NWS Bulletins for NPAC - MKWC
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Hawaiian Islands Synoptic Discussion and Guidance
964
FXHW60 PHFO 040137
AFDHFO
Area Forecast Discussion
National Weather Service Honolulu HI
337 PM HST Mon Jun 3 2024
.SYNOPSIS...
Trade winds will persist through Wednesday, then diminish and become
light and variable for the second half of the week. The island
atmosphere will be unstable through Tuesday, so windward trade
showers will be a little more active than normal. Additionally,
daytime heating of the slopes on the Big Island will bring the
potential for an afternoon thunderstorm. A trend toward much drier
weather will start Wednesday, and continue through the weekend.
&&
.DISCUSSION...
Breezy and somewhat wet trade wind weather through Tuesday will
trend much drier after mid-week as winds diminish and a ridge aloft
builds over the area.
In the meantime, a mid- and upper-level low centered just E of the
islands will drift W tonight, stall near the islands through
Tuesday, then move E on Wednesday. Although the atmosphere is not
especially moist, the low has prompted the development of isolated
(and somewhat unusual) high-based thunderstorms within 200 miles E
of the islands, due to steep mid- and upper-level lapse rates.
Afternoon soundings highlight the large amount of CAPE above ~10-12
thousand feet, with a sturdy subsidence inversion near 8000 ft
keeping surface-based parcels from tapping into this instability
aloft. The exception is on the Big Island, where afternoon heating
of the upper slopes may drive the development of an isolated
thunderstorm. Outside chance that a few more high-based
thunderstorms occur overnight E of the islands, and a slight chance
of thunderstorms has been added to windward waters. Otherwise,
windward showers may be a little more active than normal. As the low
moves E Wednesday, a strong mid-level ridge will build over the area
from the NW, leading to a very stable island atmosphere, thereby
significantly lowering inversion heights/rainfall chances.
A surface ridge N of the islands will remain nearly stationary
through Tuesday, supporting locally breezy trade winds. On Wednesday
and Thursday, unseasonably strong low pressure rapidly developing N
of the area will weaken the high and displace the ridge southward
near the islands, with winds becoming light and variable Thursday
and Friday. The ridge will gradually strengthen and move N over the
weekend, and light to moderate trade winds are expected. With
relatively light winds and a stable atmosphere, a mostly dry regime
is anticipated.
&&
.AVIATION...
Breezy to locally strong trades will deliver clouds and showers to
windward and mauka zones through the period. Nothing more than
isolated MVFR expected. The arrival of elevated instability favors a
chance for isolated thunderstorms over interior and upslope sections
of the Big Island and Mount Haleakala on Maui both this afternoon
and tomorrow afternoon.
AIRMET Tango for lee turb remains in effect.
&&
.MARINE...
Broad high pressure north of the state will maintain fresh to strong
trade winds into Tuesday, and a Small Craft Advisory (SCA) remains
in effect for all waters around the Big Island and Maui County and
select areas around Oahu and Kauai. Trades will decline late Tuesday
and Wednesday as the ridge of high pressure is weakened and pushed
southward, and the SCA will will likely be trimmed back to the
typical windy waters around the Big Island and Maui. The ridge will
erode further and be displaced farther south near Kauai Thursday
into Friday, causing the trades to diminish significantly and
possibly become disrupted. The SCA will be dropped completely by
this time. Increasing moderate trades are expected during the
weekend as the ridge lifts northward.
An extended run of southerly swell will continue this week and
almost certainly through mid June. The current south-southwest swell
is peaking today at around 3 feet 15 seconds, leading to surf near
the 10 foot High Surf Advisory level. This swell will gradually
decline Tuesday into Thursday, followed by a reinforcing south-
southwest swell late Thursday and Friday that will produce south
shore surf around seasonal average. As this swell lowers, a larger
swell will move through during the weekend, boosting surf around the
advisory level Sunday and Monday. A potentially larger swell is
looking increasingly likely to push surf well above the advisory
level late next week.
A small northwest swell building today will peak late tonight and
Tuesday, then linger into Thursday. A small short-period north-
northwest swell should follow later in the week. The fresh to strong
trade wind flow is producing elevated seas of 7 to 8 feet at 7 to 8
seconds. As trade winds decline Wednesday through Friday, rough east
shore surf will decline well below seasonal average, then remain
small through the weekend.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 PM HST Tuesday for Kauai Northwest
Waters-Oahu Leeward Waters-Kaiwi Channel-Maui County Windward
Waters-Maui County Leeward Waters-Maalaea Bay-Pailolo Channel-
Alenuihaha Channel-Big Island Windward Waters-Big Island Leeward
Waters-Big Island Southeast Waters.
