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Hawaiian Islands Synoptic Discussion and Guidance |
FXHW60 PHFO 060159
Area Forecast Discussion
National Weather Service Honolulu HI
359 PM HST Fri Jun 5 2020
Breezy trade winds will ease somewhat Sunday and Monday, but will
maintain periods of clouds and showers primarily over windward
and mountain areas.
Clouds and passing showers riding moderate/breezy trade winds
will mainly affect windward and mountain areas, with an occasional
shower reaching leeward locations. High pressure centered far
northeast of the islands extends a ridge along 30N across the
Central Pacific, providing our island trades. Over the weekend
the high will move slowly east turning our winds slightly south of
due east Sunday and Monday. This alignment will allow for lighter
winds over leeward sections of Kauai and Oahu with the Big Island
and Maui County partially blocking the easterly trade winds.
Winds over those eastern islands look to remain at moderate to
locally fresh speeds.
Afternoon soundings from Lihue and Hilo depict a 8 degree F
temperature inversion between 6000 and 9000 feet. This inversion
is capping the trade winds showers, and visible satellite imagery
bears this out showing clouds banking up along the windward
slopes. The strong inversion is expected to remain in place into
the weekend with some weakening expected Sunday and early next
week as a midlevel trough moves overhead. Trade showers and cloud
top heights may increase a notch in response to the weaker
inversion. All that being said, trade wind weather will continue
into the foreseeable future with small/moderate fluctuations in
wind speeds and rainfall.
Breezy to locally strong trade winds will continue through the
weekend over the eastern end of the state, with the Small Craft
Advisory for the typically windy areas around Maui County and the
Big Island having been extended through Saturday. Latest model
guidance shows a weakness developing in the controlling ridge due
to a passing front far north of the area Sunday into Monday, which
could be enough for the trades to trend down into the moderate
category over the western end of the island chain. Trades will
surge back into the breezy to strong category statewide by
Wednesday as robust high pressure sets up north of the state.
Surf along south facing shores will continue to trend down, but
hold steady around the summer average through the weekend as
another long-period pulse fills in by Saturday. This will lower
Sunday into early next week. A small southwest swell is expected
by Wednesday from recent activity across the Tasman Sea. Surf will
respond and rise, but should remain below advisory levels from
Surf along east facing shores will remain small and choppy due to
moderate to breezy trades, locally and upstream across the
eastern Pacific. An upward trend is likely through the second half
of next week as the trades ramp up.
Surf along north facing shores will trend down, likely becoming
flat for many beaches tonight into Saturday. No changes are
anticipated into next week.
Strong high pressure in the northeast pacific will continue to
generate moderate to breezy trade winds across the Hawaiian
Islands. AIRMET TANGO remains in effect below 8000 feet south
through west of mountains due to occasional moderate mechanical
The air mass over the state remains mostly moist and mostly stable.
Diurnal heating has been encouraging low topped cumulus
development over island interiors during the day. Partial clearing
expected across Leeward Big Island overnight where weak land
breezes are expected to replace light sea breezes after sunset.
Elsewhere, expect shower activity to remain focused over
mountains and northeast facing coastlines through twenty-four
hours and beyond.
Isolated MVFR CIG and VIS are to be expected in brief showers.
Otherwise, VFR conditions will prevail through the period.
Small Craft Advisory until 6 PM HST Saturday 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
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It was last modified on: Wed, Dec 17 2014 - 1841 UTC
Send comments to: Ryan Lyman