Drought in Hawaii, May 1 to 31, 2025

Area Forecast Discussion
National Weather Service Honolulu HI
845 PM HST Wed Apr 30 2025

.SYNOPSIS...
Strengthening trade winds will be locally breezy into next week.
Brief showers will favor windward and mauka areas, and leeward
areas will be mostly dry.

&&

.DISCUSSION...
A persistent trough NW of Kauai will weaken and move W while
strengthening high pressure will pass well N of the islands. Trade
wind speeds will continue to increase, with locally breezy E winds
expected into the weekend. Some subtle weakening and veering in wind
direction (to the ESE) may occur late this weekend as the high moves
far NE of the islands, and a front passes to the NW. Early next
week, a new, strong high is expected to build well N of the islands
as the front stalls, leading to increased trade wind speeds.

Troughing aloft will continue to move E and away from the islands,
with a building mid-level ridge leading to increased stability. As a
result, just a few brief windward showers are expected through the
weekend. Weak troughing aloft may return next week, potentially
leading to an increase in windward showers. Leeward areas will start
the dry season with limited rainfall, except for a few afternoon
showers over the Kona slopes.

In the short term, limited windward showers are expected overnight,
except over windward Big Island, where a clump of showery low clouds
arriving on the trades will make for a wet evening in many areas.

&&

.AVIATION...
Trade winds have started to develop across the state this evening
and look to prevail through the forecast period. VFR conditions will
prevail with spotty MVFR conditions focusing clouds and showers over
windward and mauka areas.

AIRMET Sierra has been issued for mountain obscuration for windward
Big Island. Conditions are expected to improve through late tonight
as winds shift from onshore to offshore.

No other AIRMETs are in effect.

&&

.MARINE...
High pressure approximately 1,200 nautical miles northwest of the
islands will travel east and be north of the state by late
Thursday...northeast of the area this weekend. The pressure gradient
between the high and lower equatorial pressure will be tight enough
to produce high end moderate/fresh to locally strong trade winds
from as early as Thursday afternoon through most of next week.
Several days of Small Craft Advisory (SCA) level winds will occur
over the notoriously windier channels and bays surrounding Maui
County and south of Big Island that will commence Thursday.

A relatively small size, moderate to long period north northwest
swell has arrived at the far northwest buoys this afternoon and will
be passing around the islands through the early Thursday morning
hours. This swell will peak late Thursday then slowly decline this
weekend. A series of northwest to north swells are expected next
week that should produce near or above seasonal average (6 foot)
surf.

A small, long period south southwest swell will continue to fill in
tonight and peak Thursday into Friday. This latest swell will result
in above summer average surf heights before slowly fading this
weekend. A mix of both a reinforcing south southwest swell and new
long period south southeast swell energy this weekend should this
near to above average (5 foot) surf. South-facing shore surf will
generally decline next week, but smaller south southwest swells will
hold surf near summer averages through the middle of next week.

Recent upstream trade winds will keep east-facing shore surf on the
small side. An increase in east wind wave chop is expected on Friday
as the trade winds pick up a notch over and upstream of the state.

&&

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

&&

DISCUSSION...Birchard
AVIATION...Shigesato
MARINE...Blood