&&
$$
DISCUSSION...Birchard
AVIATION...JVC
MARINE...Wroe
Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office
Narrow the Menu List
Select Time Limit: 12 hours | 24 hours | 48 hours | 72 hours | No time limit
Select Product Type: All | Routine Bulletins/FCSTS | Warnings/Watches/Advisories | HAWN Weather | Tropical | Marine | Aviation | Daily Obs | Special
Hawaiian Islands Synoptic Discussion and Guidance
964
FXHW60 PHFO 040137
AFDHFO
Area Forecast Discussion
National Weather Service Honolulu HI
337 PM HST Mon Jun 3 2024
.SYNOPSIS...
Trade winds will persist through Wednesday, then diminish and become
light and variable for the second half of the week. The island
atmosphere will be unstable through Tuesday, so windward trade
showers will be a little more active than normal. Additionally,
daytime heating of the slopes on the Big Island will bring the
potential for an afternoon thunderstorm. A trend toward much drier
weather will start Wednesday, and continue through the weekend.
&&
.DISCUSSION...
Breezy and somewhat wet trade wind weather through Tuesday will
trend much drier after mid-week as winds diminish and a ridge aloft
builds over the area.
In the meantime, a mid- and upper-level low centered just E of the
islands will drift W tonight, stall near the islands through
Tuesday, then move E on Wednesday. Although the atmosphere is not
especially moist, the low has prompted the development of isolated
(and somewhat unusual) high-based thunderstorms within 200 miles E
of the islands, due to steep mid- and upper-level lapse rates.
Afternoon soundings highlight the large amount of CAPE above ~10-12
thousand feet, with a sturdy subsidence inversion near 8000 ft
keeping surface-based parcels from tapping into this instability
aloft. The exception is on the Big Island, where afternoon heating
of the upper slopes may drive the development of an isolated
thunderstorm. Outside chance that a few more high-based
thunderstorms occur overnight E of the islands, and a slight chance
of thunderstorms has been added to windward waters. Otherwise,
windward showers may be a little more active than normal. As the low
moves E Wednesday, a strong mid-level ridge will build over the area
from the NW, leading to a very stable island atmosphere, thereby
significantly lowering inversion heights/rainfall chances.
A surface ridge N of the islands will remain nearly stationary
through Tuesday, supporting locally breezy trade winds. On Wednesday
and Thursday, unseasonably strong low pressure rapidly developing N
of the area will weaken the high and displace the ridge southward
near the islands, with winds becoming light and variable Thursday
and Friday. The ridge will gradually strengthen and move N over the
weekend, and light to moderate trade winds are expected. With
relatively light winds and a stable atmosphere, a mostly dry regime
is anticipated.
&&
.AVIATION...
Breezy to locally strong trades will deliver clouds and showers to
windward and mauka zones through the period. Nothing more than
isolated MVFR expected. The arrival of elevated instability favors a
chance for isolated thunderstorms over interior and upslope sections
of the Big Island and Mount Haleakala on Maui both this afternoon
and tomorrow afternoon.
AIRMET Tango for lee turb remains in effect.
&&
.MARINE...
Broad high pressure north of the state will maintain fresh to strong
trade winds into Tuesday, and a Small Craft Advisory (SCA) remains
in effect for all waters around the Big Island and Maui County and
select areas around Oahu and Kauai. Trades will decline late Tuesday
and Wednesday as the ridge of high pressure is weakened and pushed
southward, and the SCA will will likely be trimmed back to the
typical windy waters around the Big Island and Maui. The ridge will
erode further and be displaced farther south near Kauai Thursday
into Friday, causing the trades to diminish significantly and
possibly become disrupted. The SCA will be dropped completely by
this time. Increasing moderate trades are expected during the
weekend as the ridge lifts northward.
An extended run of southerly swell will continue this week and
almost certainly through mid June. The current south-southwest swell
is peaking today at around 3 feet 15 seconds, leading to surf near
the 10 foot High Surf Advisory level. This swell will gradually
decline Tuesday into Thursday, followed by a reinforcing south-
southwest swell late Thursday and Friday that will produce south
shore surf around seasonal average. As this swell lowers, a larger
swell will move through during the weekend, boosting surf around the
advisory level Sunday and Monday. A potentially larger swell is
looking increasingly likely to push surf well above the advisory
level late next week.
A small northwest swell building today will peak late tonight and
Tuesday, then linger into Thursday. A small short-period north-
northwest swell should follow later in the week. The fresh to strong
trade wind flow is producing elevated seas of 7 to 8 feet at 7 to 8
seconds. As trade winds decline Wednesday through Friday, rough east
shore surf will decline well below seasonal average, then remain
small through the weekend.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 PM HST Tuesday for Kauai Northwest
Waters-Oahu Leeward Waters-Kaiwi Channel-Maui County Windward
Waters-Maui County Leeward Waters-Maalaea Bay-Pailolo Channel-
Alenuihaha Channel-Big Island Windward Waters-Big Island Leeward
Waters-Big Island Southeast Waters.
&&
$$
DISCUSSION...Birchard
AVIATION...JVC
MARINE...Wroe
Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office