Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
804 AM EDT Mon Jul 10 2017

Valid 00Z Tue Jul 11 2017 - 00Z Tue Jul 18 2017

A prominent mid-level ridge centered over the central Pacific will
dominate the subtropics while weaknesses/retrograding mid- to
upper-lows within the tropics are forecast to gradually slide
westward into Tuesday.  Two of these systems are expected to link
up which will compose a positively tilted upper trough across
Hawai'i from Thursday onward.

At the surface, the subtropical ridge to the north-northeast will
strengthen by a few hPa during the next few days which will
continue to support moderate trades across Hawai`i with its
strength remaining fairly persistent thereafter.  An increase in
the coverage and intensity of shower and thunderstorm
activity/rainfall is likely during the Tuesday through Thursday
time frame as precipitable water values spike considerably
coinciding with the passage of a trough of low pressure moving in
from the east.  The guidance for days has shown precipitable water
values rising to 1.75".  From Friday onward, drier air will work
its way westward bringing conditions closer to average where the
usual windward showers will be favored with heavier amounts in
orographically favored locations.

Roth/Rubin-Oster