Wildfire in Hawaii, September 4 to 5, 2019

Area Forecast Discussion
National Weather Service Honolulu HI
957 AM HST Wed Sep 4 2019

.SYNOPSIS...
Increasing trade winds today will remain moderate to breezy
through the upcoming weekend. Clouds and showers will favor
windward and mountain locations, especially through the overnight
and early morning periods. Additional clouds and showers will be
found over the leeward areas of the Big Island during the
afternoon and evening hours.

&&

.DISCUSSION...
No major changes to the forecast this morning. Have boosted PoPs
and QPF over the east and south side of the Big Island this
morning in response to the showers moving in at this time. Showers
should be on the decline this afternoon.

A weakening surface trough north of Kauai continues to weaken as
it moves to the west. As this feature moves to the west and
weakens, expect the trade winds to be on the increase today. The
moderate to breezy trades are then expected to stick around the
islands into the upcoming weekend with ridge to the north of the
islands.

A weak trough south of the islands is helping to bring increased
clouds and showers to the southern end of the state. As this
trough weakens and moves to the west, the clouds and showers will
move to the west of the islands and dissipate.

Otherwise expect trade winds to focus clouds and showers over the
windward and mauka areas of all the islands, with more showers
overnight and during the early morning hours. Afternoon clouds and
showers are possible over leeward areas of the Big Island. As
trade winds strengthen, some of the clouds and showers over the
smaller islands will find their way to leeward areas.

Tropical Depression Twelve-E has formed near 140W, and the first
bulletin on the system was issued by the National Hurricane Center
at 5am. The system is currently over 1000 miles southeast of the
Big Island. The Central Pacific Hurricane Center will begin
issuing advisories on the system at 11am. Exact details on the
impacts this system would have on the Hawaiian Islands continue
to be uncertain this far out. The system is currently expected to
pass south of the islands and could bring an increase in moisture
to the islands late this weekend and into next week.

&&

.AVIATION...
Moderate to locally breezy trade winds are expected across the
region today. A trough passing south of the state will bring
enhanced low clouds and numerous showers to the eastern slopes of
the Big Island throughout the day. Scattered showers and isolated
thunderstorms are possible over the Big Island western slopes and
portions of the interior by afternoon. Elsewhere, scattered
windward showers are expected, though VFR conditions should
prevail.

AIRMET Sierra is in effect for TEMPO mountain obscuration along
the eastern slopes of the Big Island. This AIRMET will likely
continue through the afternoon hours and coverage may need to be
extended to include the leeward slopes as well.

&&

.MARINE...
High pressure north of the state has been strengthening, and trade
winds are on the increase across the area. A Small Craft Advisory
is in effect for the typically windy waters around Maui County
and the Big Island, and will likely be extended through the
weekend.

A small north-northwest swell is expected to slowly lower through
Thursday. A series of small southerly swells are expected through
Thursday as well, with a slightly larger reinforcement Friday
through Sunday. This last southerly swell may be enough to bring
advisory level surf to south facing shores Sunday and Monday. The
trades will continue to produce short-period, choppy surf along
east facing shores, with some increase in size expected by the end
of this week.

&&

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

&&

DISCUSSION...M Ballard
AVIATION...Dye
MARINE...Morrison