NWS Bulletins for NPAC - MKWC
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Hawaiian Islands Synoptic Discussion and Guidance
478
FXHW60 PHFO 110128
AFDHFO
Area Forecast Discussion
National Weather Service Honolulu HI
328 PM HST Fri May 10 2024
.SYNOPSIS...
The threat for strong to severe thunderstorms and heavy rainfall
will continue across the state tonight as a strong upper level
disturbance settles southward into the area. Although the
thunderstorm potential decreases this weekend, plenty of moisture
lingering combined with afternoon sea breezes and a broad surface
trough nearby will support afternoon showers over interior and
leeward areas each day. The wet pattern could continue through the
latter half of next week as another upper disturbance approaches.
&&
.DISCUSSION...
Water vapor imagery showed broad upper troughing over the region
with a strong shortwave low digging southeastward into the area.
The associated surface trough is located over Kauai with low-level
convergent flow driving the potential for heavy showers and
embedded thunderstorms later today. MUCAPES of 1000 to 2000 J/Kg
combined with effective deep layer shear values of 35 to 45 knots
will support a few strong to severe thunderstorms and locally
heavy rainfall that could lead to flash flooding. As a result, a
Flood Watch remains in effect for the entire state through tonight.
Daytime heating brought sea breeze convergence over the islands
this afternoon resulting in showers and thunderstorms over most
islands today that will linger into this evening. The focus will
shift to Big Island and Maui County later tonight into Saturday
morning, where the high shear potential sets up for more organized
convection capable of producing severe thunderstorms (strong
winds, hail, water and land spouts). However, have added a slight
chance of thunderstorms for tonight across the western half of the
state given the current proximity of the low and radar activity. A
Winter Storm Warning and High Wind Warning are also posted for
Big Island summits due to the high elevation impacts from this
system.
Guidance shows the upper low beginning to weaken as it lifts off
to the northeast this weekend into early next week, which will
support a diminishing likelihood of thunderstorms. The surface
trough will fade and gentle to trades will ease back in by the
end of the day Saturday before weakening again Sunday. The
rainfall chances will likely linger as the aforementioned broad
surface trough remains over or nearby to the west Sunday through
next week. Expect the light to moderate east to southeast low-
level flow to persist, which will allow the land and sea breeze
regime to hold for most areas. This combined with a sufficient
amount of moisture will keep the rainfall chances up each day,
especially through the afternoon and early evening periods over
interior/leeward areas with the sea breezes. The wet pattern could
persist through the second half of the week as another upper low
drops southward into the area drawing up deep tropical moisture
and southerly flow over the state.
&&
.AVIATION...
A broad surface trough and upper level disturbance are moving
southeast across the state. This will bring SHRA and TS activity
through the rest of today into the overnight hours. Expect
periods of MVFR conds with occasional IFR conds possible under
heavier SHRA/TS.
AIRMET Sierra remains in effect for mtn obsc across the smaller
islands and windward Big Island.
AIRMET Tango may become necessary for moderate mid to upper level
turbulence as the upper level disturbance moves across the state.
AMD NOT SKED for PMDY continues due to equipment issues, with no
timeline for restoration.
&&
.MARINE...
Strong to severe thunderstorms will remain possible tonight
through Saturday morning as an unusually strong upper level
disturbance moves across the area. Any thunderstorms that develop
will have the potential to produce strong wind gusts, hail, and
frequent lightning. Marine interests should continue to monitor
for Special Marine Warnings that may be issued through Saturday.
Additionally, as a surface trough that is currently in the Kauai
Channel strengthens and moves across the island chain, light and
variable winds will prevail across local waters, except for within
thunderstorm areas. Light to moderate easterly trade winds will
begin building back into the region on on Sunday.
A long-lived south swell will affect the islands into the
weekend. Recent observations show that surf along south facing
shores has fallen just below advisory levels, so the High Surf
Advisory has been cancelled. Although the swell will continue for
the next several days, surf should slowly trend down as the period
declines. Another series of overlapping, long-period south swells
will give another sizable boost to south shore surf Wednesday
through late next week.
A small, reinforcing short-period north-northwest swell is
building in late this afternoon. This swell will increase north
and west shore surf this evening through Saturday morning, then
decline later Saturday into Sunday. A new small, long-period
northwest swell will build Sunday night, giving north shore surf a
boost early next week. Surf along east facing shores will be well
below normal levels through the middle of next week.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
Flood Watch through late tonight for all Hawaiian Islands.
High Wind Warning until 6 AM HST Saturday for Big Island Summits.
Winter Storm Warning until 6 AM HST Saturday for Big Island
Summits.
