Area Forecast Discussion for Hawaii

Area Forecast Discussion   Issued: 04/30/2026 03:48:00 PM UTC

                        
303
FXHW60 PHFO 300548
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
748 PM HST Wed Apr 29 2026

.SYNOPSIS...

Moderate to locally breezy trades will prevail for the next
several days, resulting in periods of shower activity across
primarily windward and mauka locations. A nearly stationary upper-
level low northeast of the islands will enhance clouds showers
through Friday. By the weekend, the disturbance aloft is forecast
to finally meander farther northeast away from the state.
However, periods of windward and mauka showers will continue.

&&

.SHORT TERM UPDATE...

Minor updates to PoP to account for some scattered showers moving
across the chain. Otheriwse previous forecast remains on track.

&&

.PREV DISCUSSION...
Issued at 358 PM HST Wed Apr 29 2026

This afternoon, moderate to locally breezy trade winds continue
to prevail across the island chain, steered by two areas of high
pressure centered north and northeast of the islands that are
separated by a front that extends from southern Alaska to near
30N. Meanwhile, water vapor imagery shows a distinct low aloft
northeast of the main Hawaiian Islands. This upper-level
disturbance has introduced some instability in the vicinity of the
state, as seen on the afternoon upper air soundings from Lihue
and Hilo. This instability is resulting in deeper clouds and some
enhanced shower activity this afternoon, particularly across
windward sections of Maui and the Big Island. A few showers have
drifted into leeward areas as well, and afternoon sea breeze
convergence has also increased clouds and showers along sheltered
leeward locations, such as the Kona slopes of the Big Island.

Forecast guidance is in good agreement that the upper-level low
northeast of the island chain will remain nearly stationary
through Friday, which will continue a similar wet trade wind
pattern into the next couple of days. Showers will favor windward
slopes of all islands, with some possible shower activity drifting
into leeward areas briefly. However, by this weekend, the upper-
level low will finally exit the region, though periods of showers
will continue to favor windward areas. Only slight variations in
day-to-day trade winds are expected over the next several days,
with slight stenghtening followed by slight weakening this
weekend. By early next week, model guidance shows a shallow cold
front and another upper-level trough approaching the islands from
the northwest early next week, though it remains to be seen how
much moisture can be expected with this system.

&&

.AVIATION...
Issued at 358 PM HST Wed Apr 29 2026

Moderate to fresh trades will strengthen slightly tonight. No
AIRMETs in effect this afternoon, with light leeward turbulence
expected and brief mountain obscurations due to the presence of an
upper low just northeast of Hawaii. A band of showers will move in
with the trades tonight, along with the boost in wind speeds,
will likely result in both AIRMET Sierra for windward tempo
mountain obscurations and AIRMET Tango for leeward tempo moderate
turbulence overnight.

&&

.MARINE...

High pressure strengthening to our north will strengthen the
trade winds Thursday into Friday with widespread fresh to locally
strong trade winds expected by Thursday afternoon. Currently a
Small Craft Advisory (SCA) is in effect for the typical windy
areas of Maui County and the Big Island. The SCA may need to be
extended to other area waters as the trade winds strengthen over
the next 24 to 36 hours. Over the weekend, a front passing far
north of the state will shift the high further east and will allow
the trade winds to decrease below SCA thresholds by Sunday.

A northwest to north-northwest (320-330 degree) will likely peak
tonight into Thursday morning then slowly decline into Friday.
Looking further ahead, a storm-force low currently in the North
Pacific will send a moderate, longer-period northwest swell toward
the islands for late Friday into Saturday, with above average
surf expected along north and west facing shores. Average H1/10
heights for north facing shores is 6 feet for the month of May
(Goddard- Caldwell Database).

Surf along south-facing shores will remain small through the rest
of this work week, with mainly background south to southwest
swell expected. A small south-southwest pulse should arrive this
weekend from recent activity east of New Zealand, providing an
increase in surf especially by Sunday.

Surf along east-facing shores will rise slightly Thursday and
Friday as trades strengthen.


&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 PM HST Friday for Kahoolawe.

Small Craft Advisory until 6 PM HST Friday for Alenuihaha
Channel-Big Island Leeward Waters-Big Island Southeast Waters-
Maalaea Bay-Pailolo Channel.


&&

$$

UPDATE...Walsh
DISCUSSION...Vaughan
AVIATION...Foster
MARINE...Thomas