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Hawaiian Islands Synoptic Discussion and Guidance |
FXHW60 PHFO 051908
Area Forecast Discussion
National Weather Service Honolulu HI
908 AM HST Fri Jun 5 2020
Breezy trade winds will ease somewhat on Sunday and Monday, but will
deliver periods of clouds and showers that will primarily affect
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 that is 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.
Overnight soundings from Lihue and Hilo depict a 8 degree F
temperature inversion between 6500 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 weakening expected Sunday and early next week as
a midlevel trough moves overhead. Trade showers and cloud top
heights would 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.
Strong high pressure in the pacific northeast 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 moist and stable.
Quick moving bands of showers will impact mainly north and east
facing slopes and coasts with isolated spillover showers along
the leeward coasts of the smaller islands. AIRMET Sierra for
mountain obscuration across northeast slopes of the Big Island
will likely be cancelled this afternoon. Conditions may
redevelop late tonight or Saturday morning.
Meanwhile, across Leeward and Interior Big Island, sea breeze
driven cumulus buildups are expected to develop in the afternoon
and persist through the evening hours. Weak land breezes will
promote partial clearing after midnight.
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 today, likely
becoming flat for most beaches. No changes are anticipated into
Small Craft Advisory until 6 PM HST Saturday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big
Island Southeast Waters.
Small Craft Advisory until 6 PM HST this evening for Kaiwi
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
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