Area Forecast Discussion for Hawaii

Area Forecast Discussion   Issued: 05/19/2026 11:41:00 PM UTC

                        
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FXHW60 PHFO 191341 CCA
AFDHFO

Area Forecast Discussion...CORRECTED
National Weather Service Honolulu HI
341 AM HST Tue May 19 2026

.SYNOPSIS...
An unstable and somewhat wet trade wind pattern will continue
through tonight, with brief downpours possible. From Wednesday
into early next week, an area of high pressure north of the
islands will push drier air into the region. Trades are expected
to become windy by Thursday and Friday, then will gradually ease
back to locally breezy levels this weekend.

&&

.DISCUSSION...
Early this morning, local radar imagery shows just a few light
scattered showers moving into the islands on locally breezy
easterly trade wind flow. Similar to the day prior, the heavier
showers that occurred at select spots yesterday quickly diminished
during the late afternoon and evening, leaving only light,
isolated showers favoring windward areas overnight. Regional
satellite imagery early this morning does show a few bands of
moisture upstream of the state, however, and although moisture
content has decreased from the previous couple of days, the early
morning 12z soundings from Lihue and Hilo still show ample
precipitable water available.

Drier air is forecast to arrive from tonight into Wednesday night
as high pressure north of the state strengthens. In the meantime,
expect a relatively wet trade wind weather pattern to continue,
with moderate to briefly heavy rain from showers that will
generally favor windward and mauka areas, as well as the Kona
slopes of the Big Island during the afternoon.

From late Wednesday onward, precipitable water values are
anticipated to decrease back down to around 1 inch, and this drier
air will persist into next week. Increased stability and stronger
trade winds are expected by Thursday. Latest global guidance
remains in good agreement with the high to our north
strengthening, which should result in windy conditions across the
region. Winds could potentially reach Wind Advisory levels
Thursday into Friday for some areas, then decreasing back to
locally breezy levels during the second half of the weekend.

&&

.AVIATION...
Moderate to locally breezy trades expected hold for the next
couple days. Brief periods of low ceilings and showers will
primarily affect windward mountain areas. MVFR conds possible in
heavier SHRA, otherwise VFR prevails.

AIRMET Sierra remains in effect for mountain obscuration for
windward Kauai, Maui and the entire area of the Big Island. These
conditions will diminish later this morning.

&&

.MARINE...
The pressure gradient back from a surface high centered about
1,400 nautical miles northeast of the islands remains tight
enough to support moderate to locally fresh trades the next couple
of days. The anchored high will expand and strengthen through mid
to late week. The resultant very tight gradient back across the
Central Pacific will produce fresh to locally strong to near gale
force nearshore winds the later half of the week. A Small Craft
Advisory (SCA) is currently in effect over the windier zones
surrounding Maui County and Big Island. The SCA will likely be
expanded in area later this week to account for more areawide
strengthened trades.

A small size, short to medium period north northwest swell is
expected to fill in through the day. A gale low skirting the
Aleutian Islands the next couple of days will send the tail ends
of small north northwest swells through late this week.

A series of small, long period south southwest swells will provide
near summer average size surf along south-facing shores throughout
the week. Strengthening trades later this week will keep short
period, elevated eastern wind wave chop alive well into the
weekend.

&&

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

&&

$$

DISCUSSION...Vaughan
AVIATION...Bohlin
MARINE...Blood