694
FXHW60 PHFO 102000
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
1000 AM HST Sat Aug 10 2024

.SYNOPSIS...
Gentle trades will allow more wind protected area`s local breezes
to dominant the wind regime through the day. Trades will
strengthen to more breezy magnitudes from Sunday through late next
week. Periodic bands of higher moisture moving in from the east
will increase trade wind shower areal coverage. Precipitation
will generally favor better exposed windward areas and mauka
slopes during the overnight hours with a few showers reaching
leeward communities.


&&

.DISCUSSION...
Morning visible satellite imagery shows mainly clear to partly
sunny skies across most lower elevations...partly to mostly cloudy
skies over much of the state`s elevated terrain. A slightly more
active radar in relation to Friday morning. Greater areal coverage
of showers traveling across the windward waters and developing in
the downstream Big Island plume...isolated weak showers sticking
to the smaller island windward-facing slopes. Central Pacific
upper level ridging remains weakened by the influence of troughing
located northwest of the islands. The associated surface cold
front approximately 950 miles northwest of Kauai has caused the
pressure gradient back to the 1029 mb surface high centered 1,700
miles northeast of Oahu to ease a touch these past few days. The
result has been lighter regional trade flow. Localized gentle land
and sea breezes have ruled many communities` diurnal wind patterns
in the absence of this stronger large scale flow. These breezes
will create more efficient cloud growth and shower development
over better wind-protected leeward and interior areas (i.e.,
leeward Big Island). As surface high pressure gradually
strengthens and drifts westward north of the state early next
week, the resultant tighter pressure gradient back toward the
islands will result in a return of more areawide breezy trades.


There are slightly higher probabilities that next week will be a
touch more wet in relation to this past dry week. Weak upper level
troughing begins to develop northeast of the area into mid week.
Lowering heights will lead to slightly higher vertical temperature
inversions and less stable atmospheric profiles. Higher mid-level
moisture advection within stronger trades Sunday and again from
Tuesday onward signals a subtly more wet pattern within a less
stable environment. Remnant moisture from the once was once T.S.
Emilia in the East Pacific may move through Thursday. While
thicker clouds and higher shower frequency will still favor
windward and mauka areas in typical trade wind weather behavior,
occasional showers may make it over the ridgetops and briefly
wetten leeward communities. A drier air mass is expected to follow
for the end of the upcoming work week.


&&

.AVIATION...
Light to moderate trade winds will strenghten slightly tonight
and Sunday, delivering low clouds and periodic brief showers to
windward areas. Developing sea breezes will fuel a few clouds and
showers over leeward coasts and slopes this afternoon, mainly on
the Big Island and Maui. Isolated MVFR CIG can be expected.

No AIRMETs are in effect, and none are anticipated today.


&&

.MARINE...
Building high pressure north of the state will result in the
moderate to locally fresh trade winds today strengthening to
locally strong levels tonight. To account for this uptick in
trades tonight, a Small Craft Advisory will go into effect for the
typically windier waters of Maui county and the Big Island. Winds
may weaken slightly around the middle of the week as a weak
trough moves over the state from the east. Otherwise, little
variation is expected.

A small south swell (14 seconds) will peak today slightly above
the summer average, then slowly decline Sunday and Monday.
Several small south swells may move through the state next week,
keeping small surf along south facing shores.

A tiny pulse from the north northwest will keep tiny ripples
along north facing shores through the rest of the weekend. Small,
below average surf along east facing shores will persist through
the rest of today. As trades increase both upstream and locally,
expect east facing surf to gradually build Sunday into early next
week. A small boost in east facing shore surf is also possible
early next week from former Tropical Cyclone Emilia.


&&

.FIRE WEATHER...
Recent spotty brushfires is a reminder of the recently dry statewide
conditions. Below normal rainfall and higher seasonable temperatures
have resulted in an increase of drought coverage and intensity
since the July 4th holiday. The majority of the islands are under
moderate drought with southern Maui (east of Maalaea Bay) experiencing
extreme drought. One of the fire weather indices such as the
Keetch-Byram Drought Index (KDBI) that helps determine the fire
weather threat is on a consistent rise. Of course, other factors
such as locally dry fuels, high winds and lower relative humidities
all lead to enhancing the fire weather threat within drought.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory from 6 PM this evening to 6 AM HST Tuesday
for Maalaea Bay-Pailolo Channel-Alenuihaha Channel-Big Island
Leeward Waters-Big Island Southeast Waters.


&&

$$


DISCUSSION...Blood
AVIATION...Birchard
MARINE...Vaughan