NWS Bulletins for NPAC - MKWC
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Hawaiian Islands Synoptic Discussion and Guidance
667
FXHW60 PHFO 140655
AFDHFO
Area Forecast Discussion
National Weather Service Honolulu HI
855 PM HST Fri Sep 13 2024
.SYNOPSIS...
Locally breezy trade winds will continue into next week, delivering
passing showers that will favor windward areas. Increased moisture
will move over the islands Sunday night and Monday, likely bringing
increased shower coverage, with some heavy showers possible on the
Big Island.
&&
.DISCUSSION...
A lingering low-level trough about 700 miles N of the islands will
move W and finally dissipate this weekend, allowing consolidating
surface high pressure along 40N to drive breezy and locally gusty
trade winds into next week. The trade wind flow is expected to
gradually moisten over the weekend, leading to increased showers
over windward areas occasionally bringing a few sprinkles to leeward
areas through Sunday, especially night and morning.
Model guidance indicates that a sharp 700 mb trough currently about
750 miles SE of the Big Island (from 11N to 18N along ~145W) will
move W and bring a slug of low- and mid-level moisture over the
islands from Sunday night through Monday. Although low-level winds
may only veer slightly to the ESE, the 700 mb flow will become
southerly as the trough passes, leading to moisture extending as
high as 12-15 kft, mainly over the Big Island. With PWAT expected to
exceed 2", the forecast now includes the mention of heavy showers
over windward portions of the Big Island. Afternoon convection over
the Kona slopes may prompt a few heavy showers as well on Monday.
While the moisture increase over the smaller islands is not expected
to be as deep, an increase in windward showers is likely, with low-
level dew points in the low- to mid-70s making it feel muggy
statewide.
After the trough moves W of the islands Tuesday and Wednesday, a
fairly typical trade wind weather pattern is expected. As we
approach the end of the dry season however, we anticipate increased
interruptions to the trade wind flow as the N Pacific storm track
begins to get started. Though confidence is low, guidance has been
trending toward a solution that would lead to decreasing and veering
winds for a short period around the the end of next week, with trade
winds increasing again in about 7-8 days.
&&
.AVIATION...
Moderate to locally breezy trades expected through the weekend. SHRA
and low cigs with brief periods of MVFR conds should be focused over
windward and mauka areas. VFR conds should prevail elsewhere.
AIRMET Sierra is in effect for mtn obsc for windward Big Island.
This may be expanded to other islands with any increase in SHRA.
&&
.MARINE...
Fresh to locally strong trades continue into next week as broad high
pressure develops over the NE Pacific. The Small Craft Advisory
(SCA) remains posted for the typical windier waters of Maui County
and the Big Island through Sunday night. The SCA may eventually
require an extension through the first half of next week as the high
remains nearly stationary.
Rough, choppy surf along east facing shores will return by this
weekend and hold through the first half of next week due to
persistent trades locally and upstream. Offshore buoys are showing a
little more energy in the longer period range which means the small,
long period south-southwest swell will continue to fill in tonight,
becoming slightly more consistent. This swell will generate small
surf along south facing shores over the weekend with a downward
trend expected early next week. North facing shore surf will remain
nearly flat through much of next week. Models show a gale low
developing and tracking along the Aleutian islands early next week
that may send a small northwest swell locally toward the end of next
week.
Water levels at local tide gauges are running over half a foot above
predicted and are expected to reach near or above the 1 foot Mean
Higher High Water threshold Saturday afternoon due to above normal
water levels coinciding with the spring tides. This may result in
nuisance coastal flooding around the peak high tide each afternoon
through Monday. A Coastal Flood Statement will be issued with the
morning package to highlight this threat.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 AM HST Monday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big
Island Southeast Waters.
&&
$$
DISCUSSION...Birchard
AVIATION...Walsh
MARINE...Almanza
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
667
FXHW60 PHFO 140655
AFDHFO
Area Forecast Discussion
National Weather Service Honolulu HI
855 PM HST Fri Sep 13 2024
.SYNOPSIS...
Locally breezy trade winds will continue into next week, delivering
passing showers that will favor windward areas. Increased moisture
will move over the islands Sunday night and Monday, likely bringing
increased shower coverage, with some heavy showers possible on the
Big Island.
&&
.DISCUSSION...
A lingering low-level trough about 700 miles N of the islands will
move W and finally dissipate this weekend, allowing consolidating
surface high pressure along 40N to drive breezy and locally gusty
trade winds into next week. The trade wind flow is expected to
gradually moisten over the weekend, leading to increased showers
over windward areas occasionally bringing a few sprinkles to leeward
areas through Sunday, especially night and morning.
Model guidance indicates that a sharp 700 mb trough currently about
750 miles SE of the Big Island (from 11N to 18N along ~145W) will
move W and bring a slug of low- and mid-level moisture over the
islands from Sunday night through Monday. Although low-level winds
may only veer slightly to the ESE, the 700 mb flow will become
southerly as the trough passes, leading to moisture extending as
high as 12-15 kft, mainly over the Big Island. With PWAT expected to
exceed 2", the forecast now includes the mention of heavy showers
over windward portions of the Big Island. Afternoon convection over
the Kona slopes may prompt a few heavy showers as well on Monday.
While the moisture increase over the smaller islands is not expected
to be as deep, an increase in windward showers is likely, with low-
level dew points in the low- to mid-70s making it feel muggy
statewide.
After the trough moves W of the islands Tuesday and Wednesday, a
fairly typical trade wind weather pattern is expected. As we
approach the end of the dry season however, we anticipate increased
interruptions to the trade wind flow as the N Pacific storm track
begins to get started. Though confidence is low, guidance has been
trending toward a solution that would lead to decreasing and veering
winds for a short period around the the end of next week, with trade
winds increasing again in about 7-8 days.
&&
.AVIATION...
Moderate to locally breezy trades expected through the weekend. SHRA
and low cigs with brief periods of MVFR conds should be focused over
windward and mauka areas. VFR conds should prevail elsewhere.
AIRMET Sierra is in effect for mtn obsc for windward Big Island.
This may be expanded to other islands with any increase in SHRA.
&&
.MARINE...
Fresh to locally strong trades continue into next week as broad high
pressure develops over the NE Pacific. The Small Craft Advisory
(SCA) remains posted for the typical windier waters of Maui County
and the Big Island through Sunday night. The SCA may eventually
require an extension through the first half of next week as the high
remains nearly stationary.
Rough, choppy surf along east facing shores will return by this
weekend and hold through the first half of next week due to
persistent trades locally and upstream. Offshore buoys are showing a
little more energy in the longer period range which means the small,
long period south-southwest swell will continue to fill in tonight,
becoming slightly more consistent. This swell will generate small
surf along south facing shores over the weekend with a downward
trend expected early next week. North facing shore surf will remain
nearly flat through much of next week. Models show a gale low
developing and tracking along the Aleutian islands early next week
that may send a small northwest swell locally toward the end of next
week.
Water levels at local tide gauges are running over half a foot above
predicted and are expected to reach near or above the 1 foot Mean
Higher High Water threshold Saturday afternoon due to above normal
water levels coinciding with the spring tides. This may result in
nuisance coastal flooding around the peak high tide each afternoon
through Monday. A Coastal Flood Statement will be issued with the
morning package to highlight this threat.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 AM HST Monday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big
Island Southeast Waters.
&&
$$
DISCUSSION...Birchard
AVIATION...Walsh
MARINE...Almanza
Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office