High Surf in Hawaii, June 2 to 4, 2020

Area Forecast Discussion
National Weather Service Honolulu HI
317 AM HST Tue Jun 2 2020

.SYNOPSIS...
Trade winds will trend up later today through Wednesday as the
ridge strengthens north of the state. Clouds and showers will
favor windward and mountain areas each day, especially through the
overnight and early morning periods as pockets of moisture move
through. Drier air moving in from east to west Friday will limit
shower coverage through the weekend.

&&

.DISCUSSION...
Latest surface analysis and satellite imagery showed a ridge
anchored north of the islands and a cloud band associated with an
old front located a few hundred miles to the northeast. Satellite-
estimated precipitable water (PW) imagery depicted a decent-sized
area of higher than normal moisture in the area for this time of
year with values ranging from 1.7 to 1.9 inches. A combination of
this low-level moisture and moderate trade winds will support
scattered shower coverage over windward and mountain locations
today. Although mostly dry conditions will prevail over leeward
locations, a few brief showers spilling over can't be ruled out.
Rainfall accumulations should remain light.

Guidance remains in decent agreement and shows the subtropical ridge
strengthening north of the state later today through midweek,
which will translate to a return of moderate to breezy trade winds
statewide. Despite the aforementioned moisture lingering in the
area fueling windward showers each day, middle- to upper-level
ridging and dry air will limit accumulations. Guidance supports
drier air moving into the area late Thursday through Friday with
PWs dipping back to around an inch and dewpoints lowering from
near 70 degrees to the mid 60s - which should hold through the
weekend. Although confidence lowers significantly this far out in
time, trade winds may trend back down Sunday through early next
week as a weakness develops within the subtropical ridge in
response to lowering upper heights and a front passing to the
north.

&&

.AVIATION...
Trade winds will be in the light to moderate range as a high
pressure area remains far northeast of the islands. Remnant
showery low clouds from a dissipated front, with accompanying MVFR
ceilings and/or visibilities, will mainly affect windward and
mauka sections around the island chain through tonight.

No AIRMETs are currently in effect.

&&

.MARINE...
Trade winds will remain at moderate to locally fresh strength
today as surface high pressure far north of the state lifts away.
Trade winds will gradually strengthen to fresh to locally strong
levels late today and Wednesday as a surface ridge builds north
of the islands. A Small Craft Advisory is now in effect for
typically windy waters around the Big Island and Maui.

South shore surf will rise today as long period forerunners of
a south-southwest swell arrive. Advisory level surf is expected
as the swell peaks later today and Wednesday. This swell will
decline Thursday and Friday and may be reinforced by a smaller
south-southwest swell this weekend.

No significant sources of swell are noted from the north and
east. The current, small north swell will be replaced by a small
northwest swell today to Thursday. With trade winds suppressed
over and upwind of the islands, east shore surf is well below June
average. Look for an increase to near to just below June normal
Thursday through the weekend.

&&

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

Small Craft Advisory until 6 PM HST Thursday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big
Island Southeast Waters.

&&

DISCUSSION...Gibbs
AVIATION...Kinel
MARINE...Powell