Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
342 AM EDT Fri Jul 15 2022

Valid 00Z Sat Jul 16 2022 - 00Z Sat Jul 23 2022

...Winds and tropical moisture from Darby likely to affect the
islands this weekend...

Guidance offers good agreement with most aspects of the forecast
through the period.  Expect high pressure well north of the state
to support moderate to brisk trades through the end of next week,
with rainfall tending to focus over windward/mountain areas.  The
0300 UTC Central Pacific Hurricane Center advisory shows Hurricane
Darby steadily weakening and passing to the south of the Big
Island as a tropical storm on Saturday.  Darby's passage will lead
to a brief period of stronger winds along with enhanced and more
widespread rainfall.  Then drier air will quickly move in from the
east, leading into multiple days of below-climatology precipitable
water values.  Thus showers should generally be on the light side
once Darby's moisture passes by.

The only guidance discrepancy of note arises during the latter
half of the week when an upper weakness may move over/north of the
area.  There is a fair amount of spread for the shape and position
of the feature.  The 00Z ECMWF brings it farthest west, ultimately
leading to somewhat more moisture reaching the state versus other
guidance by the end of the week.  The CMC is farthest northeast. 
Overall an average of the 00Z GFS/GEFS mean and 12Z ECMWF mean
would provide an intermediate solution.

Rausch