368
FXHW60 PHFO 300158
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
358 PM HST Sat Jun 29 2024

.SYNOPSIS...
Gentle to moderate trade winds will prevail through the weekend.
Trades will strengthen Monday, then remain breezy through the
upcoming week. Clouds and showers will generally favor windward
areas, but some leeward areas will again see some showers on Sunday
afternoon. There remains the potential for an isolated heavy
downpour through Sunday due to a nearby upper-level low. Stable
trade wind weather will prevail next week, with just a few brief
windward showers.

&&

.DISCUSSION...
Afternoon soundings show the island atmosphere remains 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, while
the inversion is absent from the PHTO sounding, with greater
instability aloft. Trade wind speeds are below seasonal norms, and
have been sufficiently light to allow sea breeze circulations along
leeward coasts to move inland, driving the formation of some showery
low clouds. The greatest amount of cloud and shower coverage has
been over leeward Big Island (where 1-2" of rain fell in localized
areas), and interior and leeward portions of Oahu received some
rainfall this afternoon as well. Recent radar imagery shows showers
developing over leeward Haleakala as well. Meanwhile, 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.

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.
With winds remaining light and the atmosphere remaining unstable, an
afternoon similar to today`s is expected tomorrow. However, since
thunderstorms have not been observed the last couple of days, they
have been removed from the forecast. Thereafter, 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 an isolated heavy shower. Limited moisture
will keep coverage reduced, but the interior of the Big Island
appears most likely Sunday afternoon, 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 continues to drift west.
Leeward sea breezes will continue through this evening. Showers and
low clouds will return to windward and mauka areas tonight. VFR
should prevail, with brief periods of MVFR under heavier showers.

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.

As the current south swell fades away on Sunday, a series of small
south-southwest and southeast swells will keep south facing shores
from going flat this upcoming week. Otherwise, no significant south
swells are expected.

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
flooding issues between July 3rd and July 6th. Our last full moon,
we did receive reports of some areas of the coastline becoming
inundated with the high tide such as Coconut Island and 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