NWS Bulletins for NPAC - MKWC
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Hawaiian Islands Synoptic Discussion and Guidance
203
FXHW60 PHFO 131311
AFDHFO
Area Forecast Discussion
National Weather Service Honolulu HI
311 AM HST Mon Jan 13 2025
.SYNOPSIS...
The potential for heavy showers and isolated thunderstorms will
exist this morning near or over the Big Island, driven by
increasing moisture and an upper disturbance lifting north over
the eastern end of the state. Across the rest of the state, a
typical trade wind pattern will persist through the first half of
the week, with showers favoring windward and mauka areas. However,
trades will weaken in the latter half of the week as an upper
disturbance and a cold front approach, possibly leading to more
widespread rain and thunderstorms.
&&
.DISCUSSION...
Water vapor imagery shows a broad upper low lifting north toward
the Big Island this morning, bringing increasing mid- to upper-
level moisture. The combination of lowering upper heights and
increasing instability, with steepening mid-level lapse rates and
deeper moisture, will keep the threat of heavy showers and
isolated thunderstorms in the forecast today. The highest chances
for this activity will be this morning over the windward/southeast
sections of the Big Island and nearby waters. On the summits,
although chances are low, there could be a brief period of wintry
mix with this activity early this morning. For the rest of the
state, expect typical trade wind conditions, with clouds and
showers favoring windward and mauka sections.
Short-term guidance remains in reasonable agreement through the
first half of the week, showing rising upper heights over the
region as the broad upper low near the Big Island lifts northeast
and dissipates. Trades will gradually weaken into the light to
moderate range later today through midweek as the surface ridge
weakens and shifts southward, following a front passing to the
north. This setup will result in a mainly stable and dry trade
wind pattern, with the best chances for showers in windward and
mauka areas during the night and early morning hours.
Confidence decreases later this week through the weekend due to
diverging model solutions, but there is general agreement on
trade winds being disrupted beginning around Thursday as a cold
front approaches and moves into the area. The increasing moisture
and instability associated with lowering upper heights and the
front will raise the potential for showers and thunderstorms.
&&
.AVIATION...
Winds should trend downward through mid-week with the passage of
a front to the north and another front approaching the islands.
Low cigs and SHRA should favor windward and mauka locations. MVFR
conds expected in SHRA otherwise VFR should prevail.
AIRMET Sierra continues for mtn obsc along windward sections of
the all islands.
AIRMET Tango continues for mod to isol severe upper level turb
from Maui to the Big Island, and will likely be needed through the
morning hours.
&&
.MARINE...
Surface high pressure far northeast of the waters will drive
moderate to fresh trade winds today before easing slightly tonight
as the ridge to the north weakens and a front passes by to the
north. An upper level disturbance south of the Big Island may
bring the potential for thunderstorms over the southern coastal
and offshore waters through the morning hours. A light wind
regime is expected by Thursday through the end of the week as a
potential cold front moves down the island chain.
Surf along north and west facing shores will remain small to
moderate through the morning hours before a moderate long-period
northwest swell is expected to fill in through the day. Guidance
from the ECMWF and observations at NDBC offshore buoy 51101 is
showing a slower arrival than previously forecasted. The High Surf
Advisory (HSA) has been delayed for a start time at noon today
for north and west facing shores of Niihau, Kauai, Oahu, and
Molokai and north facing shores of Maui. The swell is expected to
peak late tonight into Tuesday before slowly declining through the
week.
An even larger, long-period northwest swell that could
potentially bring High Surf Warning level conditions for most
north and west facing shores is expected Friday into Saturday from
a closer, stronger storm that tracks generally towards the
islands over the next few days.
Surf along east facing shores will hold relatively steady today then
continue to decline through the end of the week. A small north
swell could potentially elevate exposed shorelines Wednesday and
Thursday. South shore surf will remain very small through the
middle of the week. An out of season long-period south swell may
move through the islands at the end of the week, bringing a
sizable boost to south shore surf.
&&
.FIRE WEATHER...
No critical fire conditions anticipated during the forecast
period.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory from noon today to 6 PM HST Tuesday for
Niihau-Kauai Leeward-Waianae Coast-Oahu North Shore-Maui
Windward West-Kauai North-Molokai Windward-Molokai North-Molokai
West-Maui Central Valley North-Windward Haleakala.
