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RH29 %
WindSSW 2 mph
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Hawaiian Islands Synoptic Discussion and Guidance

252
FXHW60 PHFO 110625
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
825 PM HST Mon Aug 10 2020

.SYNOPSIS...
A high pressure ridge north of the islands will weaken slightly
over the next few days. Moderate to breezy trade winds will
decrease into the light to moderate range from Wednesday onward.
Brief passing showers remain in the forecast, favoring windward
and mountain areas in the overnight to early morning hours.

&&

.DISCUSSION...
The big picture remains unchanged with bands of clouds, shown on
satellite just east of the Hawaiian Islands, drifting in with the
trade winds. Expect a normal increase in shower activity along
windward and mountain areas in the overnight to early morning time
periods. A narrow upper level trough, also known as the TUTT, with
several weak embedded upper lows remains locked in place north of
the state. This upper trough will not impact local shower activity
however it may bring up additional high cirrus clouds into the
region over the next few days.

A high pressure ridge will remain in place north of the islands
through the next seven day forecast period. The ridge will weaken
slightly over the next few days causing trade wind speeds to
decrease into the light to moderate range from Wednesday onward.
Lighter trades may allow weak local scale sea breezes to develop along
the more sheltered western slopes of each island during this time
period. Fairly stable conditions will keep shower activity brief,
the highest coverage for rainfall will linger along windward and
mountain slopes of each island.

Models continue to show good potential for tropical cyclone
development along the tropical convergence zone over the next
five days. This area is currently located 1900 miles east-
southeast of Hilo Hawaii. Details on formation probabilities are
contained in regularly-issued Tropical Weather Outlooks, which
are available at hurricanes.gov, as are forecast advisories for
active tropical cyclones. Stay tuned for updates as the tropical
weather situation evolves over time.

&&

.AVIATION...
Moderate to locally breezy trade wind flow will persist through
Tuesday night. Clouds and scattered showers will continue to
favor north and east coasts, as well as island interiors where
localized sea breezes form. Partial clearing expected across
leeward slopes after midnight due to land breezes. Isolated MVFR
CIG and VIS will occur in passing showers, but VFR conditions are
expected to prevail for all areas.

AIRMET TANGO remains in effect below 8000 feet over and south
thru west of mountains for occasional moderate turbulence.

&&

.MARINE...
High pressure north of the state will keep trade winds in place
through the next 7 days, with only minor fluctuation in speed. As
a result, expected moderate to locally strong trades to persist
through the forecast period. A Small Craft Advisory remains in
effect for the windier waters around Maui and the Big Island
through 6 pm Tuesday.

Moderate to locally strong trades will keep steady surf in place
along east facing shores during the next couple days. A new 10
second period northeast swell is expected to build Wednesday night
and Thursday, hold through Friday, then slowly fade over the
weekend. This will raise east shore surf to above the summertime
average Thursday through Saturday. A small long-period east swell
will be possible over the weekend in association with east Pacific
Hurricane Elida. Only small southerly swells are expected along
south facing shores through the week, with a bit of a bump
possibly raising south shore surf to near the summertime average
over the weekend. North shore surf will remain small through much
of the next week, although some wrap from the northeast swell will
likely bring a bump to surf heights Thursday through Saturday.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 PM HST Tuesday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big
Island Southeast Waters.

&&

$$

DISCUSSION...Bohlin
AVIATION...TS
MARINE...Jelsema

Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office