NWS Bulletins for NPAC - MKWC
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Hawaiian Islands Synoptic Discussion and Guidance
461
FXHW60 PHFO 251351
AFDHFO
Area Forecast Discussion
National Weather Service Honolulu HI
351 AM HST Sat Jan 25 2025
.SYNOPSIS...
A low pressure system far north of the Hawaiian Islands is
dragging a low level boundary over the eastern islands this
morning. Chances for another round of showers and isolated
thunderstorms are possible over north and east slopes of the Big
Island this afternoon. This low level boundary will weaken and
lift northwestward ahead of the next shallow cold front due to
move through the island chain from Monday into Tuesday. Moderate
to breezy trade wind will fill in as the front passes through each
island. A very wet weather pattern with kona winds may develop by
next week Thursday.
&&
.DISCUSSION...
The tail end of a low level trough will linger near the eastern
slopes of the Big Island today enhancing some afternoon showers
with the potential for another round of isolated thunderstorms
with brief heavy rainfall from Laupahoehoe to Hilo to Puna. This
boundary near the Big Island will weaken and slowly lift
northwestward over the next two days. Heavy rainfall over the
north and east slopes of the Big Island last night produced
between 2 and 4 inches of rainfall based on a combination of radar
rainfall estimates and rain gauge observations. No significant
flooding, As of 4 AM HST this morning, was reported by local Big
Island officials.
Looking into the near future, we see periods of wet weather shaping
up across the Hawaii region through Tuesday. A combination of two
low level boundaries, a trough near the Big Island and an
approaching cold front, combine forces with an upper level
disturbance to enhance showers across the state. Light to moderate
trade winds will continue as a shallow front passes through the
islands from Monday into Tuesday. Shower activity will favor north
and east slopes of each island, and all areas along the passing
frontal cloud band. Cool northerly winds will move in along and
behind this front as it passes through each island. This frontal
boundary will diminish into a trough and stall near the Big Island
and Maui from late Tuesday into Wednesday, and then slowly lift
northward as more unstable southerly kona winds begin to develop.
By next week Thursday, the weather pattern changes significantly
with kona winds developing over the islands as a cut off low moves
into the region. Heavy rainfall and thunderstorms impacts are
possible from Thursday into Friday as this system passes quickly
through the region. Model solutions are still trying to settle on
the track and intensity of this next potentially impactful
rainfall event. Island by island impacts will depend heavily on
the track and intensity of next weeks system. Thunderstorms and
periods of heavy rain for some islands should be expected.
Flooding threats are possible as some heavy rain bands or
thunderstorms may train over one or two islands. Stay tuned for
more details as the forecast time period grows shorter and the
forecast guidance tunes into this potential kona low weather
event.
&&
.AVIATION...
Light to locally moderate trade winds will steer bands of clouds
and light showers off the Pacific towards windward slopes and
coasts. Showers this morning will be most active along east
facing slopes of the Big Island and Maui, but will spread across
windward Molokai and Oahu later today.
The airmass over the state remains unstable. Daytime heating is
expected to drive widespread afternoon convection, especially over
the eastern end of the state. Most recent satellite and radar
imagery indicates moderate to heavy showers lingering just off the
east coast of the Big Island. These showers should taper off in
the next few hours. Heavy showers or thunderstorms will likely
redevelop over Interior and Windward portions of the Big Island
this afternoon.
AIRMET Sierra remains posted for mountain obscuration across east
facing slopes of both the Big Island and Maui. Sierra will likely
be canceled by mid-morning, but conditions could redevelop later
in the day.
&&
.MARINE...
Light to moderate northeast to east winds will persist into
Sunday as a weak surface ridge lifts north of the state. Pockets
of fresh breezes may develop over the typically windier waters and
channels from Maui County to the Big Island during this time.
Moderate to fresh north to northeast winds are expected to return
over the western half of the state late Sunday through Monday,
then extend statewide from Tuesday through Wednesday as another
front moves into the area.
Surf along shores exposed to northerly swells will gradually
lower through the weekend as a north-northwest swell eases.
Offshore buoys to the north and northwest confirm this downward
trend, showing a wide range of short- to medium-period north-
northwest energy. As a result, the surf has fallen below the
advisory level overnight and will dip below average from Sunday
through Monday.
With a blocking high persisting over the northwest Pacific, the
primary swell source will remain out of the north next week,
featuring a mix of short-period wind waves associated with the
northerly winds expected locally and medium-period northerly
swells. Forecast guidance indicates an upward trend in surf
beginning Tuesday and continuing into late next week due to a
potential gale forming well to the north. Heights could near or
reach the advisory level around Wednesday, if this scenario
evolves.
Surf along east-facing shores, not exposed to northerly swells,
will remain small each day due to the lack of trades locally and
upstream.
Surf along south-facing shores will remain around the seasonal
average, with mainly a mix of short-period southeast and an
occasional background south swell moving through.
&&
.FIRE WEATHER...
Wind speeds will remain below critical fire weather thresholds
through the middle of next week. Moisture levels rise swiftly from
Thursday onward with southerly winds bringing another round of
widespread rainfall in the forecast for all islands.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION...Bohlin
AVIATION...Bedal
MARINE...Gibbs
FIRE WEATHER...Bohlin
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
461
FXHW60 PHFO 251351
AFDHFO
Area Forecast Discussion
National Weather Service Honolulu HI
351 AM HST Sat Jan 25 2025
.SYNOPSIS...
