Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
814 AM EDT Wed Sep 20 2017

Valid 00Z Thu Sep 21 2017 - 00Z Thu Sep 28 2017

The large scale upper-level pattern will feature ridging
west/northwest of the islands, while a persistent weakness camps
out just 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 through the weekend into next week with just a hint
of increasing moisture content at the end of the forecast period.
The strongest trades appear to be the next few days into the
weekend and then relax quite a bit next week. This may be in
response to the active westerlies well to the north with a slight
dip in the jet but the associated frontal zone does not appear to
come close to the northwestern islands. The bottom line is
seasonable weather with trades and windward showers at best for
the next week.

Musher