Drought in Hawaii, May 28 to 31, 2019

Area Forecast Discussion
National Weather Service Honolulu HI
809 PM HST Mon May 27 2019

.SYNOPSIS...
Light east to southeast winds will continue through midweek due
to a stalled frontal boundary northwest of the state. Overnight
land breezes and daytime sea breezes will prevail each day.
Daytime heating combined with the afternoon sea breezes will
translate to the best cloud and shower coverage through the
afternoon periods, mostly over interior and leeward portions of
the islands. A return of moderate to breezy trades is anticipated
through the second half of the week and upcoming weekend as the
ridge strengthens to the north and the lingering front lifts
northward and diminishes. Clouds and shower coverage will
transition back to the typical windward and mauka areas.

&&

.DISCUSSION...
The latest analysis showed a lingering frontal boundary stalled
northwest of the islands and a weak ridge positioned to the north.
The low-level flow has weakened and shifted out of the east-
southeast over the islands, which has resulted in localized sea
breezes becoming established today. Despite the mostly stable
conditions and plenty of mid-level dry air in place (1.05 to 1.12
PWs), a few moderate to locally heavy showers have managed to
develop over interior and leeward sections through the late
afternoon and early evening hours. These showers should be brief
with minimal accumulations. As this activity diminishes through the
evening hours with the loss of daytime heating, mostly quiet
conditions should prevail overnight with land breezes and clearing
expected.

The latest short-term guidance remains in decent agreement through
Wednesday and shows the weakness within the ridge to the north
holding in place due to the aforementioned frontal boundary
lingering to the northwest. Overnight land breezes and daytime sea
breezes will result. Similar to this afternoon, clouds and showers
will favor interior and leeward sections through the afternoon
periods. Although a few brief heavy afternoon/early evening
downpours can't be ruled out, plenty of middle- to upper-level
dry air and stability should limit rainfall duration/accumulations.
Clearing will be expected through the overnight periods as the
land breeze becomes established. The exception will be over
windward sections of the eastern half of the state where the
background east-southeast flow may prove to be enough to generate
a few windward showers overnight into the early morning hours,
especially as pockets of moisture move through.

A return of moderate to breezy trades is expected Thursday through
Friday as the ridge strengthens to the north, which will continue
through the upcoming weekend. Clouds and shower coverage will
transition back to the typical windward and mauka areas, with very
little making it into leeward areas.

&&

.AVIATION...
The Hawaiian Islands remain along the edge of a high pressure
ridge with a stalled surface cold front roughly 300 miles
northwest of Kauai. A light east-southeast background wind flow
will interact with overnight off-shore land breezes and daytime
on-shore sea breezes through Wednesday. Wind directions will be
more variable than normal during the afternoon hours.

Cloud ceilings will form in the afternoon hours with clearing
conditions a few hours after sunset. Isolated to scattered showers
will develop over each island favoring mountain areas, interior
sections, and along sea breeze convergence zones. Mostly VFR
conditions are forecast for the next 24 hours.

No AIRMETs in effect and none are expected.

&&

.MARINE...
Trade winds associated with a surface ridge north of the islands
will trend down into the light to moderate category through
Wednesday. The trades are forecast to gradually strengthen during
the second half of this week as surface high pressure builds
north of the region.

The long-period south-southwest swell continues to gradually
decline, but it remains elevated early this evening according to
the coastal buoy observations. Therefore, a High Surf Advisory
(HSA) remains in effect through early Tuesday morning. We will
monitor the observations overnight in case the swell unexpectedly
remains elevated, and the HSA needs to be extended during the
daytime hours on Tuesday.

As the current south-southwest swell continues to subside, a new
long-period south swell, which is expected to be slightly
smaller, will begin to fill in on Tuesday, and persist through
mid-week. Another small reinforcing south swell is expected to
spread across the island chain from Thursday through Friday.

The current late season small northwest swell will continue to
gradually lower through Tuesday and Wednesday. A new northwest
swell may arrive early Thursday, while keeping the bump in surf
heights along most north and west facing shores of the smaller
islands. This swell will gradually subside from Friday into next
weekend.

Surf along east facing shores will continue to lower through the
first half of this week due to the weaker trade winds. An upward
trend in surf along east facing shores is expected during the
second half of the week as the trades strengthen.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory until 6 AM HST Tuesday for Niihau-Kauai
Windward-Kauai Leeward-Oahu South Shore-Waianae Coast-Molokai
Leeward-Lanai Makai-Kahoolawe-Maui Leeward West-Maui Central
Valley-Leeward Haleakala-Kona-South Big Island-Big Island North
and East-Kohala.

&&

DISCUSSION...Gibbs
AVIATION...Bohlin
MARINE...Houston