|Wind||NE 14 mph|
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Hawaiian Islands Synoptic Discussion and Guidance |
FXHW60 PHFO 301952
Area Forecast Discussion
National Weather Service Honolulu HI
952 AM HST Sat May 30 2020
A trade wind weather pattern can be expected through the weekend
and on through all of next week. Passing showers will favor
windward and mauka areas over the next few days with generally
dry weather over most leeward locations. An increase in showers is
expected Tuesday and Wednesday as moisture associated with an old
frontal boundary interacts with island terrain.
High pressure is centered several hundred miles north northwest
of the state. This places the islands in a moderate trade wind
environment. The high will remain nearly stationary through Sunday
night then move off to a position far northeast of the area late
Monday through Wednesday. The will result in a slight decrease in
trade wind speeds. The high is then forecast to rebuild due north
of the area Thursday and Friday with an expected uptick in trade
The airmass is rather dry and stable with an upper ridge centered
several hundred miles to our north. Pockets of moisture embedded
in the trades will provide for some light passing showers over
windward and mauka areas with most leeward locations remaining
generally dry. Moisture associated with the remnants of an old
front are forecast to move through the area during the Tuesday
through Wednesday time frame. An increase in shower activity is
expected especially over windward and mauka a areas.
A strong ridge of high pressure north of the state will keep
moderate, mostly dry trade winds in place through twenty four
hours and beyond. Shower activity will be limited and focused
mainly over north and east facing slopes and coasts. Light sea
breezes are expected to develop across Leeward Big Island this
afternoon and generate inland cumulus build-ups that will persist
through the evening hours.
Isolated MVFR CIG and VIS are to be expected in brief showers.
Otherwise, VFR conditions will prevail all areas. No AIRMETs are
currently in effect or anticipated at this time.
A high to the N will maintain moderate to locally fresh trade
winds through the weekend, with winds near Small Craft Advisory
(SCA) criteria in the windier areas, especially the Alenuihaha
Channel. The trades will weaken Monday as the high moves NE, but
will rebuild Wednesday as the high strengthens.
A S swell is expected to gradually build from Monday into Wednesday,
then gradually diminish into Friday. Peak surf heights are
expected to be large enough to warrant a High Surf Advisory (HSA)
for S facing shores of all islands, potentially as early as
Tuesday, but more likely Wednesday. Surf will remain well below
HSA levels along other shores through the period, although a
couple of small swells from the N and NW will keep surf from going
flat along N facing shores. The recently updated Surf Discussion
(SRDHFO) contains details on the swell sources.
Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office