FXHW60 PHFO 031338
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
338 AM HST Fri May 3 2024

.SYNOPSIS...
The high pressure center far north of the Hawaiian Islands will
build today producing breezy trade winds across the region for the
next several days. An upper level disturbance will enhance
passing showers in the forecast into early next week, favoring
windward and mountain areas in the overnight to early morning
hours. A few of the stronger showers will drift into leeward
areas. Long range guidance shows an old frontal band moving into
the islands from the northeast by early next week Wednesday. This
cloud band may bring another brief round of wet weather to all
islands from Wednesday morning into Thursday.

&&

.DISCUSSION...
Radar imagery this morning shows a fairly wet weather pattern over
most island windward and mountain areas. These enhanced shower
trends will tapper off a bit by mid morning to afternoon, then a
return to more showers later this evening. Satellite water vapor
imagery continues to track an unstable upper low northwest of
Kauai with an upper level trough lingering over the state. A
subtropical jet stream is also evident near the islands. Upper
level divergent forcing will continue to keep enhanced showers in
the forecast for the next several days.

Two high pressure systems in the Central Pacific far north of the
Hawaiian Islands will consolidate into one high center today.
This high center will build slightly just north of the Hawaiian
Islands and increase trade winds into breezy range into Monday.
By Monday afternoon the high center begins to drift eastward away
from the islands with a frontal trough moving into the Central
Pacific basin. This change in large scale pressure patterns north
of the islands will decrease trade wind speeds back to more
moderate levels from Monday night onward.

Expect continued enhanced showers across the state as the unstable
upper level disturbance slowly drifts eastward across the island
chain. Most of the rainfall amounts will favor windward and
mountain areas as breezy trade winds build clouds up and over the
windward mountain slopes. Down sloping trade wind flow over the
leeward sides of island mountain ranges will tend to decrease
shower activity for leeward areas of each island. Shower trends
will tend to increase during our typical diurnal rainfall maximum
in the overnight to early morning hours.

In the extended forecast we continue to see a long band of
unsettled shallow clouds, remnants of an old Eastern Pacific cold
front, drifts into the islands on the moderate trade winds from
Wednesday morning into Thursday. This cloud band may produce wet
weather over all islands for an 18 to 24 hour time period. The
highest rainfall amounts will tend to favor windward areas,
however many leeward sites may also see measurable rainfall totals
with this next system. This fairly shallow cloud band will likely not
be deep enough to produce heavy rainfall, rather more beneficial
rain is forecast for all islands. Rainfall chances were increased
for the Wednesday into Thursday time period.

&&

.AVIATION...
Moderate to breezy E trades will continue to strengthen through
today as high pressure builds in from the NE. A moisture plume
riding the trades should bring in SHRA and MVFR conds to windward
and mauka locations. While a few SHRA and lowering cigs/vsbys
could reach leeward side, they look to be brief even with a slight
increase in coverage. VFR conds should prevail.

AIRMET Sierra is in effect for mtn obsc for windward and mauka
portions of the island chain.

AIRMET Tango is in effect for mod turb below 080 downwind of
island terrain.

AMD NOT SKED in for Midway due to missing wind speed and
direction

&&

.MARINE...
Latest ASCAT shows fresh to locally strong winds have arrived as
a high pressure builds far north of the state. These stronger
trades will continue through the weekend and drop a notch or two
early next week as the high moves far northeast of the state. The
Small Craft Advisory (SCA) for typical windy waters around Maui
and the Big Island has been expanded to all waters through early
Monday morning. Some area may drop out earlier as winds begin to
ease due to the high shifting northeast.

Tiny surf will persist along north and west facing shores
through much of today. Forerunners of a long period northwest
swell is expected to fill in this afternoon and peak Saturday,
bringing small surf along north and west facing shores. Another
small, long period northwest swell will fill in late Sunday,
maintaining small surf along north and west facing shores into
early next week. Small background south swells will continue into
Saturday, providing tiny surf for south facing shores. Forerunners
of a small, long period south swell may arrive Saturday afternoon
with a slow onset through Sunday providing a boost in surf along
south facing shores into early next week. Rough and choppy surf
along east facing shores will bump up a notch Saturday and hold
hold into early next week as strong trades hold.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 AM HST Monday for all Hawaiian
waters-

&&

$$

DISCUSSION...Bohlin
AVIATION...SMW
MARINE...Almanza