Wildfire in Hawaii, July 22, 2024

Area Forecast Discussion
National Weather Service Honolulu HI
323 AM HST Mon Jul 22 2024

.SYNOPSIS...
Moderate to locally breezy trade winds will focus showers over
windward slopes today, and aside from afternoon and evening
showers on the Kona slopes, leeward areas will be rather dry. An
area of moisture will spread over the islands tonight and
Tuesday, bringing an increase in shower activity into Wednesday.
Trade winds will increase and showers will decrease late Wednesday
and Thursday.

&&

.DISCUSSION...
Moderate to locally breezy trade winds and a typical pattern of
mainly windward showers will prevail today. A rather strong 1034
mb high is centered about 1400 miles north of the state. A trough
south of the high will keep the pressure gradient and associated
trade winds slightly weaker than would be expected with a high of
this strength. A weak upper-level trough just west of the islands
is sending thin high clouds over the western end of the island
chain and is enhancing a few heavy showers south and west of
Kauai. However, the combination of stability from a mid-level
ridge over the islands and a pocket of drier low-level air moving
in from the east will produce modest windward rainfall today.
Aside from scattered afternoon showers over leeward Big Island,
leeward areas will be mostly dry.

An increase in shower activity is due tonight into Wednesday as a
moisture pooled around a mid-level trough moves in on the trades.
Precipitable water between 1.5 to 1.8 inches mainly below 12,000
feet will fuel an increase in windward rainfall, and leeward
slopes of the Big Island, and possibly Haleakala, will likely be
active each afternoon, while leeward areas elsewhere will
experience a few passing showers.

Drier conditions and stronger trade winds will develop Wednesday
and Thursday as the mid-level trough moves away and the high to
the north builds. Expect minimal windward rainfall and dry
conditions over most leeward areas. Trade winds will ease during
the weekend.

&&

.AVIATION...
Moderate to locally breezy trades will continue and gradually
strengthen through the next few days. Clouds and showers will
favor windward and mountain areas, especially overnight into the
early morning hours. In addition, clouds and showers will build up
on the Kona slopes of the Big Island each afternoon. An area of
enhanced moisture could bring a modest increase in clouds and
shower coverage later tonight into tomorrow. MVFR conditions will
be possible with any of this shower activity.

No AIRMETs are currently in effect although AIRMET Sierra could be
needed later tonight for windward and mountain areas as increased
moisture moves through.

&&

.MARINE...
A high pressure system far north of the Hawaiian Islands will
keep trade winds in the fresh to locally strong range through much
of this week. Trade wind speeds will remain strong enough to
support Small Craft Advisory (SCA) conditions over the windier
waters and channels near Maui and the Big Island through the end
of the week. The current SCA was extended in time for these
windier waters out through Tuesday night. Additional waters will
likely be added later this week as wind speeds increase.

Background south swell energy pulses are forecast to continue,
with surf remaining below average through much of this week. A
small long period south swell may produce a slight increase in
south shore surf heights on Thursday and Friday. Small, choppy
surf will build along east facing shores as locally strong trade
winds increase over the next few days.

Local tide gauges are still showing water levels running about a
half a foot above coastal flooding guidance at Hilo, Kahului, and
Honolulu. The Coastal Flood Statement for isolated minor flooding
remains in effect through this afternoon.

&&

.FIRE WEATHER...
A typical summer trade wind weather pattern will prevail today,
followed by wetter conditions tonight into Wednesday. Late
Wednesday and Thursday, trade winds will strengthen, and somewhat
dry and stable conditions will develop. This could lead to some
fire weather concerns Thursday and possibly Friday.

&&

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

&&

DISCUSSION...Wroe
AVIATION...Tsamous
MARINE...Bohlin