Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
713 AM EST Fri Dec 28 2018

Valid 00Z Sat Dec 29 2018 - 00Z Sat Jan 05 2019

A cold front evident in satellite imagery early this morning a few
hundred miles west-northwest of Hawaii is expected to reach the
western islands later today before stalling and lingering into the
weekend as it washes out. Deep moisture pooled in the vicinity of
the front will result in an increase in convective activity,
particularly across the western islands. Heavy rainfall will be
possible across Kauai through Friday afternoon before the best
moisture begins to shift farther southward. As upper ridging
begins to build across/north of Hawaii by early next week, 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 the end of next week, bringing
a continuation of relatively dry conditions and only very isolated
showers in favored terrain locations.


Ryan