Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
826 AM EDT Fri May 25 2018

Valid 00Z Sat May 26 2018 - 00Z Sat Jun 02 2018

An expansive surface high should stay stretched east-west along
30-35N, and subtropical ridging should remain settled over Hawaii
through Saturday.  The  relatively stable air mass and
precipitable water values near average should favor generally
light windward showers during the first half of the weekend.  

Guidance offers similar pattern evolution themes next week, but
still differ with amplification of a mid-upper level trough and
surface frontal system to the northwest of the state. The latest
ECMWF/UKMET and now GFS/NAVGEM dig this system more than the
Canadian. Overall guidance trends over the past day toward the
more amplified/diggy solution that shows a potential compact
closed low just off Kauai by midweek seems more reasonable
considering the amplitude of the upstream ridge common to most
guidance. An increasing majority of GEFS and ECMWF ensemble
members also support this solution in this vein, bolstering
confidence. Accordingly, slow system approach and proximity would
lead to weakening/veering/moistening trades and much wetter flow
onset and persistence as tropically infused precipitatble water
values increase to near 1.75".

Gerhardt