Drought in Hawaii, July 12 to 31, 2022

Area Forecast Discussion
National Weather Service Honolulu HI
847 PM HST Mon Jul 11 2022

.SYNOPSIS...
Increasing moisture associated with the remnants of former
Hurricane Bonnie will drive rainfall chances up late Tuesday
through midweek, especially over the eastern end of the state.
Although most of the shower activity will favor our typical
windward and mauka locations, expect some to make it into our dry
leeward spots with the breezy trades in place. On the heels of
Bonnie will be the remnants of Hurricane Darby moving into the
area, which could bring wet and windy conditions to portions of
the state Friday night through the weekend.

&&

.DISCUSSION...
Satellite-derived precipitable water showed the leading edge of
moisture associated with the remnants of former Hurricane Bonnie
around 300 miles east of Hilo. This leading edge should arrive
over the eastern end of the state through the morning hours
Tuesday, then steadily increase statewide late Tuesday through
midweek as it moves through. A combination of breezy trades,
increasing moisture, and the trade wind inversion lifting toward
or around 10,000 ft will support better rainfall chances Tuesday
night through Wednesday. Some of these showers will make it into
our dry leeward areas with the breezy trades and elevated
inversion - best chance through the early morning hours Wednesday.

Once the remnants of Bonnie shifts away from the area Thursday
through Friday, the focus will shift on Darby, which is currently
located about 1900 miles east of Hilo. Darby is forecast to cross
over into the Central Pacific Hurricane Center area of
responsibility Thursday as a tropical storm, then likely a post
tropical system by Friday as it begins to make its approach to the
islands over cooler waters. Although there remains some timing
differences between the various sources of guidance, the potential
for a wet and windy weekend is increasing as Darby's remnants
move through. More details will follow over the next few days as
confidence increases.

&&

.AVIATION...
A high pressure ridge far north of the Hawaiian Islands will keep
moderate to breezy trade winds in the forecast on Tuesday. Clouds
will continue to drift into each island on the trade winds
producing passing showers mainly over windward and mountain areas
with isolated MVFR conditions possible especially in the overnight
to early morning hours. Cloud and shower coverage will begin to
increase over the windward Big Island by Tuesday night, as
moisture from the remnants of former tropical cyclone Bonnie begin
to drift into the region from the east. This deeper tropical
moisture will slowly drift westward to other islands with enhanced
shower activity spreading across the region on Wednesday.

AIRMET Tango remains in effect for moderate low level turbulence
over and downwind of all island mountains. This AIRMET will
likely continue through at least Tuesday.

&&

.MARINE...
A somewhat active period is expected in Hawaiian waters over the
next week. Fresh to strong trade winds will prevail for most of
the time. A bit of a surge in the trade winds, and an increase in
seas and shower coverage, is expected late Tuesday into Wednesday
as the remnants of tropical cyclone Bonnie move from E to W
across the area, briefly tightening the low-level pressure
gradient. Another surge in trade winds, sea heights and gusty
showers are possible this weekend as weakening tropical cyclone
Darby approaches from the E.

Surf along S facing shores will be on the increase over the next
day or two as a long-period S swell arrives. Surf may ease a little
thereafter, but a powerful long-period (20-22 seconds) S swell
will arrive late in the week, extending through the weekend. Peak
surf heights with this swell will easily reach High Surf Advisory
criteria (10 foot faces), with potential for surf to reach High
Surf Warning levels along S shores (15 foot faces).

Surf along E facing shores will remain elevated and rough through
the week, especially as the winds ramp up through the midweek
period, and again this weekend. Swells generated by tropical
cyclone Darby will probably be biggest along E facing shores of
the Big Island, where a High Surf Advisory may be required.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 PM HST Wednesday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big
Island Southeast Waters.

&&

DISCUSSION...Gibbs
AVIATION...Bohlin
MARINE...Birchard