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RH10 %
WindE 13 mph
RoadOpen (4x4)
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Hawaiian Islands Synoptic Discussion and Guidance

FXHW60 PHFO 220620

Area Forecast Discussion
National Weather Service Honolulu HI
820 PM HST Tue May 21 2019

A stalled cold front northwest of Kauai will keep the Hawaiian
Islands along the edge of a high pressure ridge through the week.
Expect light and variable winds with land and sea breeze weather
over each island through Friday. Clouds and isolated to scattered
showers will favor mountain and interior sections. Skies will
clear out each night as the stable land breezes begin to develop
after sunset. Trade winds are forecast to return Memorial Day
weekend and last through the first half of next week.


Cloud development over the Hawaiian Islands today was a bit more
on the stable side with less reported shower activity from Kauai
to Maui, while the Big Island reported an increase in light rain
shower coverage today. Hot and humid weather conditions remain
in the forecast through Friday. Two high temperature records were
reported today, Honolulu tied a daily record of 89 degrees
previously set on this day in 2004, and Lihue set a new daily
record high of 87 degrees breaking the old record high temperature
of 86 degrees set on this day in 2004.

The large scale weather pattern remains unchanged with a stalled
front northwest of Kauai, and the edge of a weakened high
pressure ridge lingering over the islands. Light and variable
winds will continue through the week with afternoon sea breezes
developing over all islands interacting with a light background
east to southeasterly flow. Cloud ceilings and isolated to
scattered showers will favor mountains, interior sections, and
sea breeze convergence boundaries from the afternoon into the
early evening hours. Skies will clear out each night and
temperatures will cool off as the stable land breezes develop
after sunset. Global weather models are in good agreement through

Moderate strength trade winds are forecast to return on Saturday.
Clouds and isolated to scattered showers will tend to favor
windward and mauka areas in the overnight and early morning hours.
Drier weather conditions will favor leeward slopes of all
islands. This trade wind weather pattern will likely last through
at least next week Wednesday.


Weak front approaching Kauai will stall tonight, then begin to
retrograde westward away from the Hawaiian Island tomorrow as
high pressure ridging to the northeast begins to strengthen. This
flow pattern will allow for a light southeasterly background flow
to persist across our region. Diurnally driven sea breezes
breezes will dominate coastal areas late Wednesday morning into
Wednesday afternoon. Expect ISOL -SHRA to be mainly concentrated
along the windward coasts and slopes, though a stay shower
remains possible elsewhere.

No AIRMETs are currently in effect.


A surface ridge will persist northwest of the coastal waters while
a front lingers northwest of the offshore waters. Fresh easterly
trade winds will persist south of the Big Island of Hawaii and
through the Alenuihaha Channel, with fresh southeast winds over
Big Island and Maui County windward waters. The southeast flow
will be partly blocked by the Big Island and Maui, so winds around
islands from Lanai to Kauai will be gentle and variable. A high
northeast of the area will strengthen and move southeast slowly.
Winds around the Big Island and Maui will strengthen overnight and
will reach Small Craft Advisory speeds tomorrow. The front and
ridge northwest of the area will slowly shift northwest through
the week. Winds will back out of the east over the smaller
islands by Friday. Then easterly trade winds will persist through
next week.

Small to moderate surf will continue along south facing shores
through Friday. A fairly large swell from southeast of New Zealand
is forecast to reach the coastal waters Saturday. This swell may
produce surf near the advisory level along south facing shores
through Memorial Day. A smaller reinforcing south swell is
possible Tuesday. Surf along north facing shores will be quite
small through Thursday. A moderate northwest swell arriving Friday
will peak Saturday then slowly subside through Memorial Day. A
small north swell is possible for Tuesday. Surf along east facing
shores will remain small through the middle of the week. As winds
strengthen northeast of the area during the second half of the
week, surf will build along east facing shores.


Small Craft Advisory from 6 AM Wednesday to 6 AM HST Thursday
for Alenuihaha Channel-Big Island Windward Waters-Big Island
Leeward Waters-Big Island Southeast Waters.




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