&&
$$
DISCUSSION...Gibbs
AVIATION...Walsh
MARINE...Shigesato
FIRE WEATHER...Gibbs
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
203
FXHW60 PHFO 131311
AFDHFO
Area Forecast Discussion
National Weather Service Honolulu HI
311 AM HST Mon Jan 13 2025
.SYNOPSIS...
The potential for heavy showers and isolated thunderstorms will
exist this morning near or over the Big Island, driven by
increasing moisture and an upper disturbance lifting north over
the eastern end of the state. Across the rest of the state, a
typical trade wind pattern will persist through the first half of
the week, with showers favoring windward and mauka areas. However,
trades will weaken in the latter half of the week as an upper
disturbance and a cold front approach, possibly leading to more
widespread rain and thunderstorms.
&&
.DISCUSSION...
Water vapor imagery shows a broad upper low lifting north toward
the Big Island this morning, bringing increasing mid- to upper-
level moisture. The combination of lowering upper heights and
increasing instability, with steepening mid-level lapse rates and
deeper moisture, will keep the threat of heavy showers and
isolated thunderstorms in the forecast today. The highest chances
for this activity will be this morning over the windward/southeast
sections of the Big Island and nearby waters. On the summits,
although chances are low, there could be a brief period of wintry
mix with this activity early this morning. For the rest of the
state, expect typical trade wind conditions, with clouds and
showers favoring windward and mauka sections.
Short-term guidance remains in reasonable agreement through the
first half of the week, showing rising upper heights over the
region as the broad upper low near the Big Island lifts northeast
and dissipates. Trades will gradually weaken into the light to
moderate range later today through midweek as the surface ridge
weakens and shifts southward, following a front passing to the
north. This setup will result in a mainly stable and dry trade
wind pattern, with the best chances for showers in windward and
mauka areas during the night and early morning hours.
Confidence decreases later this week through the weekend due to
diverging model solutions, but there is general agreement on
trade winds being disrupted beginning around Thursday as a cold
front approaches and moves into the area. The increasing moisture
and instability associated with lowering upper heights and the
front will raise the potential for showers and thunderstorms.
&&
.AVIATION...
Winds should trend downward through mid-week with the passage of
a front to the north and another front approaching the islands.
Low cigs and SHRA should favor windward and mauka locations. MVFR
conds expected in SHRA otherwise VFR should prevail.
AIRMET Sierra continues for mtn obsc along windward sections of
the all islands.
AIRMET Tango continues for mod to isol severe upper level turb
from Maui to the Big Island, and will likely be needed through the
morning hours.
&&
.MARINE...
Surface high pressure far northeast of the waters will drive
moderate to fresh trade winds today before easing slightly tonight
as the ridge to the north weakens and a front passes by to the
north. An upper level disturbance south of the Big Island may
bring the potential for thunderstorms over the southern coastal
and offshore waters through the morning hours. A light wind
regime is expected by Thursday through the end of the week as a
potential cold front moves down the island chain.
Surf along north and west facing shores will remain small to
moderate through the morning hours before a moderate long-period
northwest swell is expected to fill in through the day. Guidance
from the ECMWF and observations at NDBC offshore buoy 51101 is
showing a slower arrival than previously forecasted. The High Surf
Advisory (HSA) has been delayed for a start time at noon today
for north and west facing shores of Niihau, Kauai, Oahu, and
Molokai and north facing shores of Maui. The swell is expected to
peak late tonight into Tuesday before slowly declining through the
week.
An even larger, long-period northwest swell that could
potentially bring High Surf Warning level conditions for most
north and west facing shores is expected Friday into Saturday from
a closer, stronger storm that tracks generally towards the
islands over the next few days.
Surf along east facing shores will hold relatively steady today then
continue to decline through the end of the week. A small north
swell could potentially elevate exposed shorelines Wednesday and
Thursday. South shore surf will remain very small through the
middle of the week. An out of season long-period south swell may
move through the islands at the end of the week, bringing a
sizable boost to south shore surf.
&&
.FIRE WEATHER...
No critical fire conditions anticipated during the forecast
period.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory from noon today to 6 PM HST Tuesday for
Niihau-Kauai Leeward-Waianae Coast-Oahu North Shore-Maui
Windward West-Kauai North-Molokai Windward-Molokai North-Molokai
West-Maui Central Valley North-Windward Haleakala.
&&
$$
DISCUSSION...Gibbs
AVIATION...Walsh
MARINE...Shigesato
FIRE WEATHER...Gibbs
Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office