Pepeekeo, Hawaii Weather Forecast Discussion

148
FXHW60 PHFO 191312
AFDHFO
Area Forecast Discussion
National Weather Service Honolulu HI
312 AM HST Fri Sep 19 2025
.SYNOPSIS...
Moderate to breezy trade winds remains in the forecast for the
foreseeable future. Brief passing showers will continue today,
mainly over windward and mountain areas in the overnight to early
morning hours. The unstable cloud remnants of an old frontal band
will drift through the islands later this afternoon into Saturday,
boosting cloud and rain shower coverage for all islands. These
enhanced clouds and showers will linger over the windward slopes
of the Big Island through Sunday, while other islands will return
to a more typical brief passing shower pattern. By next week
Tuesday, a weak upper level low drifts over the Hawaii Region,
enhancing clouds and showers with the potential for enhanced wet
weather trends.
&&
.DISCUSSION...
The morning satellite picture shows the subtropical jet stream
producing high level cirrus clouds over the Big Island as an
long unstable low level band of clouds associated with an old
East Pacific cold front rides into the Hawaiian Islands on the
trade winds.
A high pressure ridge north of the island chain will keep moderate
to breezy trade winds in forecast for the foreseeable future. A
long unstable cloud band, associated with the remnants of an old
East Pacific cold front will ride into the islands on the trade
winds later this afternoon. This low level cloud band will push
temperature inversion into the 7,000 to 10,000 foot range and
drive clouds to higher heights, allowing wet weather trends for
all islands starting later this afternoon and lasting into
Saturday. Fairly significant storm total rainfall amounts in the
0.50 to 1.00 inch range will tend to favor windward and mountain
areas. However, the strongest showers in this band will likely
bring some much needed rainfall, although at lower amounts, to
favored leeward areas. The southern portion of this unstable
cloud band will linger along the windward slopes of the Big Island
through Sunday. As more stable conditions will return to the rest
of the state.
Back to more typical brief passing showers in a moderate to breezy
trade wind pattern through Monday. A weak upper level low drifts
over the Hawaii Region by next week Tuesday, briefly boosting
shower activity across the state through early Wednesday morning.
We increased precipitation chances to account for this cold core
unstable upper low over the islands during this time period.
&&
.AVIATION...
Moderate to breezy trade winds will continue for the next several
days. Although some clouds and showers embedded within the trades
will be possible for windward and mountain areas, VFR flight
conditions are expected to prevail for most locations.
AIRMET Tango remains in effect for moderate low level turbulence
over and downwind of island terrain. This AIRMET will likely be
needed for the next several days as breezy trades persist.
&&
.MARINE...
High pressure to the north-northeast of the area will remain in
place for the next several days, keeping moderate to locally
strong trade winds across the islands. A Small Craft Advisory
(SCA) is in effect for the typical windy areas around Maui and the
Big Island until 6 PM Saturday evening. Trades should gradually
ease Sunday into early next week as the high weakens to our north.
Surf along south facing shores should see an increase this weekend
as a small to moderate, long-period, south-southwest swell
gradually fills in later today into Saturday and peaks late
Saturday into Sunday. Surf heights should rise back up to near or
above the September averages over the weekend then gradually
decline next week.
Surf along north facing shores saw a small increase yesterday due
to a short-period north swell. This small bump is expected to
peak today, followed by a short period north-northwest swell this
weekend.
Moderate to locally strong trades near and upstream of the area
will lead to choppy conditions along east facing shores over the
next several days.
&&
.FIRE WEATHER...
Humidity levels and wind speeds will remain just below critical
fire weather thresholds this week. A few periods of unsettled
weather conditions will increase humidity levels, clouds and
shower chances starting later this afternoon through Saturday,
with another round from Tuesday morning into Wednesday. Temperature
inversion heights near the Big Island and Maui today will range
from 7,000 to 8,000 feet elevation.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 PM HST Saturday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big
Island Southeast Waters.
&&
$$
DISCUSSION...Bohlin
AVIATION...Bohlin
MARINE...Walsh
FIRE WEATHER...Bohlin

NWS HFO Office Area Forecast Discussion