Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
732 AM EST Sat Dec 16 2017

Valid 00Z Sun Dec 17 2017 - 00Z Sun Dec 24 2017

...Heavy rain threat next week...

A slow moving upper low will keep conditions unsettled over the
Islands on Saturday, but then the chance for showers should begin
to decrease Sunday into Monday as the low gradually weakens and
lifts northeastward.  The threat for heavy rain is expected to
quickly return Monday night into Tuesday and Wednesday while an
upper trough amplifies aloft and a fetch of deep tropical moisture
reaches the Islands.  Conditions should improve by late next week
once the feed of moisture shunts eastward with the mean trough
axis. 

Model guidance is in fairly good agreement with the large scale
pattern setting up over the Islands this weekend and through next
week.  However, there is still some uncertainty with the details
of the amplifying upper trough, specifically with potential
embedded closed lows.  

Gerhardt