432 
FXHW60 PHFO 060143
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
343 PM HST Tue Oct 5 2021

.SYNOPSIS...
Moderate to locally breezy trade winds will strengthen Wednesday 
through Friday, with windy conditions anticipated over the 
weekend. Clouds and showers will tend to favor over windward and 
mauka areas with a few brief passing showers possible over some 
leeward locations. A wetter trade wind weather pattern is possible
early next week. 

&&

.DISCUSSION...
A 1030 mb high is centered about 1300 miles north northeast of 
the state. This places the islands in a moderate to locally breezy
trade wind environment. Moisture embedded in the trades is 
providing for some passing light showers over windward and mauka 
areas with most leeward areas remaining dry. 

The high will drift southward and strengthen over the next few 
days resulting in stronger trade winds. As we head into the weekend,
the pressure gradient is expected to tighten even more as weak 
low pressure passes by far south of the state. A Wind Advisory 
will likely be required for portions of the area. Trade winds 
speeds are expected to remain elevated on into early next week as 
strong high pressure remains to our north. 

No significant sources of upstream moisture are expected to 
affect the state through at least Saturday night. Clouds and 
passing showers will tend to favor windward and mauka areas with 
the trades sufficiently strong enough to blow a few light showers 
over to leeward area at times. The global models do show an 
increase in moisture moving in from the east southeast possibly as
early as Sunday. This would likely result in a wetter trade wind 
pattern to setting up across the area early next week. Confidence 
is rather low at the present time on this weather scenario become 
reality.

&&

.AVIATION...
Typical trade wind weather will prevail during the next 24 hours
with showers mainly focused over windward and mauka areas, mainly
overnight and early Wednesday morning. Brief MVFR will be possible
with any heavier showers, but VFR is forecast to prevail.
Throughout this time, locally breezy trades will gradually
strengthen, possibly becoming locally strong by Wednesday
afternoon.

AIRMET Tango for lee turbulence will remain in effect through the
forecast period.

&&

.MARINE...
High pressure centered far north of the area will maintain moderate
to fresh trade winds through tonight. The high will strengthen 
Wednesday, resulting in an increase in the trades over the 
coastal and offshore waters. A new, stronger high will develop far
to the north this weekend which will increase the trades further,
with gales in the Alenuihaha Channel possible. A Small Craft 
Advisory (SCA) that was in effect for the waters around Maui 
County and the Big Island has been expanded westward into the 
Kaiwi Channel and leeward Oahu waters to account for the 
strengthening trades.

A small, long period west-northwest swell is filling in across the
area. The swell should peak tonight through early Wednesday, then
will lower gradually during the second half of the week and 
through the weekend. Small, mainly background south swells can be 
expected through Thursday. A larger, long period south swell is 
forecast to arrive Thursday night, then peak Friday before slowly 
declining through the weekend. East-facing shores will continue to
be affected by choppy, short period surf. The strengthening of 
trades later this week will increase surf heights along the east- 
facing shores.

&&

.FIRE WEATHER...
With KBDI values still above 600, the strengthening winds over 
the next couple of days could result in Red Flag Warning 
conditions. Much will depend on if RH values get sufficiently low 
enough during the midday through late afternoon hours. A Fire 
Weather Watch has been issued for portions of state beginning noon
on Wednesday. The watch is currently posted through Thursday 
afternoon but the Watch or a Warning may need to be extended on 
into the weekend. 

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Wednesday afternoon through Thursday 
afternoon for Kauai Leeward-Oahu South Shore-Waianae Coast-Oahu 
North Shore-Olomana-Central Oahu-Waianae Mountains-Molokai 
Leeward-Maui Leeward West-Maui Central Valley-Leeward Haleakala-
Kona-Kohala-Big Island Interior. 

Small Craft Advisory until 2 PM HST Saturday for Oahu Leeward 
Waters-Kaiwi Channel-Maui County Windward Waters-Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big 
Island Southeast Waters.

&&

$$

DISCUSSION...Burke
AVIATION...JVC
MARINE...Kodama