824 
FXHW60 PHFO 030642
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
842 PM HST Mon Sep 2 2019

.SYNOPSIS... 
Light to moderate trades will continue through Tuesday, then 
increase into the moderate to breezy range Wednesday through the 
second half of the week and upcoming weekend. Clouds and showers 
will favor windward and mountain locations, especially through the
overnight and early morning periods as pockets of higher moisture
move through. The exception will be over the leeward areas of the
Big Island, where afternoon and evening clouds and showers form 
in response to the local sea breeze. 

&&

.DISCUSSION...
The latest surface analysis showed a weak trough northeast of the 
islands and high pressure centered to its north. Despite this trough 
to the northeast, light to moderate trades are holding locally. High 
clouds associated with a large area of showers and storms several 
hundred miles southwest of the area continue to stream over the 
region from west to east due to an upper low to the west. At the 
surface, clouds and showers are focusing over the typical windward 
locations. Rainfall accumulations, however, have remained light over
the past six hours (through 7 PM HST), except for the leeward 
coast of the Big Island over and around Honaunau where heavy 
showers formed and quickly produced up to 1.95 inches (most of 
that falling within a 3-hr period). 

The short-term guidance remains in good agreement and shows the 
trades holding in the light to moderate range through Tuesday as the 
aforementioned surface trough passes to the north. Although drier 
air has moved into the area over the past 24-hrs, the warm 
conditions will continue. High temperatures continue to come in 
higher than predicted each day, especially for Honolulu and Kahului 
(reached 94 and 95 degrees over the weekend). Clouds and showers 
will favor windward and mountain locations, especially through the
overnight and early morning periods. The exception will be over 
the leeward areas of the Big Island, where afternoon and evening 
clouds and showers form in response to the local sea breeze. 

Guidance remains in decent agreement and shows the gradient 
tightening locally as the trough passes to the north and weakens. 
Trades will respond and become breezy through the second half of the 
week. Rising moisture associated with a trough passing far to the 
south is forecast to move through the islands from east to west 
Wednesday through Thursday. Shower coverage will likely respond and 
increase, especially through the overnight and early morning hours 
over windward and mountain locations. 

&&

.AVIATION...
Southwesterly winds aloft will allow for more mid and upper level
clouds to push over the state tonight. However, in the lower
levels, clouds and showers caught in the east northeast trade 
wind flow will be rather limited as drier air infiltrates the
area. Brief MVFR conditions may occur due to mountain obscuration,
but not expecting anything widespread.

No AIRMETs are currently in effect.

&&

.MARINE...
High pressure north of the state will keep moderate trade winds 
in place across the area. Winds and seas are expected to remain 
below Small Craft Advisory levels through Thursday. Trade winds 
are expected to increase to Small Craft Advisory levels over the 
typically windy waters around Maui County and the Big Island 
Friday through the weekend.

A small north-northwest swell is expected to fill in, peak 
Tuesday, then slowly lower Wednesday and Thursday. A series of 
small southerly swells are expected through Thursday, with a 
slightly larger southerly one Friday through Sunday. Easterly 
trade winds will continue to produce short-period, choppy surf 
along east facing shores, with some increase in size expected 
during the middle and latter half of the week.

&&

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

&&

$$


DISCUSSION...Gibbs
AVIATION...Thomas
MARINE...Kinel