Drought in Hawaii, November 1 to 30, 2021

Area Forecast Discussion
National Weather Service Honolulu HI
823 PM HST Sun Oct 31 2021

.SYNOPSIS...
Mostly dry and stable conditions with light and variable winds
will continue into Tuesday. The best chance for a few light
showers will be driven by sea breezes through the afternoon
periods. A return of a more typical trade wind pattern is expected
by Wednesday, which should continue through the weekend. A band of
moisture drifting southward into the smaller islands will support
better windward shower coverage through the second part of the
week.

&&

.DISCUSSION...
Guidance remains persistent and depicts the weak ridge lingering
over the islands into Tuesday due to broad upper troughing over the
region and a couple of fronts passing to the north. The light
westerly background flow in the islands will continue through Monday
night, then shift out of the north to northeast direction Tuesday.
This will allow the land and sea breeze regime to hold with
clearing conditions overnight through the mornings followed by
some cloud build ups that may produce a few light showers through
the afternoon hours over interior areas. The best shot for these
showers will remain over Kauai and Oahu where more moisture
resides near the tail-end of the passing fronts to the north.

A transition period is anticipated Tuesday through Wednesday as the
a ridge noses eastward trailing the front passing to the north. The
flow will shift out of the north-northeast later Tuesday, followed
by a return of moderate easterly trades Wednesday. Clouds and
showers will shift back over windward and mountain locations, with
the best chances being overnight through the early morning hours. A
residual band of moisture associated with the tail-end of the
aforementioned front may sag southward into the smaller islands
through the second half of next week, which could support better
shower coverage.

&&

.AVIATION...
A dry and stable airmass continues over the region, with light
winds. The light winds allow sea breezes to develop during the
afternoon with clouds and isolated showers over interior and
leeward areas, particularly on Kauai and Oahu where moisture is a
bit higher than across Maui County or the Big Island. Overnight
land breezes should largely clear out the islands. This pattern is
expect to repeat itself Monday. VFR conditions are expected to
prevail however some isolated MVFR conditions are possible within
some pockets of lower clouds or showers during the afternoon and
evening hours. Any showers that do form should remain light.

There are currently no AIRMETs in effect and, at this time, no
AIRMETs are anticipated throughout the forecast period.

&&

.MARINE...
With a high pressure ridge near the islands, winds have been light
across the coastal waters. High pressure will begin strengthening
north of the state by Tuesday night into Wednesday, signaling
the return of trade winds. By Thursday, trades will become
moderate to breezy.

The first in a series of northwest to north swells over the next
week or so has begun affecting local waters. A High Surf Advisory
(HSA) is in effect for most north- and west-facing shores from
Niihau to Maui. As this swell lowers Monday; another, larger,
long-period swell will begin to move through beginning Monday
night into Tuesday. The surf generated by this swell will likely
warrant a High Surf Warning (HSW) for most north- and west-facing
shores beginning early Tuesday, as surf is expected to reach at
least 25 feet (faces) along north-facing shores. The HSW will
likely be in effect into Wednesday before being replaced by an
HSA. The swell causing the higher surf will slowly subside through
the end of the work week. And early on, swell heights will reach
at least 10 feet, so a Small Craft Advisory will be necessary for
those waters exposed to the incoming swell, beginning Monday
night.

Elsewhere, no significant swells are expected along east- and
south-facing shores through the new week.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory until 6 AM HST Monday for Niihau-Kauai
Leeward-Waianae Coast-Oahu North Shore-Maui Windward West-Kauai
North-Molokai Windward-Molokai North-Molokai West-Maui Central
Valley North-Windward Haleakala.

&&

DISCUSSION...Gibbs
AVIATION...M Ballard
MARINE...Kinel