Drought in Hawaii, September 1 to 30, 2019

Area Forecast Discussion
National Weather Service Honolulu HI
833 PM HST Sat Aug 31 2019

.SYNOPSIS...
A high pressure system will persist far north of the Hawaiian
Islands with a weakening frontal trough between the high and the
islands. Light to moderate trades will continue through the
weekend. Trade winds will strengthen a bit on Monday as the
frontal trough to the north diminishes. Developing showers will
favor windward and mauka areas in the overnight to early morning
hours.

&&

.DISCUSSION...
Satellite imagery shows bands of clouds passing through the region
tonight. Water vapor imagery continues to show two upper lows far
north and west of the state within a narrow upper trough axis.
Local radar imagery this evening shows scattered showers
developing upstream of all islands. These showers will
periodically drift into the windward and mountain sections of
each island on light easterly trade winds through the early
morning hours.

A record high temperature of 95 degrees Fahrenheit was reported
at the airport in Honolulu today. A preliminary review of our
climate records show this temperature broke several records for
Honolulu, including a previous August monthly high temperature
record of 94 degrees set on August 29th of this year, and this
report tied the all time high temperature record of 95 degrees set
in Honolulu on September 19th 1994.

A high pressure system far north of the Hawaiian Islands will
continue to produce lighter than normal trade winds through much
of next week. Above normal temperatures are also forecast due to
lighter winds and warmer than normal ocean temperatures. A slight
increase in trade wind speeds remains in the forecast for Labor
Day. However, sea breezes will continue to form along the more
sheltered western and southwestern slopes of each island each day.
Clouds will favor windward mountain areas in the overnight and
early morning hours, trending towards interior sections of each
island in the afternoon hours. Isolated to scattered showers
remain in the forecast for most areas. Interior sections of Maui
and the Big Island may see more enhanced showers and a few
thunderstorms on Sunday due to the stronger surface heating. Only
subtle changes to the day to day weather conditions are expected
through Tuesday.

In the longer range forecast from Wednesday onward we see the
upper low north of the state drifting closer to the islands on
Wednesday with a low level trough spreading additional moisture
and instability across the region from east to west. Expect
enhanced showers on Wednesday across the Big Island and Maui.
Increased clouds and enhanced showers will spread westward to the
rest of the state from Wednesday night into Thursday. The high
pressure ridge north of the islands builds back in on Friday with
more typical moderate to breezy trade wind weather lasting into
next weekend.

&&

.AVIATION...
Similar to the past 24-hours, scattered high clouds continue to
stream over the state from the tropics. Meanwhile, enhanced low
level moisture edges toward the islands from the east northeast,
caught in the trade wind flow. Expect showers tonight to mainly be
limited it to the windward slopes, coasts, and adjacent waters.
Brief MVFR conditions may develop due to mountain obscuration from
these low clouds and showers.

No AIRMETs are currently in effect.

&&

.MARINE...
High pressure far north of the islands will drive moderate to
fresh trades across the area through at least the middle of next
week, with possible strengthening in the wind speeds by the end of
the week. Surf along east facing shores should remain small until
then.

The current southwest swell is on its way down tonight with only
background swells expected for Sunday. Exposed southeast facing
shores may see a slight increase in surf Monday night through the
middle of next week as a small southeast swell moves through. A
series of south-southwest swell will be possible during the
second half of next week and into the weekend.

A small to moderate north swell will continue through the rest of
the weekend with the peak expected on Sunday. A slightly larger
north-northwest swell will generate surf along north and west
facing shores beginning Tuesday.

&&

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

&&

DISCUSSION...Bohlin
AVIATION...JT
MARINE...Kino