Area Forecast Discussion
Issued by NWS Honolulu, HI

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FXHW60 PHFO 290627

Area Forecast Discussion
National Weather Service Honolulu HI
827 PM HST Thu May 28 2020

Breezy trade winds with mainly windward showers are expected
through the weekend. Increasing shower coverage is possible early
next week as enhanced moisture rides in with the trades.


Afternoon soundings from Hilo and Lihue show a strong trade wind
inversion at around 6000 feet with precipitable water values of
1.10 inches (Hilo) and 1.02 inches (Lihue). These values are
slightly below normal and has brought relatively dry trade wind
weather to the state this evening. Rainfall totals over the past
24 hours have been sparse, with majority of the stations reporting
none. Over the next few days, a ridge of high pressure will be
anchored north of the state and will maintain stable and breezy
trade wind weather through the weekend. Off and on light to
moderate showers will primarily be focused over windward areas
during overnight and early morning hours.

Increasing showers are expected sometime early next week as
remnant moisture from an old frontal boundary rides in with the
trade winds. There are still some uncertainty with the timing of
the moisture, but the latest guidance is suggesting around Monday
night. The increase in moisture should bring frequent showers to
windward and mauka areas with showers spilling over toward leeward
areas from time to time. The atmosphere aloft will be stable due
to an upper level high centered north of the state. This should
limit the intensity of the showers, but due to the complex
terrain of the islands, some brief heavy showers will be
possible. Overall though, no significant impacts are expected
during the next week, just some showery trade wind weather
sometime around Monday night through middle of next week.


High pressure remains to the northeast of Hawaii which means the
moderate trade winds will remain in the forecast at least through
this forecast period. Expect most of the shower activity to be
confined to the windward and mauka areas. These showers may result
in mostly passing MVFR conditions for windward and mauka sections
due to lower ceilings and lower visibility. The rest of the state
will have VFR conditions.

No AIRMETs are currently in effect.


High pressure north of the area will maintain northeast to east
trade winds over Hawaiian waters through next week. A high far
northeast of the area will maintain locally strong trade winds
over Hawaiian coastal waters through tomorrow. A Small Craft
Advisory (SCA) is in effect through Friday afternoon for the
windy areas around the Big Island. Winds speeds may briefly drop
below the SCA threshold Friday night as the high moves off to the
southeast. Winds will strengthen again Saturday as a new high
builds north of the area.

A series of swells from the southern hemisphere will maintain
moderate surf along south facing shores through the weekend. A
large south swell building early next week could produce surf
above the High Surf Advisory (HSA) level by Wednesday.

Surf will remain well below HSA levels along other shores. A small
north swell will build Saturday, then fade out on Sunday. A small
northwest swell is expected through mid-week. Surf along east
facing shores will remain quite small.


Small Craft Advisory until 6 PM HST Friday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big
Island Southeast Waters.



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