993
FXHW60 PHFO 271942
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
942 AM HST Thu Jun 27 2024

.SYNOPSIS...
Stable conditions and breezy to locally windy trade winds will
continue today. Light showers will generally focus along windward
and mauka areas. An upper level low will approach the islands on
Friday and pass north of the state this weekend. This will
destabilize the island atmosphere, increasing shower activity and
introducing isolated thunderstorm chances for portions of the
region.

&&

.DISCUSSION...
Breezy to locally strong easterly trade winds continue to prevail
across the islands today as high pressure remains centered far
north-northeast of the state. Latest radar and satellite imagery
this morning shows mostly dry conditions, though a few light
showers are continuing to move into windward and mauka areas.
Rainfall amounts have been relatively light, with windward and
central Oahu receiving the most rainfall this morning. For the
rest of today, expect continued breezy to locally strong trades
with isolated to scattered light showers favoring windward and
mountain locations. Leeward areas will remain mostly dry, with the
exception of the Kona slopes of the Big Island where afternoon
cloud buildups and a few showers will be possible.

The high pressure to our north will subtly weaken tonight, which
will relax the local pressure gradient a bit, easing winds for
Friday into the weekend. Impulses of moisture embedded in the
trade wind flow will continue to favor windward and mauka areas,
though rainfall accumulation will be limited for most locations
through Friday. However, guidance remains consistent that a low
aloft will approach the region from the east beginning on Friday.
This will begin to destabilize the island atmosphere. It is
possible that isolated thunderstorms could develop over the Big
Island slopes Friday afternoon, fueled by daytime heating,
topographic effects, and an increasingly unstable environment.

The low aloft will continue moving towards the main Hawaiian
Islands this weekend, enhancing trade wind showers and introducing
the possibility of isolated thunderstorms across the far western
end of the state closer to the low. Additionally, isolated
thunderstorms will be possible again on Saturday afternoon for the
Big Island slopes. As previous discussions have mentioned,
however, precipitable water values will hover near or slightly
above normal (1.3 inches), so moisture availability will be a
limiting factor and may prevent enhanced trade wind showers and
isolated thunderstorms from being fully realized. A few updates
have been made to the forecast for Friday though Sunday with this
morning`s updates, but the overall philosophy remains unchanged.

Conditions will return to a more typical summertime trade wind
pattern by early next week as the low aloft moves away from the
state and weakens. High pressure will become re-established north
of the islands, resulting in locally breezy trades returning to
the state.

&&

.AVIATION...
Breezy trades will persist across the island chain today. SHRA
and low cigs could bring brief periods of MVFR conds over windward
and mauka locations. Otherwise, VFR conds should prevail.

No AIRMETs are in effect at this time. However, AIRMET Sierra for
mtn obsc may be needed later if SHRA coverage increases.

&&

.MARINE...
High pressure will dominate the central North Pacific through the
weekend and will strengthen even further early next week. A Small
Craft Advisory (SCA) remains in effect for the typically windy
waters around Maui and the Big Island through 6 PM this evening,
and may be needed through the weekend as channeled winds flirt
with SCA levels. Trade winds will increase to fresh to strong
levels early next week.

A series of south swells will keep south shore surf near the
summertime average through the weekend. Surf will drop below
normal levels for much of next week.

The current small northwest swell will keep north shore surf
slightly elevated through tomorrow, then fade out over the
weekend. Typical mostly flat summertime conditions will prevail
along north facing shores next week.

East shore surf will remain well below normal through the weekend,
then trend closer to seasonal levels next week as the trades
strengthen over and upstream of the islands.

&&

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

&&

$$

DISCUSSION...Vaughan
AVIATION...Walsh
MARINE...TS/ASB