Area Forecast Discussion
Issued by NWS Honolulu, HI

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000
FXHW60 PHFO 220140
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
340 PM HST Thu Mar 21 2024

.SYNOPSIS...

Breezy northeast trade winds will persist into Friday before
becoming more easterly this weekend through early next week.
Drier air will fill in over the weekend providing limited clouds
and showers along windward and mauka locations.

&&

.DISCUSSION...

Latest CIMSS precipitable water vapor imagery shows below average
values centered over Oahu and Molokai. Visible satellite imagery
shows clearer skies in this area with clouds focused along
windward and mauka areas. Radar and latest rainfall totals show
that rainfall has been focused along these windward and mauka
areas, especially for Maui and the Big Island but rainfall totals
remain on the lighter side. Rainfall totals have thus been
adjusted downward for windward areas over Maui County late this
afternoon and early evening as this area of drier air meanders
near the central islands.

This afternoon ASCAT pass shows a band of stronger winds north of
Kauai. Guidance remains on track with these stronger winds
shifting southward over the state tonight into Friday, as a band
of moistures rides ahead. This will translate to a slight increase
in clouds and showers for Kauai and Oahu tonight and the rest of
the state Friday.

Breezy northeast trade winds will veer more easterly this weekend
as a gradually strengthening high pressure north of the state tracks
eastward. Chances of precipitation has been damped down over the
weekend as the airmass becomes drier than normal. Any clouds and
showers that do form will be limited to windward and mauka areas.
Guidance indicates a trend towards an increase in moisture early
next week, as an area of enhance precipitable water values moves
in from the south to the north, raising values to around 1.5
inches across the state by Tuesday. In addition a mid to upper
level disturbance building over the state could provide a more
pronounced uptick in shower coverage over windward areas, while
breezy trade winds persist.

&&

.AVIATION...
Moderate to locally breezy trade wind flow will prevail, and
AIRMET TANGO is posted for low-level turbulence. Broken low
clouds and showers over windward Big Island will likely persist
into Friday, and AIRMET SIERRA is posted for mountain obscuration
as periods of MVFR VIS/CIG are expected. Isolated showers and VFR
will prevail in the short term elsewhere, but an area of increased
showery low clouds will likely move over the smaller islands from
the NE later tonight and Friday, bringing periods of MVFR
conditions to windward areas.


&&

.MARINE...
Surface high pressure north of the state will slowly strengthen
and drift east through the weekend resulting in a gradual increase
in winds. The Small Craft Advisory (SCA) is in effect for the
typically windier waters near Maui County and the Big Island
through Friday, with the potential for additional zones to be
included as the stronger trades become more widespread Friday
into Saturday.

The current moderate northwest (310-320 degree) swell will
gradually decline through Friday. A new reinforcement small to
moderate long period northwest (310-320 degree) swell, is expected
to arrive late Friday with another slightly larger reinforcement
from the same direction Sunday night and Monday. This late weekend
swell will likely result High Surf Advisory level criteria for
exposed north and west facing shores.

Surf along south facing shores will return to background levels
for the next several days. Short period trade wind swell will be
below seasonal average through today and will likely pick up
Friday through the weekend as trade winds increase.


&&

.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...Almanza
AVIATION...Birchard
MARINE...Foster


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