Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
813 AM EDT Fri Mar 18 2016

Valid 00Z Sat Mar 19 2016 - 00Z Sat Mar 26 2016

The model guidance shows excellent agreement with the pattern
across the north Pacific over the next few days.  From Sunday
onward, there are issues across the north-central Pacific well
north of Hawai'i with the 06z GFS/its mean quicker in moving a
small closed low/upper trough along than the 00z ECMWF/its
ensemble mean, but these issues appear to have little consequence
in the front stalling across the Papahanaumokuakea Marine National
Monument Monday into Wednesday and a weak shortwave navigating
around the deep cyclone's base.  The approaching boundary should
weaken the climatological trade winds from late Monday onward and
bring greater moisture into the region, increasing
shower/thunderstorm chances.

The next system in the Westerlies moves near/north of the 40th
parallel across the northwest Pacific.  The 00z Canadian becomes
slow/deep/southward with this system -- its usual bias -- which
causes its front to make lesser progress towards the archipelago. 
Otherwise, the 00z ECMWF/06z GFS and their ensemble means are in
very good agreement aloft with this system, which becomes
negatively tilted by Thursday.  However, the 00z ECMWF has a
leading system Thursday/Friday that drags the front more eastward
into the main islands Thursday.  Prefer a compromise solution
between the 00z ECMWF and 06z GFS for this boundary which fits
their ensemble mean solutions reasonably well.  This boundary
moving in from the west should maintain a heightened
shower/thunderstorm threat into next Friday.

Roth