|Wind||NE 16 mph|
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Hawaiian Islands Synoptic Discussion and Guidance |
FXHW60 PHFO 080628
Area Forecast Discussion
National Weather Service Honolulu HI
828 PM HST Tue Jul 7 2020
The breezy trade wind pattern will continue through early next week.
Clouds and showers will favor windward and mountain areas each day,
especially through the overnight and early morning periods as
pockets of moisture move through.
Latest surface analysis and satellite imagery showed the subtropical
ridge anchored north of the islands and patchy low-level clouds
approaching and moving through from east to west. Some of these
clouds are generating showers as they move through - mainly over
windward and mountain areas of Oahu and Kauai this evening. Rain
gages around the islands reflect this and showed peak accumulations
ranging from a quarter to three quarters of an inch over the past 6-
Hrs (through 7 pm HST). Satellite-estimated precipitable water (PW)
imagery depicted no significant changes in moisture over and
upstream of the islands with values ranging from 1.3 to 1.4 inches.
As a result, similar conditions are expected to prevail overnight
into Wednesday, with showers moving through focusing over windward
and mountain locations. Although some will spill over into leeward
areas, these should be brief with minimal accumulations.
Windward shower coverage may increase through the second half of the
week as a mid-level trough moves through from east to west. Model
PWs reflect this and trend up toward 1.6 inches by Thursday as a
batch of higher moisture moves into the area. A combination of this
moisture and breezy trades may be enough for some of this activity
to make it into leeward areas. Drier air will follow beginning
Friday as this moisture and mid-level feature shift west of the
High pressure far northeast of the state will continue to
generate moderate to locally breezy trade wind flow through
twenty-four hours and beyond. Ragged clouds and scattered showers
will impact mainly north and east facing slopes and coasts.
Isolated MVFR CIG or VIS are to be expected in brief showers,
otherwise VFR conditions will prevail all areas.
Weak land breezes will encourage partial clearing across Leeward
Big Island tonight with mostly clear skies expected by morning.
However, light sea breezes and interior cumulus build-ups will
return Wednesday afternoon and linger through the early evening
Fresh to strong trade winds will prevail through the weekend, as
strong high pressure holds in place far north and northeast of
the islands. A Small Craft Advisory (SCA) is in effect for the
typically windier waters around Maui and the Big Island through
Friday. This SCA will likely need to be extended through the
weekend and into next week.
No significant swells are due through much of the week. A mix of
mainly background southerly swells will dominate, with a south-
southwest swell potentially boosting south shore surf to around
the summertime average on Thursday and Friday. Trade wind swell
will gradually build to around summertime average by Thursday or
Friday, then hold into early next week. Surf along north facing
shores will remain small.
Small Craft Advisory until 6 PM HST Friday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big
Island Southeast Waters.
Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office