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Hawaiian Islands Synoptic Discussion and Guidance |
FXHW60 PHFO 151346
Area Forecast Discussion
National Weather Service Honolulu HI
346 AM HST Tue Jun 15 2021
High pressure north of the state will keep moderate to locally
breezy trades in place through Friday, with the trades easing into
the light to moderate range Saturday through Monday as a front
approaches and stalls well northwest of the islands. The remnants
of an old front will bring an increase in shower coverage and
intensity to Kauai and Oahu later this morning through Wednesday,
with rain chances expected to be the highest over windward areas,
particularly on Kauai. A more typical trade wind pattern will
return Wednesday night and hold through early next week, with
showers favoring windward and mauka areas and a few showers
reaching leeward communities from time to time.
Currently at the surface, a 1027 mb high is centered around 950
miles north-northeast of Honolulu, and is driving moderate trade
winds across the island chain early this morning. Infrared
satellite imagery shows quite a bit of high cloud moving overhead,
while the leading edge of a roughly 100 mile wide cloud band (the
remnants of an old front) are evident around 50 miles north of
Kauai and Oahu. Radar imagery shows scattered showers moving into
windward sections of Kauai and over the coastal waters to the
east and northeast of Oahu. Very little shower activity is noted
elsewhere at the moment. Main short term concern revolves around
rain chances associated with the old frontal remnants moving
through during the next couple days.
High pressure will build eastward well to the north of the islands
during the next few days, while a weak disturbance slides westward
well to the south of the state. This will keep moderate to locally
breezy trades in place through Friday. A front is expected to
approach from the northwest Friday night and Saturday, then stall
out several hundred miles northwest of the islands Sunday through
early next week. As a result, we should see the trades ease into
the light to moderate range Friday night and Saturday, and hold at
similar levels Sunday into early next week.
As for the remaining weather details, the old frontal remnants
are expected to bring an increase in showers particularly to
windward sections of Kauai and Oahu beginning later this morning,
with fairly wet trade wind weather then holding through Wednesday,
particularly for Kauai. Showers will favor windward and mauka
areas, but a few showers will also reach leeward communities.
Drier trade wind weather will prevail over Maui County and the Big
Island, with mainly windward showers.
A disturbance aloft will move southward over or just north of the
state Wednesday night and Thursday, then meander in the vicinity
of the islands through early next week. Overall, this should
bring an increase in trade wind shower coverage and intensity
Thursday through early next week. Showers will continue to favor
windward and mauka areas, but the elevated inversions will likely
send a few more showers into leeward areas as well. Additionally,
a thunderstorm or two could develop over the Big Island Thursday
High pressure north of the state will continue to bring moderate
east northeast trades across the islands for the remainder of the
day. Isolated to scattered showers will be mainly limited to
windward locations with brief periods of MVFR ceilings and
visibility possible. Expect VFR conditions and partly cloudy skies
Enhanced low level moisture approaching from the north will bring
increased cloud cover and a chance of showers for Kauai and Oahu
by this afternoon.
No AIRMETS are currently in effect.
High pressure north of the islands will maintain moderate to
fresh trade winds through the week. Showers will increase over the
northern waters today and tonight. Winds will reach Small Craft
Advisory thresholds today around the windier waters near Maui and
the Big Island. Trade winds may decrease over the weekend as a
front develops well northwest of the state.
Surf along south facing shores will remain small through Wednesday,
then slowly rise, approaching High Surf Advisory levels over the
weekend. A short-period north swell will produce small surf along
north facing shores today and diminish tonight and Wednesday. Surf
along north facing shores will be minimal through the rest of the
week, but a small northwest swell is possible early next week.
Trade winds upstream of the islands will produce only small and
choppy surf along east facing shores.
Small Craft Advisory from noon today to 6 PM HST Wednesday for
Maalaea Bay-Pailolo Channel-Alenuihaha Channel-Big Island
Leeward Waters-Big Island Southeast Waters.
Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office
This page is maintained voluntarily by the MKWC and the UHMET faculty, staff, and students.
It was last modified on: Wed, Dec 17 2014 - 1841 UTC
Send comments to: Ryan Lyman