Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
342 AM EDT Sat Jun 27 2020

Valid 00Z Sun Jun 28 2020 - 00Z Sun Jul 05 2020

Models and ensembles continue to show a trade wind pattern with a
general windward/mountain shower focus through the period.  Wind
speeds and to some degree rainfall will show some variability with
the passage of features at the surface and aloft.  Trades will
weaken by Sunday-Monday as an upper low tracks well north of the
state and a weakness to the south (reflecting at the surface as a
trough) passes over the area.  Then high pressure covering much of
the eastern half of the Pacific will briefly expand southwestward
while an upper ridge builds over the area from the northeast,
encouraging trades to strengthen for Tuesday-Wednesday.  Trades
will likely weaken again after midweek as the pressure gradient
slackens somewhat and the upper ridge continues off to the west. 
Over the past day the guidance has maintained its relationship for
the westward timing/weakening of the ridge, with GFS/GEFS runs
being faster/weaker than most other guidance.  Prefer maintaining
the majority cluster that is represented by the 00Z ECMWF/12Z
ECMWF mean/00Z CMC mean.  Most rainfall should be in the lighter
half of the spectrum.  The upper weakness passing over the islands
late in the weekend may provide slight enhancement while guidance
shows signals for a pocket of moisture to reach the islands from
the southeast by around Friday or Saturday, which could also
promote at least some increase in rainfall.

Rausch