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Hawaiian Islands Synoptic Discussion and Guidance |
FXHW60 PHFO 260625
Area Forecast Discussion
National Weather Service Honolulu HI
825 PM HST Mon May 25 2020
Lighter winds and mostly dry weather are expected through Tuesday,
with just a few showers, mainly during the afternoon and evenings.
Trade winds are expected to strengthen by Wednesday, and remain in
place into next weekend, delivering brief showers to windward areas.
Varying amounts of benign high clouds are expected to move over the
islands from Tuesday into Friday.
Light E-SE winds will continue into Tuesday, but will strengthen and
turn toward the ENE by Wednesday as a surface ridge just N of Kauai
moves N. Moderate to occasionally breezy trade winds are then
expected to prevail through next weekend, delivering low clouds and
showers to windward areas that will favor the overnight and morning
hours. However, there remains a chance for afternoon sea breezes to
fuel some clouds and showers over leeward and interior areas of
the smaller islands for one more day before winds increase.
Although a low aloft passing S of the islands will send varying
amounts of high clouds over the islands from Tuesday into Friday, a
mid-level ridge will keep the island atmosphere stable, limiting
shower intensity and coverage. Even so, the daily afternoon and
evening cloudiness that forms over leeward Big Island will drop some
showers, with a chance for briefly moderate to heavy showers.
A weak east-northeast to west-southwest oriented surface ridge is
north of the islands early this evening. The close proximity of this
feature to the area is keeping the background flow light out of the
east or east-southeast across the state. This weather pattern will
allow the development of local land breezes over the individual
islands tonight. This may clear out some of the lingering low clouds
over leeward sections of the state. However, some low clouds and
brief showers will be possible along windward coasts and slopes.
There could be brief MVFR conditions in some of these showers, but
VFR conditions will likely prevail across most of the state through
With the light background wind pattern, expect local sea breezes to
develop by late Tuesday morning across most of the state. This may
cause clouds with a chance of showers over leeward and interior
sections of the islands Tuesday afternoon. Some of the heavier
showers might produce brief periods of MVFR conditions, but again
VFR conditions are expected to prevail across most sections of the
No AIRMETs are in effect at this time, and none are anticipated
through Tuesday morning.
Light to moderate east-southeast winds will hold into Tuesday over
the western end of the state, which will allow land and sea breezes
to develop near the coasts. Farther east over Maui County and the
Big Island, moderate to fresh trade winds are expected. Fresh to
strong trade winds are forecast to return by Wednesday statewide as
the ridge retreats northward and strengthens. Winds may reach Small
Craft Advisory levels across the typically windy waters around the
Big Island and Maui Wednesday into the weekend.
Surf along north facing shores will gradually trend down Tuesday as
the small, medium-period, north-northwest swell fades. An upward
trend is expected Wednesday through the second half of the week due
to a storm-force low that has developed around 1000 nautical miles
north-northwest of the state. This swell will shift around out of
the north late Thursday through Saturday as the source passes to the
north tonight through Tuesday. For the extended, guidance depicts
low pressure developing over the far northwest Pacific near the
western Aleutians with strong breezes setting up over a large area
within the 300-330 degree band relative to the islands. If this
materializes, a small northwest swell will be a possibility around
Surf along south facing shores will remain small into midweek with
mainly a combo of south-southwest and south-southeast energy moving
through. An upward trend is anticipated by Thursday night as a new,
long-period, south-southwest swell arrives. This will hold through
Friday, then gradually trend down over the weekend.
For the extended, latest analysis showed 962 mb low pressure passing
south-southeast of New Zealand today. Satellite data reflected this
and showed a large area of gales within Hawaii's swell window in
this area and seas reaching the 28 to 32 ft range. WAVEWATCH III
shows this source building at Pago Pago Thursday night through
Friday with a peak expected there through the day Saturday. This
translates to an arrival in Hawaii through the day Monday and a peak
centered around the Wednesday time frame of next week.
Surf along east facing shores will remain small through the weekend.
Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office
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It was last modified on: Wed, Dec 17 2014 - 1841 UTC
Send comments to: Ryan Lyman