Heavy Rain in Hawaii, August 16 to 17, 2022

Area Forecast Discussion
National Weather Service Honolulu HI
300 PM HST Tue Aug 16 2022

.SYNOPSIS...
A land and sea breeze pattern will continue into Wednesday,
favoring clearing tonight followed by interior clouds and a few
showers tomorrow afternoon. There is a chance of thunderstorms for
upslope portions of the Big Island tomorrow afternoon. Trades then
undergo modest strengthening becoming locally breezy and
supporting a return to a typical trade wind pattern by late
Thursday into Friday.

&&

.DISCUSSION...

The relaxed gradient in place over the islands will remain firmly
entrenched for the next 24 hours. A sea and land breeze pattern
will continue through this time with limited shower activity
focused over windward slopes tonight followed by another round of
interior clouds and a few showers tomorrow afternoon. The resident
upper low over the islands will provide some background forcing
for ascent, but dry mid-level air will still provide the necessary
stability to limit shower intensity. The exception will be upslope
sections of the Big Island. A couple towering cu were noted over
the summits on this afternoon's visible imagery, falling a bit
short of expectations today. The warm column will continue to be
somewhat of a hindrance tomorrow, though less so as cooler mid-
level temperatures beneath the upper low become established over
the eastern end of the state. As deeper moisture approaches the
Big Island from the east, the probability for a few locally heavy
showers and an isolated thunderstorm or two will be slightly
higher tomorrow compared to today, so thunder was added to the
forecast for upslope zones.

Subtropical ridging will rebound late this week as the
aforementioned longwave trough over the NE Pacific runs its
course. As heights recover, surface ridging will undergo modest
strengthening resulting in a gradual return of locally breezy
trades by late Thursday. This will in turn favor a typical stable
trade wind pattern through the weekend.

&&

.AVIATION...

With a weak ridge north of the islands, trade winds will be light
to moderate into Wednesday. This will result in localized sea
breezes into the early evening hours, and land breezes developing
overnight. Most areas will be VFR, but isolated MVFR is also
possible in showers over each isle through the late afternoon and
early evening as sea breeze conditions hold.

No AIRMETs are currently in affect.

&&

.MARINE...

A ridge north of the state will drive gentle to moderate trades
through tomorrow. This will allow development of localized
land and sea breezes. Terrain-induced wind acceleration may
produce pockets of choppy conditions near some coasts. Expect
fresh to strong easterly trades to return Thursday into the
weekend as the ridge strengthens and drifts north. Small Craft
Advisory conditions may occur across the windier waters and
channels over the eastern end of the state by Thursday.

Surf along south facing shores will remain small through the rest
of the week. Recent activity in the South Pacific will lead to an
upward trend in surf along south facing shores beginning this
weekend and lasting into early next week. Surf along east facing
shores will remain small through the first half of the week as the
trades ease. A return of choppy/short-period surf is expected by
the end of the week through the weekend as the trades return. Near
flat surf conditions will persist along north facing shores
through tomorrow. North facing shores may see a small bump
Thursday through the weekend as few small, short period, north and
northwest swells move through the area. Surf may continue to
trend up early next week as a slightly larger and longer period
northwest swell moves over the area.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
None.

&&

DISCUSSION...JVC
AVIATION...Kinel
MARINE...Powell