Area Forecast Discussion
Issued by NWS Honolulu, HI

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000
FXHW60 PHFO 280627
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
827 PM HST Mon Jun 27 2022

.SYNOPSIS...
A strengthening high pressure system far north of the Hawaiian
islands will keep moderate to breezy trade winds blowing across
the state through the weekend. Passing clouds and showers will
drift through windward and mountain areas, favoring the overnight
to early morning hours. An upper low may briefly increase cloud
and shower coverage next weekend.

&&

.DISCUSSION...
The big picture satellite imagery this evening shows small cumulus
clouds riding into each island on the trade winds. A subtropical
jet stream in the upper levels continues to produce scattered
cirrus clouds over the island chain. Local radar imagery shows
isolated to scattered light shower coverage.

A strengthening surface high pressure system roughly 1,400 miles
north of the state will continue to produce moderate to breezy
trade winds across the region through the weekend. Model cross
sections continue to show subsidence temperature inversion heights
in the 6,000 to 8,000 foot range, allowing clouds to grow taller,
and produce passing showers over windward and mountain areas
through the week.

In the longer range forecast for the weekend, an upper level low
continues to track from southeast to northwest across the region.
Rainfall impacts with this system will heavily depend upon how
close this low center tracks relative to each island and are
highly variable this far out in the 5 to 7 day forecast time
period.

The evening forecast grids look good as there are no significant
changes to the forecast guidance over the past 12 to 24 hours.

&&

.AVIATION...
Moderate to locally breezy trade winds are expected to persist
through twenty-four hours and beyond. Bands of weak trade wind
showers will impact mainly windward slopes and coasts. Isolated
MVFR CIG and VIS are to be expected in passing showers. Otherwise,
VFR conditions will prevail statewide.

Across Leeward Big Island, weak land breezes will promote
overnight clearing most areas. However, residual cloudiness may
persist along the Kona and Kohala coasts due to a lee-side eddy
positioned just west of the Island. Offshore land breezes and
mostly clear skies Wednesday morning will be replaced by onshore
sea breezes and inland cloudiness by late afternoon.

AIRMET Tango is in effect for low-level mechanical turbulence
below 9000 feet over and downwind of island terrain. Conditions
are likely to persist through the day, Wednesday.

&&

.MARINE...
Fresh to strong easterly trade winds have returned and are here
to stay through the upcoming weekend as the ridge strengthens to
the north. Trades may become strong over most waters Friday
through the weekend as 1030-1035 mb high sets up due north of the
islands. Seas will respond and become rough, potentially reaching
the 10 ft Small Craft level over the waters south of the Big
Island and in the Alenuihaha Channel this weekend.

Surf along south facing shores will briefly trend down overnight
into Tuesday before the next pulse arrives out of the south. The
current south swell that came in above predicted and peaked at the
10 ft advisory level late Sunday through early Monday has notched
down this evening. Local buoy observations reflect this and show
the spectral peak centered around 15 seconds. Will monitor the
observations overnight and fine tune the surf forecast for the
Tuesday through Wednesday period accordingly - should see things
begin to pick up in those longer period bands through the night
down at buoy 51002 (see some small reflection in the 17-19 sec
bands, but small as of this writing). Expect this next pulse to
peak late Tuesday into Wednesday, then ease through the second
half of the week.

Surf along east facing shores will steadily trend up through the
week as the local and upstream trades increase. This should result
in rough conditions for easterly exposures by and through the
weekend.

Surf along north facing shores will remain at seasonal levels
(near flat) through the week.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory until 6 AM HST Tuesday for all south facing
shores.

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

&&

$$

DISCUSSION...Bohlin
AVIATION...Bedal
MARINE...Gibbs


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