Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
752 AM EDT Tue Sep 19 2017

Valid 00Z Wed Sep 20 2017 - 00Z Wed Sep 27 2017

The large scale upper-level pattern will remain rather stationary
with ridging west/northwest of the islands, while a persistent
weakness camps out northeast of the state. The latter feature will
have little impact on Hawaii, as a large dome of surface high
pressure will exist over the eastern pacific and reach into the
tropics. The latest operational versions of the gfs and ecmwf keep
easterly trades intact for the next week with just a hint of
increasing moisture content at the end of the forecast period.
Guidance captures a modest upper trough over the middle of the
pacific to draw tropical moisture north but the associated frontal
zone does not appear to reach the northwestern islands. The bottom
line is seasonable weather with the light to moderate trades and
windward showers at best.

Musher