FXHW60 PHFO 170132
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
332 PM HST Fri Oct 16 2026

.SYNOPSIS...
Moderate to breezy trades will gradually strengthen through early
next week, then weaken over the latter half. Brief pulses of 
enhanced showers will roll through on the trades during this time 
period, with showers favoring windward and mauka areas in the 
overnight to early morning hours. 

&&

.DISCUSSION...
Radar and satellite imagery show isolated to scattered showers 
moving into mainly windward and mauka areas of the state this 
afternoon, with shower coverage increasing over the eastern half 
of the state as a plume of deeper moisture moves in on the weakly 
convergent trade wind flow. This uptick in windward shower 
activity will work its way up the island chain and persist into 
the evening hours before drier air fills in on Saturday. 

Surface high pressure to the north will build through the weekend
and strengthen the trade wind flow to breezy levels through early
next week. Additional batches of increased moisture will continue
to filter in on the trades over the next several days and bring 
brief upticks in windward and mauka shower activity, particularly 
during the overnight to early morning hours. Overall, these 
showers may produce brief moderate downpours at times, but they 
will move through rather quickly, so flooding is not expected to 
be an issue.

Both aloft and at the surface, broad and weak troughing will 
gradually develop over the Central Pacific by midweek, weakening
the pressure gradient and therefore decreasing the trade wind
speeds. Otherwise, periodic showers will continue to filter into
windward and mauka areas on the weakening trade wind flow. 

By next weekend, models are hinting at more substantial 
instability developing aloft and a larger area of deep tropical 
moisture being drawn up from the southeast, possibly leading to
the potential for widespread heavy showers. However, the window
with the greatest potential for any impacts is beyond the 
forecast period and with the model discrepancies that far out,
forecast confidence is on the lower side for that period.

&&

.AVIATION...
Gusty trade winds will continue today into tomorrow. Shower 
coverage will increase from east to west during the next 24 hours,
initially favoring windward portions of the Big Island and Maui, 
then spreading toward Oahu and Kauai tonight into tomorrow. Brief 
MVFR ceilings and visibility are expected in passing showers, with
VFR conditions prevailing between showers.

AIRMET Sierra may be needed tonight as increasing shower coverage
may bring renewed mountain obscuration. 

AIRMET Tango remains for moderate low level turbulence downwind 
of island terrain. 

&&

.MARINE...
Surface high pressure far north of the islands will strengthen as
it drifts eastward through Saturday. Reinforcing high pressure 
will build far north of Hawaii on Sunday and will settle far 
northeast of the islands through early next week. Fresh to strong
trade winds will prevail during this time, and the Small Craft 
Advisory (SCA) for the typically windy waters around Big Island 
and Maui may need to be expanded to additional waters this 
weekend. Trades are expected to ease slightly by Wednesday.

A medium-period north-northwest swell will peak overnight,
producing north shore surf around seasonal average. This swell 
has been slow to arrive today, with measurements at NOAA buoy 
51001 recently coming in at 5 to 6 feet at 11 to 12 seconds. This 
swell will slowly decline and shift more northerly during weekend 
as a smaller overlapping northwest swell moves through the area. 
Both swells will lower on Monday and fade on Tuesday. Another 
small northwest swell is possible next Thursday or Friday.

Long period south swell will peak through this evening, producing
south shore surf slightly above seasonal average. This swell will
gradually decline this weekend, and surf along south- facing 
shores will below average through the coming work week.

Surf along east-facing shores will gradually increase over the
next couple of days as trade winds strengthen over the region. 
In addition, expect some wrapping north-northwest swell to reach 
exposed areas through at least Saturday. Rough trade wind swell 
will produce east shore surf above seasonal average Sunday through
Tuesday, followed by a decline Wednesday.

&&

.FIRE WEATHER...
Surface high pressure far north of the islands will produce 
moderate to breezy trade winds for the next few days, with gradual
strengthening expected through early next week. Between batches 
of showers rolling through on the trades, RH levels may approach 
critical fire threshold ranges, particularly Saturday afternoon. 
Otherwise, RH levels should help to maintain low to moderate fire 
weather concerns.

Inversion heights should increase to around 10,000 feet through
tonight as the current batch of deeper moisture rolls through,
then drop to 5,000 to 7,000 feet on Saturday.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 AM HST Monday for Alenuihaha 
Channel-Big Island Leeward Waters-Big Island Southeast Waters-
Maalaea Bay-Pailolo Channel.

&&

$$

DISCUSSION...Farris
AVIATION...PECHACEK
MARINE...Wroe
FIRE WEATHER...Farris