Drought in Hawaii, December 1 to 31, 2024

Area Forecast Discussion
National Weather Service Honolulu HI
848 PM HST Sat Nov 30 2024

.SYNOPSIS...
Trade winds will weaken by Sunday allowing land and sea breezes
to develop over all islands. Conditions should remain fairly
stable and dry, with low clouds and a few light showers each day
favoring interior and mountain locations. Rainfall trends will
increase from Thursday into Friday as a weak cold front moves into
and stalls out over the islands. Periods of passing showers will
linger into next weekend.

&&

.DISCUSSION...
This evenings satellite image shows a subtropical jet stream
near the Big Island. High level cirrus clouds have drifted south
of the island chain. Bands of stable clouds remain just east of
the islands moving into windward slopes on the weakening trade
winds tonight. This trade wind weather pattern will change on
Sunday into variable winds in a land and sea breeze regime over
all islands.

The subtropical ridge axis currently over the islands keeping
fairly stable conditions in the forecast will drift south of the
state from Sunday onward. Expect a slight increase in shower
trends during the first half of next week in a light wind
afternoon onshore sea breeze weather regime. Clouds and a few
showers will develop by late morning to afternoon over island
mountain and interior sections through Wednesday. Rainfall amounts
will remain on the lighter side due to the large scale atmospheric
stability.

By Thursday, long range model guidance continues to show a shallow
cold front creeping into the western islands from the northwest
direction. Widespread showers and breezy trade winds will develop
along the weakening frontal band as it passes through each
island. The latest model guidance continues to show this frontal
cloud and shower band stalling out near Maui by Friday morning.
All islands will benefit from a period of enhanced showers along
the frontal band, especially along the windward and mountain
slopes of each island. The frontal band will then break apart by
Friday afternoon, with remnant unstable cloud bands drifting into
each island on the strengthening easterly trade winds, producing a
wet trade wind pattern lasting through much of next weekend.

&&

.AVIATION...
Light to locally moderate trades will continue to weaken through
the rest of the weekend, allowing for land/sea breezes development.
Isol SHRA should favor mauka and interior areas of each island
due to sea breeze development each afternoon, then clear out
overnight with the land breezes. Brief MVFR conds will be possible
in SHRA, otherwise VFR should prevail.

AIRMET Tango is in effect for mod turb between FL250 and FL450
across the state.

SIGMET Papa for severe upper level turb is also in effect across
the eastern half of the state. This will likely taper off from
west to east through the night into tomorrow morning as the
subtropical jet pushes east of the area.

&&

.MARINE...
A front stalled north of the coastal waters keeps our local
pressure gradient slack and background winds light across the
area this evening. Light background flow will shift to
southeasterlies on Sunday. Another front will approach from the
northwest early next week and keep gentle south to southeast
winds in place.

The extra-large northwest (310-320) swell that peaked last night
continues to slowly decline this evening. However, based on buoy
data and shore observations, the High Surf Warning for most north
and west facing shores of the smaller islands remains in effect
through midnight tonight. A High Surf Advisory (HSA) remains in
effect for west facing shores of the Big Island through tonight.
Surf should drop below advisory levels by Sunday afternoon.
Additionally, a Small Craft Advisory (SCA) remains in effect for
windward waters and all waters surrounding Kauai County for seas
greater than 10 ft through tonight.

A stretch of elevated north and west shore swell is expected,
produced by overlapping northwest pulses ranging from large to
potentially extra-large, with the first arriving Tuesday and a
larger one peaking Wednesday into Thursday. Surf along east facing
shores will remain slightly elevated through the rest of the
weekend due to the lingering short-period north-northeast swell.
Early next week, surf along east facing shores will remain small.
Surf along south facing shores will see an uptick heading into
next week from a series of consecutive southwest pulses. This will
result in small to moderate surf, peaking Monday and Tuesday.

&&

.FIRE WEATHER...
Critical fire weather conditions are not expected through early
next week as winds remain below warning thresholds. Daytime
relative humidity may briefly touch critical levels over drier
leeward zones into next week. Increasing moisture and rainfall trends
will develop from Thursday into next weekend as a weakening cold
front moves down the island chain and stalls out near Maui.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Warning until midnight HST tonight for Niihau-Kauai
Leeward-Waianae Coast-Oahu North Shore-Maui Windward West-Kauai
North-Koolau Windward-Molokai Windward-Molokai North-Molokai
West-Windward Haleakala.

High Surf Advisory until 6 AM HST Sunday for Kona-Kohala.

Small Craft Advisory until 6 AM HST Sunday for Kauai Northwest
Waters-Kauai Windward Waters-Kauai Leeward Waters-Kauai Channel-
Oahu Windward Waters-Kaiwi Channel-Maui County Windward Waters-
Big Island Windward Waters.

&&

DISCUSSION/FIRE WEATHER...Bohlin
AVIATION...Walsh
MARINE...Powell