Heavy Rain in Hawaii, January 5, 2022

Area Forecast Discussion
National Weather Service Honolulu HI
945 AM HST Wed Jan 5 2022

.SYNOPSIS...
Light and variable winds, and mostly dry weather, will prevail into
next week. Generally speaking, this will allow skies to clear at
night, with afternoon and early evening interior clouds bringing the
chance of a few showers. A weak front stalling and dissipating over
the area this weekend may bring a subtle increase in clouds and
showers to Kauai and Oahu on Saturday.

&&

.DISCUSSION...
A mostly dry, light wind weather pattern is expected to persist into
next week. A mid-level ridge building over the area from the W will
lead to a stable island atmosphere, strongly limiting shower
coverage and intensity. A surface ridge near the islands will
support the light wind regime.

Although there may be some subtle variations in our day-to-day
weather as fast-moving features pass N of the area, the light winds
will largely allow island-scale circulations to drive the weather
over land. Land breezes will lead to mostly clear nights and
mornings while converging sea breezes will drive cloud formation
over island interiors during the afternoon and early evening, with a
few showers possible.

Some of the features that may interrupt the land-sea breeze weather
pattern include a weak high passing N of the area tonight that will
turn the light winds to the N and NE into Thursday, potentially
bringing a few windward showers before winds go variable again.
Also, a surface trough about 600 miles SE of the Big Island will
move slowly W, and may bring some increased cloudiness and a few
showers to windward Big Island Thursday night and Friday before
retreating eastward. This trough may also bring a brief period of
moderate NE winds to waters around the Big Island. Also, a weak
front moving into the area from the NW on Saturday may lead to a
short period of light to moderate NW to N winds, while also bringing
a subtle increase in showery low clouds that diminishes by Sunday.

&&

.AVIATION...
A weak cold front approaching the state from the northwest has
shifted low level flow to be out of the southwest. The southwest
flow will carry a few scattered showers towards the islands, but
will be weak enough to allow local wind effects to predominate over
the next twenty-four hours. Light sea breezes will focus afternoon
and evening shower activity over island interiors. Weak land breezes
will promote overnight clearing. High pressure building in northeast
of the state will act to stabilize the air mass, but isolated MVFR
CIG and VIS in moderate showers remain possible today.

No AIRMETs are currently in effect or anticipated at this time.

&&

.MARINE...
As a cold front to the west of the state lifts northeast of the
islands, winds will weaken to light and variable through the day.
A high passing to the north of the area will allow for the brief
return of gentle north to northeast trade winds tonight through
Thursday. Upper ridging to the east will support a stable air mass
and drier weather for the latter half of the week. Another cold
front may reach the far northern offshore waters this weekend and
veer winds back around to the north. The passage of a large north
swell and a couple of large northwest swells will assist in
producing significant seas at or above the 10 foot Small Craft
Advisory threshold over exposed, windward waters through Thursday
afternoon and then again this weekend.

A large, long period north swell arrived last night, coming in well
above model guidance, especially at the Hilo nearshore buoy which
has been hovering around 10 to 11 feet for the last several hours.
As a result, have added north facing shores of Maui and the Big
Island to the High Surf Advisory. A large northwest swell is hitting
the far northwest buoys this morning and should reach Kauai later
this afternoon, Oahu, this evening, and Maui County tonight. The
combination of these two swells will generate High Surf Advisory
(HSA) surf along north and west facing shores of Niihau, Kauai,
Oahu, and Molokai, as well as north facing shores of Maui and the
Big Island. The Big Island should drop from the HSA later tonight as
the north swell fades. A long fetch will develop far northwest of
the islands later this week that will push in an even larger
northwest swell this weekend. This swell could produce warning level
surf along most north and west facing shores.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory until 6 PM HST Thursday for North and West facing
shores of Niihau Kauai Oahu and Molokai and for North facing shores
of Maui and the Big Island.

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

&&

DISCUSSION...Birchard
AVIATION...Bedal
MARINE...TS