Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
718 AM EST Sat Dec 29 2018

Valid 00Z Sun Dec 30 2018 - 00Z Sun Jan 06 2019

A stationary frontal boundary across the western Hawaiian Islands
is expected to linger into Sunday as it washes out. Locally heavy
rainfall will be possible through late Saturday before the best
moisture and instability begin to shift south of the state. As
upper ridging begins to build across/north of Hawaii by Mon-Tue,
drier air should begin to spread across Hawaii, with both the
ECMWF and the GFS showing PWs dropping below one inch by Mon night
or Tue morning. Building high pressure at the surface by this time
will bring a return of moderate trades in the 20-25 kt range.
Ensembles show broad agreement that the upper ridge axis across
Hawaii will persist or even strengthen through next weekend,
bringing a continuation of relatively dry conditions and only very
isolated showers in favored terrain locations.


Ryan