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Hawaiian Islands Synoptic Discussion and Guidance |
FXHW60 PHFO 251334
Area Forecast Discussion
National Weather Service Honolulu HI
334 AM HST SAT JUN 25 2016
Strong high pressure far north of Kauai will continue to generate
moderate to breezy trade winds into next week. Numerous showers
early this morning will decrease by midday, as an area of
enhanced moisture embedded in the trades moves west of the state.
Drier conditions are expected from afternoon through the rest of
the weekend, with passing showers favoring windward and mountain
areas, and just a few light showers leeward. The Kona slopes of
the Big Island will continue to see clouds and widely scattered
showers each afternoon and evening.
Showers continue to be quite active across the state early on
this Saturday morning, as an area of enhanced moisture embedded
in the trade winds moves across the state from the east-
northeast. This so-called screaming eagle cloud formation is
associated with a weak low level trough. Mimic-TPW satellite
imagery also clearly shows this feature, with estimated PW values
up to 1.8 inches over the islands. A considerably drier airmass
lies just to our northeast, with estimated PW values dropping off
to around 1.2 inches a couple hundred miles northeast of the
islands. Surface analysis depicts strong high pressure far north
of the state, driving fresh trades over the islands. The 12Z
soundings reflect the enhanced area of moisture moving over the
state, with inversions rising above 10000 feet and PW values
jumping to around 1.5 to 1.6 inches.
Rather wet conditions will continue into the early to mid morning
hours across windward areas, especially over the smaller islands.
Scattered showers will spill over into many leeward areas of the
smaller islands as well. Shower coverage and frequency is expected
to decrease considerably by late morning or midday as the area of
enhanced moisture shifts west of the state and the drier airmass
spreads in from the northeast.
Breezy and relatively dry trade wind conditions are expected from
this afternoon through the remainder of the weekend, as strong
high pressure remains anchored far north of the state, with a dry
and stable airmass in place over the islands. Passing showers will
favor windward and mauka areas, with only a few light showers over
leeward areas. The leeward slopes of the Big Island will continue
to see their usual diurnal pattern of clearing skies late night
and morning, with clouds and widely scattered showers in the
afternoons and evenings.
Little change is expected through the early part of next week,
with moderate to breezy trades prevailing, along with a typical
trade wind shower pattern. A wetter trade wind pattern may develop
by midweek, when models develop a mid level trough near or just
west of the state, and bring an area of enhanced moisture in from
TEMPO MVFR conditions will mainly affect windward and mauka
sections across the island chain through the morning hours as an
area of showery low clouds continues to sweep over the state from
An AIRMET for mountain obscuration is currently in effect for
the north through east sections of all the main islands.
Although the latest ASCAT pass missed the typically windier waters
over Maui County and the Big Island, it did reflect advisory-level
winds over the nearshore waters northwest of Kauai. As a result,
these Kauai waters have been included in the advisory today, which
lines up well with the latest hires model guidance. Elsewhere,
advisory-level winds will continue across the typically windier
zones through tonight across Maui County and the Big Island and may
need to be extended through the remainder of the weekend in later
packages. In addition to the strong trades in these areas, the
latest nearshore wave model guidance depicts maximum seas nearing
advisory levels across the Alenuihaha Channel by Sunday night,
which will need to be monitored as the weekend continues.
Out at the area beaches, rough surf will continue along the east
facing beaches through the weekend and into early next week due to
strong trade winds south of high pressure centered north of the
state. Although the southern Pacific has been active over the past
several days, the bulk of the energy will continue to pass Hawaii
off to the southeast as it heads toward the Americas. After another
small southerly pulse moves through Sunday night through Tuesday
with below advisory-level south shore surf, a decent stretch of
small surf seems likely through the remainder of the upcoming week
and much of the first week of July.
Small Craft Advisory until 6 AM HST Sunday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big
Island Southeast Waters.
Small Craft Advisory until 6 PM HST this evening for Kauai
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