Drought in Hawaii, May 1 to 31, 2019

Area Forecast Discussion
National Weather Service Honolulu HI
840 PM HST Tue Apr 30 2019

.SYNOPSIS...
A trade wind weather pattern will persist through Thursday as
high pressure passes by north of the area. Clouds and passing
showers will favor windward and mauka areas. A front will approach
the area Friday and pass across the area Friday night through
Saturday night. Shower activity will increase ahead and along the
frontal boundary. North to northwest winds will fill in behind the
front with a drier weather pattern setting up for early next
week.

&&

.DISCUSSION...
Trade winds prevail this evening as high pressure builds to our
north. Moisture associated with an old front provides passing
showers over Kauai and windward Oahu, with isolated windward and
mauka showers seen elsewhere. The southern end of an upper trough
is noted in water vapor imagery just east of the Big Island. This
made the airmass a bit unstable over the Big Island this
afternoon, resulting in some deeper convection. This activity has
since dissipated.

High pressure will pass north of the area Wednesday and Thursday,
keeping the islands in a typical trade wind weather pattern.
Passing showers will tend to favor windward and mauka areas with
most leeward locations remaining dry.

On Friday, a strong upper trough, along with its associated
frontal boundary, will approach the area from the northwest.
Winds will become light and generally out of the south out ahead
of the front. Low level convergence ahead of the front will
likely trigger shower development. Some of these showers may be
locally heavy. Models indicate the front will pass across the
area from west to east Friday night through Saturday night. The
front will be accompanied by a period of showers. Northwest winds
will fill in behind the front, but bands of moisture embedded in
the northwest flow may provide for some passing showers at times
on Sunday, especially over north facing slopes. Drier weather is
expected early next week, but we will remain in northerly flow
due to low pressure lingering north of the area.

&&

.AVIATION...
As a high pressure center passes by north of the islands, trade
winds will be in the light to moderate range, with locally
breezy periods, through Wednesday. VFR will predominate. Isolated
areas of MVFR conditions in lower ceilings and showers will be
mainly confined to windward and mauka sections across the state.

No AIRMETs are currently in effect.

&&

.MARINE...
Moderate to locally strong trades will continue for another day before
it collapes and turn southerly Thursday night as a trough and
front approaches the islands from the west. A Small Craft Advisory
(SCA) is in effect to until 6 am HST Thursday for waters around
Maui County and waters south of the Big Island.

Inclement weather is expected between Thursday night and Sunday. The
weather will first be associated with a surface trough and front
pushing through the island chain between Friday and Saturday. A
surface low follows in, cutting across the northern offshore waters
on Sunday and Sunday night. The passing of the front will usher in
a light to moderate northwest wind flow to the area.

The current northwest swell will continue to decline through
Wednesday with a small to moderate size reinforcement arriving late
Wednesday, peak Thursday, followed by a slowly decline into
Saturday. A new short- period, north- northwest swell, generated
by the expected surface low, arrives early Sunday, peak Sunday
night, then gradually lower through early next week. Surf will
likely remain small along most east facing shores into this
weekend, despite a small bump from breezy trades the next couple
of days. A series of long-period southwest swells is forecast to
reach the islands between Friday and Sunday. Otherwise, surf will
remain small through the period.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 AM HST Thursday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Southeast Waters.

&&

DISCUSSION...Powell
AVIATION...Kinel
MARINE...Lau