Drought in Hawaii, August 1 to 31, 2022

Area Forecast Discussion
National Weather Service Honolulu HI
833 PM HST Sun Jul 31 2022

.SYNOPSIS...
Strong trade winds will continue into Monday, with windward
clouds and showers remaining limited. A transition period is
expected late Monday through midweek as an upper disturbance and
surface trough approach and move in from the east. Diminishing
trade winds along with increasing moisture may be enough to
trigger a few showers over our dry leeward areas through the
afternoon hours where sea breezes form Wednesday through the
second half of the week.

&&

.DISCUSSION...
Evening satellite imagery showed a remnant band of low clouds
associated with an old boundary far northeast of the islands.
Guidance highlights this moisture axis and shows it moving
through early Monday. Despite a strong upper ridge in place and
subsidence inversion, this added low-level moisture combined with
breezy trades will likely translate to increasing shower coverage
for some windward and mauka locations as it moves through.
Satellite data showed a surge in northeast winds trailing it
earlier today, which may be experienced locally once it makes it
into the area Monday (shown in the hi-res WRF guidance). As a
result, expect the gusty trades to linger for another day,
especially over the Kohala area of the Big Island, Kahoolawe, and
Lanai (wind gusts are ranging from 40 to 50 mph this evening)
where the Wind Advisory has been extended.

Trade winds will begin to ease late Monday through midweek as an
upper low moves in from the east and the gradient begins to relax.
An increase in deep layer moisture combined with the added
instability and surface trough could fuel localized heavy showers,
and a thunderstorm or two can't be ruled out over the eastern end
of the state Tuesday night through Wednesday. Once the surface
trough moves through, the low-level flow will shift out of the
east-southeast Wednesday into the second half of the week. This
pattern shift will translate to a land and sea breeze regime
setting up, which will drive rainfall chances up over our leeward
areas through the afternoon and evening periods.

&&

.AVIATION...
Breezy to strong trade winds will continue through Monday. A
broken band of low clouds and showers will move southward through
the islands tonight and Monday, bringing some MVFR cigs/vsbys to
windward areas as it moves through. AIRMET Sierra will likely be
needed for mountain obscuration across portions of the island
chain later tonight.

AIRMET TANGO remains in effect for moderate low level turbulence
over and downwind of the terrain of all islands. This AIRMET will
continue through at least Monday.

&&

.MARINE...
A strong high pressure system far north of the Hawaiian Islands
will keep fresh to strong trade winds blowing through Monday. A
Small Craft Advisory remains in effect for all Hawaiian waters
through Monday afternoon. The trade winds will weaken from Monday
night through Tuesday as a weak trough moves into the region.
Lighter winds are expected from Wednesday through Friday with
nearshore land and sea breezes developing. More unstable
conditions arrive with an upper level disturbance potentially
producing isolated thunderstorms over the Big Island waters from
late Tuesday through Wednesday.

A south swell currently moving into the region will elevate south
shore surf to near summertime norms through Tuesday. Only small
background south swells are then expected from Wednesday through
the weekend, keeping lower surf heights along south facing shores.

Surf along east facing shores will hold steady through Tuesday
due to strong trades over and upstream of the islands. The trade
wind swell will lower Wednesday and remain below average through
the weekend. Distant tropical activity in the Eastern Pacific
will send a small, medium period east swell into the region from
Tuesday night through Friday, producing a slight boost to east
shore surf. Surf along north facing shores will remain nearly
flat this week.

&&

.FIRE WEATHER...
The Red Flag Warning has been extended through the day Monday.
Trade wind speeds should remain breezy, but slightly weaker than
today. Some clouds and showers will move in with the trades
tonight, but will shift back to dry and stable by midday with the
likelihood of reaching Red Flag conditions by afternoon.
Therefore, have extended the Red Flag Warning through Monday.
Winds will trend down by Monday night and the warning will not be
necessary after that.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 6 PM HST Monday for Niihau-Kauai Leeward-
Oahu South Shore-Waianae Coast-Molokai Leeward-Lanai Makai-Lanai
Mauka-Kahoolawe-Maui Windward West-Maui Leeward West-Maui
Central Valley-Leeward Haleakala-Kona-South Big Island-Kohala-
Big Island Interior.

Wind Advisory until 6 PM HST Monday for Lanai Mauka-Kahoolawe-
Kohala-Lanai Windward-Lanai Leeward-Big Island North.

Small Craft Advisory until 6 PM HST Monday for all Hawaiian
waters-

&&

DISCUSSION...Gibbs
AVIATION...Jelsema
MARINE...Bohlin