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000
FXHW60 PHFO 011317
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
317 AM HST Fri Dec 1 2023

.SYNOPSIS...
A kona low west of the islands will bring a continued threat for
heavy rain and flooding along with isolated thunderstorms today.
Conditions will gradually improve over the weekend with stable
trade wind weather expected for the first half of next week.

&&

.DISCUSSION...
Currently at the surface, a kona low is located around 425 miles
west-northwest of Kauai, while a 10 mb high is centered around
1500 miles northeast of Honolulu. A general southeast to south
flow prevails across the islands although convection continues to
disrupt the wind fields early this morning. Infrared satellite
imagery shows mostly cloudy conditions across the state. Radar
imagery shows numerous showers and a few thunderstorms moving
through Oahu, with limited shower activity across the other
islands at the moment. Main short term focus revolves around
heavy rain potential and thunderstorms.

The kona low will gradually break down during the next 24 hours
or so, weakening into a surface trough by daybreak Saturday.
Before it breaks down however, south to southeast boundary layer
flow will continue to pump deeper moisture northward into the
islands with the upper low and jet forcing continuing to provide
forcing for ascent. This will keep the threat for heavy rain and
thunderstorms in the forecast, particularly over the western end
of the state. We will keep the Flood Watch in effect through this
afternoon for all Hawaiian Islands, although the threat for
additional heavy rainfall over the Big Island appears to be
diminishing.

The unstable airmass will linger over the islands through Saturday
with thunderstorms remaining possible across the entire state.
More stable weather will then build into the islands on Sunday as
trade winds begin to return. The trades will strengthen early next
week, with stable trade wind weather prevailing through the middle
of the week. The trades may ease late next week as a new front
approaches from the west.

&&

.AVIATION...
Deep tropical moisture pooling northward over the state due to the
kona low to our west will keep the threat in place for periods of
heavy rainfall and thunderstorms today. A band of showers with
embedded thunderstorms that has developed overnight will likely
continue to impact the western end of the state through much of
the day. Expect periods with IFR and MVFR CIGS/VSBYS in the
heavier showers moving through. Conditions have improved over the
eastern end of the state, which should persist today.

Aside from turbulence and icing associated with any TS that
develops, AIRMET for mid-level turb will continue due to wind
shear in the 100-FL200 layer. Light icing in layered clouds has
also been reported between 120-FL220. AIRMET Sierra for mountain
obscuration will persist over some areas, especially over the
western end of the state where the band of showers is.

&&



.MARINE...
A kona low west-northwest of the Hawaiian Islands will continue
to produce southeast to south winds today with bands of showers,
heavy at times, and thunderstorms developing across the region.
The kona low will weaken this weekend as the ridge builds in north
of the islands. Expect gentle to fresh trade winds spreading
across the region from Saturday to Sunday, strengthening to fresh
to strong trade winds from Monday onward. A Small Craft Advisory
(SCA) remains in effect through today for most coastal waters
surrounding Maui and the Big Island. This SCA will likely be
cancelled by tonight as wind speeds decrease below advisory
thresholds.

The recent small to moderate, medium period northwest (320
degree) swell will gradually decline through Saturday. The next
moderate size, longer period northwest (320 degree) swell will
arrive and begin to fill in Saturday afternoon and evening. This
swell will peak surf to near High Surf Advisory (HSA) heights by
Sunday, then slowly subside Monday. A reinforcing north northwest
(330-340 degree) swell arriving by Monday night and may lift surf
heights well above HSA thresholds and approach High Surf Warning
levels on Tuesday and Wednesday.

Expect the short period wind wave chop to persist along south
facing shores. Small surf continues along south facing shores
with small background south swell pulses next week Monday and
Thursday. Strengthening trades through next week will build surf
heights along east facing shores.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Flood Watch through this afternoon for all Hawaii islands-

Small Craft Advisory until 6 PM HST this evening for Maui County
Windward Waters-Alenuihaha Channel-Big Island Windward Waters-
Big Island Leeward Waters-Big Island Southeast Waters.

&&

$$

DISCUSSION...Jelsema
AVIATION...Gibbs
MARINE...Bohlin