934
FXHW60 PHFO 131326
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
326 AM HST Sat Jul 13 2024

.SYNOPSIS...
A large area of high pressure generally north of the Hawaiian
Islands will hold the next several days. This will maintain the
ongoing typically dry summertime trade wind pattern. Thicker more
areal coverage clouds and more frequent showers will continue to
favor more windward exposures and mauka zones. The next decent
chance of more island-wide rain may be early next week in response
to a vicinity upper level disturbance northeast of the state.


&&

.DISCUSSION...
There is little variance in forecast philosophy under this near
static Central Pacific synoptic pattern. Summertime dry trades
persist as a pair of highs centered northwest and northeast of
the islands drive primarily fresh to locally strong easterlies.
Relatively lower inversion 5-6k foot heights will result in a
more shallow boundary layer, in tandem with dry mid to upper
level moisture (< 30% RH) advecting in across the chain, nearly
guarantees a stable enough island environment that will generally
support windward and mauka cloudier skies and occasional showers.
The usual suspect caveats of cloudier, slightly more wet afternoon
Kona and Ka`u slope conditions with infrequent leeward sprinkles
and partly cloudy skies riding over local area ridge tops still
apply.

The development of an upper level disturbance forming in the
middle of northern ridging will be the impetus of gradually
weakening trades. The reflection of lowering surface pressures,
along with the proximity of a subtropical jet, may work in favor
of increasing more areawide pockets of better organized early week
shower activity. The main question marks to increased shower
activity will be whether or not there will 1) be ample column
moisture within a deepened, marginally-destabilized boundary
layer and 2) the location of the upper disturbance in relation to
the islands. The wettest period is shaping up to be on Days 6 & 7
(next Thursday and Friday). This is the time at which inversions
are slightly higher (closer to 6.5k ft), lapse rates are the
greatest (5 to 6 deg C in lowest 3 km) and moisture is highest (>
80% RH). These three elements best come in-line over Big Island
and Maui Counties in closing out the traditional work week.


&&

.AVIATION...
Breezy to locally windy trades will continue for the next few
days. SHRA and low cigs will favor windward and mauka locations.
Brief MVFR conds are possible in any SHRA. VFR conds should
generally prevail.

AIRMET Sierra for mtn obsc remains in effect for N thru SE
sections of Kauai, Oahu, Molokai, Maui and the Big Island.

AIRMET Tango for mod low-level turb lee of island terrain will
remain in effect for the next several days due to the strong
trades.


&&

.MARINE...
A strong high pressure ridge north of the Hawaiian Islands will
continue to keep fresh to strong trade winds in the forecast
through the weekend and into much of next week. Typical windier
channel areas will see wind speeds near gale forecast at times
with seas approaching 10 foot advisory levels. A Small Craft
Advisory (SCA) remains in effect for all Hawaiian Coastal Waters
through early Sunday morning. A subtle decrease in the trade
winds are forecast by early next week. The SCA winds will linger
in more than just the typical windier waters for most of next
week.

A more significant long period south swell will fill in late
tonight, reaching High Surf Advisory (HSA) levels for south
facing shores on Sunday and Monday. West facing shores will see a
decent south swell wrap, boosting surf heights as well, with the
Big Island west facing shores likely reaching HSA levels on
Sunday. A gradual downward trend is expected Tuesday through
midweek.

Due to the strong trade winds upstream of the state, surf along
east facing shores will remain rough and choppy through early
next week. A downward trend is possible around midweek as the
upstream fetch weakens and the local trades begin to ease.


&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 AM HST Sunday for all Hawaiian
waters-


&&

$$


DISCUSSION...Blood
AVIATION...Walsh
MARINE...Bohlin