723
FXHW60 PHFO 291321
AFDHFO

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

.SYNOPSIS...
A high pressure ridge will remain in place north of Hawaii into
next week, producing moderate trade winds through Sunday, and
then strengthening into the moderate to breezy range from Monday
onward. Passing showers are expected to mainly affect windward and
mountain areas, favoring the overnight to early morning hours. An
upper level low will continue to drift from east to west over the
islands this weekend, likely increasing shower activity as it
passes through the state. Isolated thunderstorms are possible over
the interior Big Island this afternoon, and near Kauai through
Sunday.

&&

.DISCUSSION...
An upper level low shown on satellite water vapor imagery around
400 miles northeast of Hilo, Hawaii will continue to drift west
through the weekend. This system continues to enhance showers and
produce a few thunderstorms over the coastal waters west of the
Big Island and over portions of the Alenuihaha Channel this
morning. This upper low will enhance showers over each island
through Sunday, then weaken and drift northward away from the
state on Monday. Isolated thunderstorms are possible this
afternoon over the interior sections of the Big Island, and then
near Kauai tonight through Sunday.

The subtropical ridge will remain in place north of the state into
much of next week keeping easterly trade winds in the forecast for
most days. The upper low will continue moving westward across the
state of Hawaii over the next few days. A weak low level trough
associated with the upper low will keep the pressure gradient on
the weaker side, keeping trade winds at moderate levels through
Sunday. By Monday expect the ridge to build in over the islands as
the upper low departs the pattern, with trade winds increasing
into the moderate to breezy range through much of next week. A
stronger high pressure ridge will also produce more stable
conditions with increasing subsidence over the state next week
with decreasing shower trends. Trade wind thermal inversion
heights will range from 5,000 to 6,500 feet keeping brief passing
showers in the forecast over windward and mountain areas,
trending higher in the overnight to early morning hours.

&&

.AVIATION...
Moderate trades are expected to continue across the island chain
through the weekend. SHRA and low cigs embedded in the trades
will bring brief periods of MVFR conds over windward and mauka
locations. Otherwise, VFR conditions should prevail.

An upper-level low is forecast to move over the islands this
weekend. This will likely cause increased SHRA coverage and
require AIRMET Sierra periodically throughout the weekend,
especially during the overnight and early morning hours.

&&

.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.

&&

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

&&

$$

DISCUSSION...Bohlin
AVIATION...SMW
MARINE...Jelsema