
enough to introduce areas of maritime showers that will
periodically come onshore over windward exposures through
Saturday. Rainfall behavior that was experienced last night along
the spine and windward slopes of Oahu`s higher terrain will be
repeated across other islands through tomorrow as this relatively
more moist air mass advances west northwest up the island chain
through Saturday and produces frequent showers. Higher rain
accumulations will focus across more eastern-facing, or windward,
areas. Cloud cover will gradually thicken up through the day,
especially mid to high clouds originating from ITCZ thunderstorm
cirrus blow off getting caught up within upper level
southwesterlies /subtropical jet traveling over the state. While
trades will make the `feel` of humidity more tolerable, more
overcast afternoon skies will keep many windward (coastal)
communities in the mid to upper 70s while mostly sunny leeward
lighter wind/rain/cloud shadowed locations will warm into the
lower to middle 80s.

Upper level support, or more efficient streamline diffulence, will
be in play...introduced by the subtropical jet passing over the
islands. This strengthens the `more wet than dry` argument in
closing out the first full week of May. Surface troughing
northeast of the islands will be retrograding back into the
central waters through Saturday. This feature, albeit very week,
will likely be the impetus to the regeneration of maritime showers
caught up within the trades that will periodically come ashore
the next few days. Higher rain chances will reside over the
windward sides of islands but leeward areas will also get into the
action from either sea breeze convergence or better organized
cells maintaining their structure enough to wet leeward slopes
along their west southwest journey. A few areas of drier air will
advect in from the east early next week and this help lower
widespread rain episodes Sunday through Tuesday. A more shallow
mid week boundary layer will kick off a few days of more robust
trades focused on Monday-Tuesday through Thursday. Upper ridging
expands in from the northwest by Tuesday with weak troughing
forming west of the state later in the week. This translates to a
more typical seasonal early to mid week trade wind and
precipitation behavior. The timing of when you will receive a
quick dose of rain will strictly be dependent upon when these
eastern bands of higher mid to lower level moisture stream across
the island chain.

&&

.AVIATION...
Local land and sea breezes will gradually return to light to
moderate trade winds tonight, then eventually become locally
breezy tomorrow through the weekend. Clouds and showers are
expected to build up over leeward and interior areas this
afternoon before trade winds push the showers back over the
typical windward and mountain areas tonight. One thing to note is
that the trade winds could be a little stronger over Kauai and
Oahu tomorrow.

VFR conditions will mostly prevail, however some brief MVFR
conditions are possible in any showers that could develop this
afternoon.

AIRMET Sierra for mtn obscuration is in place over Kauai and Oahu
due to lingering showers.

&&

.MARINE...
A weak trough east northeast of the islands will keep trade winds
light to locally moderate across all local waters today. By this
weekend, however, a surface ridge building northwest of the state
will bring a return of moderate to locally fresh trades. A Small
Craft Advisory may be needed for the typical windy waters
surrounding Maui and the Big Island by early next week as the high
expands eastward and trade winds strengthen further.

Surf peaked early this morning along north and west facing shores
according to nearshore buoy data. The Waimea Bay buoy shows
a sustained northwest swell that has reached a plateau since
yesterday afternoon, but swell energy is declining to the
northwest per offshore buoy data. As a result, the moderate,
medium-period, northwest swell will continue to bring elevated
surf to north and west facing shores this morning before slowly
fading today through the weekend.

A small, long-period south swell should provide a small bump in south
shore surf over the next several days.

Surf along east-facing shores will remain slightly below normal
today, due to the lack of strong trades over and upstream of the
islands. East shore surf will gradually increase this weekend into
early next week as trades make a slow return.


&&

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

&&

$$

DISCUSSION...Blood
AVIATION...Tsamous
MARINE...Quesada