Area Forecast Discussion
Issued by NWS Honolulu, HI

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FXHW60 PHFO 111351

Area Forecast Discussion
National Weather Service Honolulu HI
351 AM HST Tue Aug 11 2020

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.


Radar imagery this morning shows scattered showers riding into the
islands on the trade winds. 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

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, as are forecast advisories for
active tropical cyclones. Stay tuned for updates as the tropical
weather situation evolves over time.


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.


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 (SCA) remains
in effect for the windier waters around Maui and the Big Island
through 6 pm this evening. Winds will remain close to SCA levels
tonight and Wednesday, so the SCA may need to be extended in time
later today.

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 week, although some wrap from the northeast
swell will likely bring a bump to surf heights Thursday through


Small Craft Advisory until 6 PM HST this evening for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big
Island Southeast Waters.



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