Drought in Hawaii, November 23 to 30, 2021

Area Forecast Discussion
National Weather Service Honolulu HI
757 PM HST Mon Nov 22 2021

.SYNOPSIS...
Moderate to breezy easterly trade winds will hold into Tuesday,
with clouds and showers favoring windward and mauka locations.
Trade winds will trend down late Tuesday through midweek,
potentially enough for a localized land and sea breeze regime to
become established. Another area of moisture will approach and
move into the eastern end of the state from the east late Tuesday
night through Wednesday, which will keep the rain chances up
going into the second half of the week. Easterly winds should
remain light enough for localized land and sea breeze conditions
to continue through the upcoming weekend as a series of fronts
pass to the north.

&&

.DISCUSSION...
Guidance remains in good agreement through midweek and depicts
moderate easterly trades holding into Tuesday before easing
tomorrow afternoon through midweek as a weakness forms in the
ridge to the north due to a passing front. An area of moisture
moving through from east to west has provided more rainfall than
originally expected today for windward areas from Oahu to the Big
Island (impressive given inversion heights were below 5 kft early
this morning) - where peak totals have exceeded an inch at the
gauges over the past 12 to 15 hours. As this area continues
westward overnight, Kauai will get into the mix where half of an
inch to an inch will be possible by daybreak Tuesday.

Another area of moisture will approach and move into the eastern
end of the state from the east late Tuesday night through
Wednesday. This combined with lowering upper heights as a weak
upper low drifts southwestward near the eastern end of the state
will keep the rainfall chances in the forecast going into the
second half of the week. Although the best shower coverage will
favor windward areas of Maui and the Big Island, where PWs are
projected to climb into the 1.5" to 2" range and hold into Friday,
some increase in shower coverage will be possible over the
western end as well. Trades will remain on the light side through
the upcoming weekend due to a progressive pattern ongoing across
the northern Pacific featuring a series of fronts.

&&

.AVIATION...
A narrow band of low level moisture moving within the gentle to
moderate trade wind flow will continue to produce widespread MVFR
conditions across windward slopes of all islands this evening,
followed by improving conditions from east to west late tonight. A
mid level ridge is maintaining stable conditions and capping cloud
tops near 8,000 ft, but the low level moisture is producing
ceilings at or below 2,000 ft in many windward areas,
necessitating AIRMET Sierra for mountain obscuration. Expect
slightly weaker trade winds Tuesday and prevailing VFR, with
lingering MVFR conditions possible in the morning across windward
Kauai.

&&

.MARINE...
A high pressure ridge will drift into the northern offshore
waters and remain in a weakened state as a cold front passes by
far to the north of the island chain. Moderate easterly trade
winds will keep wind speeds below Small Craft Advisory conditions
for most of the coastal waters through the weekend.

A northwest swell moving into the region tonight will produce a
slight bump for surf along north and west facing shores through
Tuesday. A larger northwest swell will arrive on Wednesday, likely
bringing advisory level surf along exposed north and west facing
shores by Thanksgiving Day. This northwest swell energy will show
decreasing trends on Friday and then hold at fun size levels through
the weekend. Surf heights along east facing shores will remain
small with nearly flat conditions along south facing shores of all
islands.

&&

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

&&

DISCUSSION...Gibbs
AVIATION...Wroe
MARINE...Bohlin