403 
FXHW60 PHFO 210644
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
844 PM HST Fri Aug 20 2021

.SYNOPSIS...
Breezy trade wind conditions will persist into Saturday with 
clouds and showers favoring windward and mauka locations. The 
remnant low associated with former Hurricane Linda will move 
through the islands from east to west late Sunday through Monday, 
bringing the potential for strong winds and heavy rainfall to 
parts of the state. A return to a more typical trade wind pattern
is expected Tuesday through midweek.

&&

.DISCUSSION...
Recent satellite imagery showed the remnant low associated with 
former Hurricane Linda centered around 500 miles east of Hilo. An
ASCAT pass today confirmed a large area of strong- to gale-force
winds persisting to its north. The near-term guidance has
initialized well and depicts a slow spin-down process with strong
winds holding to its north as it approaches and moves through the
islands late Sunday through Monday. 

Despite the good model initialization and increasing forecast 
confidence, it remains difficult to pinpoint the areas/islands 
that will be impacted the most. Any slight deviation in its track 
to the north or south as it moves through could result in 
different impacts. While areas to its north will experience 
strong winds and heavy rainfall, areas positioned to its south 
will observe lighter winds and less rainfall. At this time, the 
latest model guidance remains tightly clustered, reflecting an 
east to west track through the central islands Sunday night 
through Monday. If this track verifies, a wind advisory may be 
required late Sunday through Monday for the smaller islands. In
addition to the winds, the threat of flash flooding will increase
where heavy rainfall becomes focused. 

A return to a more typical trade wind pattern is expected Tuesday
through midweek as the remnant low continues westward and away
from the area.

&&

.AVIATION...
Moderate to locally breezy trade winds and a ridge aloft will 
maintain stable trade wind weather into Saturday. A relatively 
shallow band of moisture will produce periods of MVFR conditions 
along windward slopes overnight, with AIRMET Sierra for mountain 
obscuration required in many areas. VFR will prevail over leeward
areas. Drier conditions are due on Saturday as the band clears 
and the circulation of former tropical cyclone Linda approaches 
the state.

With locally breezy trades in place, AIRMET Tango remains in 
effect for moderate low level turbulence over downwind of 
terrain. Winds will ease slightly overnight and gradually turn 
more northerly on Saturday as the circulation of former tropical 
cyclone Linda approaches the area. AIRMET Tango will likely be 
dropped, but areas of turbulence downwind of the islands will 
shift.

&&

.MARINE...
High pressure far north of area will generate moderate to locally
strong trade winds through tonight. A Small Craft Advisory (SCA) 
remains in effect for the typically windy zones around Maui County
and the Big Island until 6 AM HST Saturday. 

The wind and wave forecast for Sunday and Monday will highly 
depend on the track of the remnant low assoicated with former 
Tropical Cyclone Linda as it passes near or over the islands. The 
strongest winds will be on the north side of the remnant low and
the current forecast brings strong northeast winds to the waters 
north of Molokai and Oahu Sunday night through Monday afternoon,
then Kauai by Monday morning. Thunderstorms are also possible 
Sunday through Monday night across the coastal waters. A moderate
to locally breezy trade wind pattern should return Tuesday. 

The medium to long-period easterly swell from former Tropical 
Cyclone Linda will keep moderate surf along facing shores through 
Saturday. Surf along east facing shores will start to build Sunday
from locally generated wind waves as the remnant low moves near 
or over the islands. Surf heights may approach advisory levels for
the eastern half of the island chain Sunday, before reaching the 
western half Sunday night into Monday. How large the waves become 
is highly dependent on the eventual track and strength of the 
remnant low over the coming days. 

The current south swell will continue to slowly decline over the 
next couple of days. A series of small, moderate-period south 
swells will prevent surf from going flat into early next week.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch from Sunday morning through late Monday night 
for all Hawaii islands-

Small Craft Advisory until 6 AM HST Saturday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big 
Island Southeast Waters.

&&

$$

DISCUSSION...Gibbs
AVIATION...Birchard
MARINE...TS