902 
FXHW60 PHFO 021402
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
400 AM HST Wed Jan 2 2019

.SYNOPSIS...
High pressure north of the area will maintain moderate to breezy 
trade winds to the islands through Saturday. Clouds and passing 
showers will favor windward and mauka areas with just brief showers 
expected over some leeward locations. Trade winds will begin to 
weaken late Saturday into early next week as a ridge of high 
pressure moves closer to the state.

&&

.DISCUSSION...
Locally breezy trade winds prevail across the state early this 
morning, as provided by the high pressure ridge north of the area. 
Early morning Lihue and Hilo soundings continued to depict a rather 
dry and stable airmass. Comparing the lowest levels winds on the 
Lihue sounding between this morning's and yesterday afternoon's 
hinted a slight decrease in the strength of the trade winds. Latest 
satellite imagery revealed just scattered low clouds in the island 
vicinity. Thus expect another trade wind weather day is instore for 
the islands, with passing low clouds and showers affecting mainly 
windward and mountain areas.

Trades will be lightly weaker today, as a front will pass north of 
the islands. This condition will be short-lived, as another high 
pressure will follow this front from the west, passing north of the 
state Thursday into Friday. Rather breezy or even strong trade winds 
are expected late Thursday into Friday. Latest forecast solutions 
still hint a slight increase in moisture in the island vicinity in 
the mean time. An upper level ridge currently over the area is 
expected to persist, keeping airmass stable. Thus a slight increase 
in low clouds is expected, though hydrological concern from the 
slight increase in moisture will be minimal.

Trades will still likely hold on Saturday, but winds will begin a 
shift to the southeast as another front approaches the area from the 
northwest, pushing a surface ridge near the state. Still expect 
much lighter winds across the islands under the southeasterly winds 
by late Saturday into Sunday, with land breezes and sea breezes 
becoming more widespread. Forecast solutions still indicate the bulk 
of this next front will pass just northeast of the state, though 
moisture from the tail end of this front is expected to spread 
across the area early next week. Models still have slight 
differences in terms of timing of this system and the amount of 
moisture reaching the islands. Regardless, it looks like the weather 
impact from this pending system may not be much, with mainly the 
decreased winds and possible slight increase in clouds and showers.

&&

.AVIATION...
A surface ridge north of the islands will maintain a breezy trade 
wind pattern with relatively dry and stable conditions. VFR 
conditions are expected to prevail. The overnight soundings from 
Hilo and Lihue showed inversions between 6000 and 7000 feet. AIRMET 
Tango continues for mechanical turbulence to the lee of the 
mountains. 

&&

.MARINE...
A ridge of high pressure north of the state will keep moderate to 
strong trade winds in place across the marine area through Friday. 
The trades are then expected to ease over the weekend as a cold 
front passes to our north. A Small Craft Advisory (SCA) remains in 
effect for all Hawaiian waters through Friday for winds, seas or a 
combination of the two.

A moderate northwest swell will produce surf above advisory levels 
through early Thursday morning. A High Surf Advisory (HSA) remains 
in effect for exposed north and west facing shores until then. This 
swell will gradually taper off late Thursday with several small 
reinforcements expected through the weekend. 

Persistent moderate to strong trades will produce rough, elevated 
surf along east facing shores through much of the week. A HSA is in 
effect for east facing shores through at least Wednesday night, but 
will likely need to be extended due to strong trade winds persisting 
through the end of the week. Surf along east facing shores is 
expected to steadily decrease late in the weekend as trades begin to 
decrease.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory until 6 AM HST Thursday for Niihau-Kauai 
Windward-Kauai Leeward-Waianae Coast-Oahu North Shore-Oahu 
Koolau-Olomana-Molokai-Maui Windward West-Maui Central Valley-
Windward Haleakala-South Big Island-Big Island North and East.

Small Craft Advisory until 6 PM HST Friday for all Hawaiian 
water.

&&

$$

DISCUSSION...Hui
AVIATION...MBallard
MARINE...Powell