Area Forecast Discussion
Issued by NWS Honolulu, HI

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000
FXHW60 PHFO 120647
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
847 PM HST Mon Mar 11 2024

.SYNOPSIS...
A stubborn upper level low will gradually weaken and shift east
tonight and Tuesday, allowing for a slow decrease in cloud cover,
while winds also weaken across the state. Showers will favor
windward areas tonight, then interior and leeward areas Tuesday
afternoon. Another disturbance aloft could bring some showers into
leeward areas late Tuesday night and Wednesday, with light winds
also bringing a few afternoon showers to leeward areas Wednesday
afternoon. A cold front will usher in some cooler air and bring an
increase in showers to north and northeast facing slopes and
coasts Wednesday night through Friday as it moves through. Light
to moderate trades appear in store for the weekend, with rain
chances remaining highest over windward sections of the eastern
islands.

&&

.DISCUSSION...
Currently at the surface, a 1028 mb high is centered around 1050
miles northeast of Honolulu, while a cold front is locatged around
1100 miles west-northwest of Kauai. Moderate to breezy trade winds
prevail across the island chain this evening, strongest over the
eastern end of the state. Infrared satellite imagery shows
abundant cloud cover resulting in mostly cloudy to overcast
conditions. Radar imagery shows scattered showers moving into
windward slopes and coasts, with a few showers reaching leeward
areas at times. Main short term focus revolves around trade wind
trends and rain chances during the next couple days.

The high northeast of the state will lift northeastward and
further away from the islands during the next couple days, as a
cold front approaches from the northwest. In response, the trades
will begin to ease over the western islands later tonight and over
the eastern islands on Tuesday. The winds will likely be light
enough over the western islands and the more sheltered sections of
the eastern islands to allow for sea breeze development Tuesday
afternoon. Winds will ease further Tuesday night with land
breezes common statewide by daybreak Wednesday, followed by sea
breeze development during the day. A cold front will then
gradually push southeast down the island chain Wednesday night
through Friday, ushering in moderate northerly winds which will
slowly shift northeasterly by daybreak Friday. The front will
stall out and dissipate in the vicinity of the Big Island on
late Friday through Saturday, while a weak high slides by to the
north of the state. Moderate northeast trades will hold on Friday,
before easing into the light to moderate range over the weekend.
High pressure north of the state could bring a slight increase in
the trade wind speeds early next week.

As for the remaining weather details, showers will favor windward
slopes and coasts tonight and Tuesday morning, with sea breezes
allowing some interior and leeward shower development Tuesday
afternoon. Showers should diminish fairly quickly Tuesday evening,
with a few showers still moving into windward and southeast facing
slopes of Maui and the Big Island. A shortwave trough approaching
from the west may draw some deeper moisture northward later
Tuesday night and early Wednesday, increasing shower chances over
leeward sections of the smaller islands as southwesterly boundary
layer flow gets a boost from an approaching cold front.
The shortwave trough is expected to exit east of the state
Wednesday afternoon, with sea breezes bringing a few interior and
leeward showers once again.

A cold front moving southeastward through the state will then
usher in some cooler air and bring increasing showers to north
and northeast facing slopes and coasts as it moves through
Wednesday night through Friday. Model solutions are showing some
differences in the progressiveness of the front Friday through the
weekend, lowering forecast confidence. Overall, it appears that
rain chances will remain highest over the eastern end of the state
Friday through the weekend as the front stalls out and dissipates
in this area, while the western islands may see very little rain
as the drier post-frontal airmass settles in.

&&

.AVIATION...
Breezy easterly trades will gradually weaken tonight as high
pressure north of the state moves east.

An upper trough to the south of the region will continue to
stream mid and upper level clouds over the islands through the
forecast period. Trade flow in the lower levels will keep shower
activity mainly limited to windward areas. However, isolated
showers may occasionally push over the higher terrain and onto
leeward sides.

VFR conditions will generally prevail, but brief periods of MVFR
ceilings and visibility will be possible in any of the heavier
showers.

AIRMET Tango remains in effect below 8000 feet over and south
through west of mountains for tempo moderate turbulence. These
conditions will likely improve tonight into Tuesday morning.
AIRMET Tango also remains in effect for tempo moderate turbulence
aloft between 120-FL280 for tempo moderate turbulence. See SIGMET
PAPA series over the islands for areas expected severe turbulence
between Fl280-Fl350.

&&

.MARINE...
The high pressure system north of the islands producing fresh to
strong easterly trade winds will move farther east tonight as a
weakening cold front approaches the Hawaii region from the
northwest. Wind speeds will blow from the east-southeast direction
by Tuesday diminish over the next few days. Light to gentle
westerly to northwesterly winds remain in the forecast from
Tuesday night through Wednesday ahead of the approaching front.
Land and sea breeze winds will develop along near shore coastal
waters from Tuesday afternoon through Wednesday. Moderate to
locally fresh northerly winds will fill in as the front advances
down the island chain Wednesday night through Thursday night,
then blow out of the northeast Friday as the ridge builds in
behind the front. Gentle to moderate northeast trade winds are
forecast through the weekend.

Surf along exposed north and west facing shores will peak tonight
as a long period northwest swell fills in and is then reinforced
by another northwest swell on Tuesday. These two swells should
keep moderate surf along north and west facing shores through the
day Tuesday then trend downward by Wednesday.

A more significant northwest to north-northwest swell is expected
late Wednesday night through the second half of the week in
response to a developing hurricane force low analyzed today around
2000 nm northwest of the islands across the far northwest
Pacific. Guidance shows a good sized area of gale- to storm-force
winds focused towards Hawaii within the 310-340 degree directional
bands through the first half of the week as the system moves
eastward. Surf heights could reach warning levels during the peak
of this event from late Thursday through Friday if this scenario
evolves as predicted.

Surf along east facing shores will remain rough through tonight,
then begin to ease Tuesday through midweek as the trades diminish.
Surf along south facing shores should gradually decline and
return to background levels by Wednesday as the current small
south-southwest swell dissipates.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 AM HST Tuesday for Kaiwi Channel-
Maui County Leeward Waters-Maalaea Bay-Pailolo Channel.

Small Craft Advisory until 6 PM HST Tuesday for Maui County
Windward Waters-Alenuihaha Channel-Big Island Windward Waters-
Big Island Leeward Waters-Big Island Southeast Waters.

&&

$$

DISCUSSION...Jelsema
AVIATION...Thomas
MARINE...Bohlin


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