448
FXHW60 PHFO 241314
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
314 AM HST Fri May 24 2024

.SYNOPSIS...
A high pressure ridge north of the islands will keep moderate to
breezy easterly trade winds over the islands, peaking today and
then decreasing slightly into the middle of next week. Clouds and
showers will favor typical windward and mountain areas, trending
higher in the overnight to early morning hours.

&&

.DISCUSSION...
Satellite imagery this morning continues to show a large band of
high level cirrus clouds produced by the subtropical jet stream
are spreading over the Hawaii region from west to east today.
Fairly stable low level clouds are drifting over the islands in
moderate to breezy easterly trade winds. These high level cirrus
clouds may enhance sunrise and sunset colors through the weekend.

Trade winds will continue to blow across the Hawaiian Islands at
moderate to breezy levels through much of next week. Breezy wind
speeds will peak today as the high pressure ridge builds in
slightly, and then decrease slightly by this weekend as the
surface pressure gradient weakens a bit. Trade winds will drive
clouds up and over windward island mountains into the middle of
next week. Brief periods of showers remain in the forecast mainly
over these windward and mountain areas, trending higher in the
overnight to early morning hours. Drier leeward areas will see
less clouds and only isolated showers due to the subsidence caused
by the down sloping trade winds immediately leeward of the
eastern mountain ranges of each island. Drying and warming effects
produced by this small scale atmospheric compression tends to
keep leeward areas more stable and dry in typical trade wind
weather patterns.

Only subtle changes are expected in the day to day weather
forecast for each island in a fairly stable trade wind weather
pattern. Weak upper level troughing north and west of the island
chain will bring a slight increase in passing shower activity this
weekend, mainly over windward areas in the overnight to early
morning time periods. The highest chances for clouds and showers
statewide will linger over eastern Maui near Hana, and over the
eastern slopes of the Big Island from the Hamakua Coast to Hilo
to the Puna District.

&&

.AVIATION...
Moderate to breezy easterly trade winds will persist across the
Hawaiian Islands into the weekend. Isolated to scattered showers
will favor windward coasts and slopes, with greater coverage
expected during the overnight hours. Brief MVFR conditions are
possible in moderate showers. Otherwise, VFR conditions will
prevail.

AIRMET Sierra for mountain obscuration remains in effect for
windward areas of Kauai, Oahu and the Big Island this morning.
Conditions may improve later today, but an uptick in windward
showers tonight may require AIRMET Sierra once again. No other
AIRMETS are in effect and none are expected.

&&

.MARINE...
High pressure will gradually build westward well to the north of
the state today and tonight, keeping fresh to strong trade winds
in place across the island chain. A Small Craft Advisory (SCA)
remains in effect for most waters around Maui County and the Big
Island as well as the northwest Kauai waters through 6 AM
Saturday. For the windiest waters around Maui and the Big Island
the SCA extends through 6 PM Saturday. A trough of low pressure
will amplify and linger west of the islands this weekend into
early next week, resulting in a slight easing of the trades and a
shift to a more east-southeasterly direction over the western end
of the state. Moderate to locally strong easterly trades will
prevail over the eastern waters.

South shore surf will remain small and below the summer average
through the middle of next week, with only small and inconsistent
pulses of southwest swell expected. The next significant south-
southwest swell (200 deg) appears to move in toward the end of
next week. East shore surf will remain near the seasonal average
through Friday, followed by a slight decrease this weekend through
the middle of next week as the trades ease over and upstream of
the islands. Surf along north shores will remain very small with a
slight bump possible late Sunday through Monday.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 AM HST Saturday for Kauai Northwest
Waters-Kaiwi Channel-Maui County Windward Waters.

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

&&

$$

DISCUSSION...Bohlin
AVIATION...Powell
MARINE...Jelsema