059
FXHW60 PHFO 291957
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
957 AM HST Sat Jun 29 2024

.SYNOPSIS...
Moderate trade winds will prevail through the weekend, strengthening
somewhat early next week, then remaining breezy. Clouds and showers
will favor windward areas, with the potential for increased shower
coverage and intensity this weekend due to a nearby upper-level low.
The low will also bring the potential for isolated thunderstorms
over the interior Big Island this afternoon, and near Kauai through
Sunday. Stable trade wind weather will prevail next week, with just
a few brief windward showers.

&&

.DISCUSSION...
Morning soundings show the island atmosphere is moderately unstable
due to the presence of a well-developed low aloft that is centered
about 200 miles NE of Oahu. A weak inversion is noted near 8 kft in
the PHLI sounding, with moderate instability aloft, with a weaker
inversion/greater instability aloft noted in the PHTO sounding.
However, visible satellite images show very little in the way of low-
level moisture arriving from the E on a gentle to moderate trade
wind flow. Meanwhile, heavy showers have been occurring in the cloud
plumes W of the islands through the night, where moisture
convergence is maximized near the axis of the trough aloft.

The forecast anticipates that the trade-wind-supporting ridge N of
the islands will remain on the weaker side through tomorrow, then
strengthen early next week, with trade winds speeds following suit.
Typical summertime breezy trade winds will prevail during the
upcoming week.

The low aloft will move generally W through the weekend, passing N
of Kauai on Sunday, then lift N Monday and Tuesday as a strong mid-
level ridge builds in from the E. This stabilizing ridge will
persist through the week. Until then, the passage of the low will
bring the potential for isolated heavy showers and/or a
thunderstorm. Limited moisture will keep coverage reduced, but the
interior of the Big Island appears most likely the this afternoon
(and maybe again tomorrow), and near/over Kauai through Sunday.

&&

.AVIATION...
High pressure north of the islands will maintain moderate trades
through the weekend as an upper-level low northeast of the state
drifts west. Showers and low clouds will affect mainly windward and
mauka areas. The upper-level low will help to enhance shower
coverage this weekend, especially during the overnight and early
morning hours. Expect brief periods of MVFR conditions under heavier
showers. Otherwise, VFR conditions should prevail.

No AIRMETs are currently in effect. However, AIRMET Sierra may
become necessary over portions of the state as shower coverage
increases.

&&

.MARINE...
High pressure north of the state will maintain moderate to fresh
trade winds through the weekend. The trades are expected to
strengthen back to fresh and strong levels early next week, and a
Small Craft Advisory will likely be required for the typically windy
waters around Maui and the Big Island by Monday. An upper level low
passing nearby will bring a slight chance of thunderstorms around
Kauai tonight and Sunday.

A series of south swells will keep south shore surf near the
summertime average through Saturday. Surf will lower below normal
levels much of next week. A small background south swell could give
south shore surf a slight bump around the middle of next week.

Typical mostly flat summertime conditions will continue along north
facing shores through next week.

East shore surf will remain well below normal through the weekend,
then trend up and closer to seasonal levels next week as the trades
strengthen over and upstream of the islands.

Water levels running roughly 0.5 ft higher than normal around the
Big Island combined with the new moon tides could cause minor
coastal flooding issues between July 3rd and July 6th. Our last full
moon, we received reports of some coastal flooding during high tide
on Coconut Island and in Puhi Bay. For the other islands, water
levels are running just a touch above normal.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...Birchard
AVIATION...Ahue
MARINE...Kino