&&
$$
DISCUSSION...Foster
AVIATION...Walsh
MARINE...Thomas
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
478
FXHW60 PHFO 110128
AFDHFO
Area Forecast Discussion
National Weather Service Honolulu HI
328 PM HST Fri May 10 2024
.SYNOPSIS...
The threat for strong to severe thunderstorms and heavy rainfall
will continue across the state tonight as a strong upper level
disturbance settles southward into the area. Although the
thunderstorm potential decreases this weekend, plenty of moisture
lingering combined with afternoon sea breezes and a broad surface
trough nearby will support afternoon showers over interior and
leeward areas each day. The wet pattern could continue through the
latter half of next week as another upper disturbance approaches.
&&
.DISCUSSION...
Water vapor imagery showed broad upper troughing over the region
with a strong shortwave low digging southeastward into the area.
The associated surface trough is located over Kauai with low-level
convergent flow driving the potential for heavy showers and
embedded thunderstorms later today. MUCAPES of 1000 to 2000 J/Kg
combined with effective deep layer shear values of 35 to 45 knots
will support a few strong to severe thunderstorms and locally
heavy rainfall that could lead to flash flooding. As a result, a
Flood Watch remains in effect for the entire state through tonight.
Daytime heating brought sea breeze convergence over the islands
this afternoon resulting in showers and thunderstorms over most
islands today that will linger into this evening. The focus will
shift to Big Island and Maui County later tonight into Saturday
morning, where the high shear potential sets up for more organized
convection capable of producing severe thunderstorms (strong
winds, hail, water and land spouts). However, have added a slight
chance of thunderstorms for tonight across the western half of the
state given the current proximity of the low and radar activity. A
Winter Storm Warning and High Wind Warning are also posted for
Big Island summits due to the high elevation impacts from this
system.
Guidance shows the upper low beginning to weaken as it lifts off
to the northeast this weekend into early next week, which will
support a diminishing likelihood of thunderstorms. The surface
trough will fade and gentle to trades will ease back in by the
end of the day Saturday before weakening again Sunday. The
rainfall chances will likely linger as the aforementioned broad
surface trough remains over or nearby to the west Sunday through
next week. Expect the light to moderate east to southeast low-
level flow to persist, which will allow the land and sea breeze
regime to hold for most areas. This combined with a sufficient
amount of moisture will keep the rainfall chances up each day,
especially through the afternoon and early evening periods over
interior/leeward areas with the sea breezes. The wet pattern could
persist through the second half of the week as another upper low
drops southward into the area drawing up deep tropical moisture
and southerly flow over the state.
&&
.AVIATION...
A broad surface trough and upper level disturbance are moving
southeast across the state. This will bring SHRA and TS activity
through the rest of today into the overnight hours. Expect
periods of MVFR conds with occasional IFR conds possible under
heavier SHRA/TS.
AIRMET Sierra remains in effect for mtn obsc across the smaller
islands and windward Big Island.
AIRMET Tango may become necessary for moderate mid to upper level
turbulence as the upper level disturbance moves across the state.
AMD NOT SKED for PMDY continues due to equipment issues, with no
timeline for restoration.
&&
.MARINE...
Strong to severe thunderstorms will remain possible tonight
through Saturday morning as an unusually strong upper level
disturbance moves across the area. Any thunderstorms that develop
will have the potential to produce strong wind gusts, hail, and
frequent lightning. Marine interests should continue to monitor
for Special Marine Warnings that may be issued through Saturday.
Additionally, as a surface trough that is currently in the Kauai
Channel strengthens and moves across the island chain, light and
variable winds will prevail across local waters, except for within
thunderstorm areas. Light to moderate easterly trade winds will
begin building back into the region on on Sunday.
A long-lived south swell will affect the islands into the
weekend. Recent observations show that surf along south facing
shores has fallen just below advisory levels, so the High Surf
Advisory has been cancelled. Although the swell will continue for
the next several days, surf should slowly trend down as the period
declines. Another series of overlapping, long-period south swells
will give another sizable boost to south shore surf Wednesday
through late next week.
A small, reinforcing short-period north-northwest swell is
building in late this afternoon. This swell will increase north
and west shore surf this evening through Saturday morning, then
decline later Saturday into Sunday. A new small, long-period
northwest swell will build Sunday night, giving north shore surf a
boost early next week. Surf along east facing shores will be well
below normal levels through the middle of next week.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
Flood Watch through late tonight for all Hawaiian Islands.
High Wind Warning until 6 AM HST Saturday for Big Island Summits.
Winter Storm Warning until 6 AM HST Saturday for Big Island
Summits.
&&
$$
DISCUSSION...Foster
AVIATION...Walsh
MARINE...Thomas
Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office