Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
719 AM EDT Thu Jun 28 2018

Valid 00Z Fri Jun 29 2018 - 00Z Fri Jul 06 2018

An upper level trough drifts east to a position north of the
islands over the weekend into early next week, when it resumes a
slow westward motion.
In its place a high amplitude north Pacific ridge builds east of
the islands and slowly approaches.

The low level ridge with embedded closed highs drifts north of the
islands
late this week before drifting northeast this weekend and back
north of the islands early next week.

The persistence of the low level ridging results in a uniform
pressure gradient supporting moderate to brisk easterly trades the
balance of this week. This weekend, the high located further away
allows the trades to slacken a bit before picking up next week,
when moderate to brisk trades resume.

The 06Z GFS/GEFS and 00Z ECMWF/ECMWF ensemble mean showed good
agreement on the forecast into next week and a blend of those
solutions is recommended.  Expect mostly windward showers through
the rest of the week, weekend, and into the middle of next week,
with higher totals in windward areas with stronger terrain
gradients.  The one exception is the GFS and ECMWF are now picking
up on a tropical wave moving east to west across the islands early
next week.
An enhancement of showers across the islands would occur if this
comes to fruition.

Petersen