A low pressure system far north of the Hawaiian Islands is
dragging a low level boundary over the eastern islands this
morning. Chances for another round of showers and isolated
thunderstorms are possible over north and east slopes of the Big
Island this afternoon. This low level boundary will weaken and
lift northwestward ahead of the next shallow cold front due to
move through the island chain from Monday into Tuesday. Moderate
to breezy trade wind will fill in as the front passes through each
island. A very wet weather pattern with kona winds may develop by
next week Thursday.
&&
.DISCUSSION...
The tail end of a low level trough will linger near the eastern
slopes of the Big Island today enhancing some afternoon showers
with the potential for another round of isolated thunderstorms
with brief heavy rainfall from Laupahoehoe to Hilo to Puna. This
boundary near the Big Island will weaken and slowly lift
northwestward over the next two days. Heavy rainfall over the
north and east slopes of the Big Island last night produced
between 2 and 4 inches of rainfall based on a combination of radar
rainfall estimates and rain gauge observations. No significant
flooding, As of 4 AM HST this morning, was reported by local Big
Island officials.
Looking into the near future, we see periods of wet weather shaping
up across the Hawaii region through Tuesday. A combination of two
low level boundaries, a trough near the Big Island and an
approaching cold front, combine forces with an upper level
disturbance to enhance showers across the state. Light to moderate
trade winds will continue as a shallow front passes through the
islands from Monday into Tuesday. Shower activity will favor north
and east slopes of each island, and all areas along the passing
frontal cloud band. Cool northerly winds will move in along and
behind this front as it passes through each island. This frontal
boundary will diminish into a trough and stall near the Big Island
and Maui from late Tuesday into Wednesday, and then slowly lift
northward as more unstable southerly kona winds begin to develop.
By next week Thursday, the weather pattern changes significantly
with kona winds developing over the islands as a cut off low moves
into the region. Heavy rainfall and thunderstorms impacts are
possible from Thursday into Friday as this system passes quickly
through the region. Model solutions are still trying to settle on
the track and intensity of this next potentially impactful
rainfall event. Island by island impacts will depend heavily on
the track and intensity of next weeks system. Thunderstorms and
periods of heavy rain for some islands should be expected.
Flooding threats are possible as some heavy rain bands or
thunderstorms may train over one or two islands. Stay tuned for
more details as the forecast time period grows shorter and the
forecast guidance tunes into this potential kona low weather
event.
&&
.AVIATION...
Light to locally moderate trade winds will steer bands of clouds
and light showers off the Pacific towards windward slopes and
coasts. Showers this morning will be most active along east
facing slopes of the Big Island and Maui, but will spread across
windward Molokai and Oahu later today.
The airmass over the state remains unstable. Daytime heating is
expected to drive widespread afternoon convection, especially over
the eastern end of the state. Most recent satellite and radar
imagery indicates moderate to heavy showers lingering just off the
east coast of the Big Island. These showers should taper off in
the next few hours. Heavy showers or thunderstorms will likely
redevelop over Interior and Windward portions of the Big Island
this afternoon.
AIRMET Sierra remains posted for mountain obscuration across east
facing slopes of both the Big Island and Maui. Sierra will likely
be canceled by mid-morning, but conditions could redevelop later
in the day.
&&
.MARINE...
Light to moderate northeast to east winds will persist into
Sunday as a weak surface ridge lifts north of the state. Pockets
of fresh breezes may develop over the typically windier waters and
channels from Maui County to the Big Island during this time.
Moderate to fresh north to northeast winds are expected to return
over the western half of the state late Sunday through Monday,
then extend statewide from Tuesday through Wednesday as another
front moves into the area.
Surf along shores exposed to northerly swells will gradually
lower through the weekend as a north-northwest swell eases.
Offshore buoys to the north and northwest confirm this downward
trend, showing a wide range of short- to medium-period north-
northwest energy. As a result, the surf has fallen below the
advisory level overnight and will dip below average from Sunday
through Monday.
With a blocking high persisting over the northwest Pacific, the
primary swell source will remain out of the north next week,
featuring a mix of short-period wind waves associated with the
northerly winds expected locally and medium-period northerly
swells. Forecast guidance indicates an upward trend in surf
beginning Tuesday and continuing into late next week due to a
potential gale forming well to the north. Heights could near or
reach the advisory level around Wednesday, if this scenario
evolves.
Surf along east-facing shores, not exposed to northerly swells,
will remain small each day due to the lack of trades locally and
upstream.
Surf along south-facing shores will remain around the seasonal
average, with mainly a mix of short-period southeast and an
occasional background south swell moving through.
&&
.FIRE WEATHER...
Wind speeds will remain below critical fire weather thresholds
through the middle of next week. Moisture levels rise swiftly from
Thursday onward with southerly winds bringing another round of
widespread rainfall in the forecast for all islands.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION...Bohlin
AVIATION...Bedal
MARINE...Gibbs
FIRE WEATHER...Bohlin
Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office