Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
808 AM EDT Mon Sep 09 2019

Valid 00Z Tue Sep 10 2019 - 00Z Tue Sep 17 2019

Initially brisk trades will trend lighter as mid-latitude high
pressure weakens and an upstream surface ridge stays near near 40N
latitude.  Most models continue to show that the remnants of
Juliette may pass well north of the state during the weekend,
which would also keep the surface gradient over the islands on the
weaker side.  Around Wednesday-early Thursday the 00Z ECMWF brings
higher precipitable water values northward to the Big Island
versus latest GFS/GEFS mean runs and the ECMWF mean.  Otherwise
for most of the week consensus shows values within a standard
deviation of normal and on average slightly below normal.  With
typical differences in detail there is still good agreement that
an area of greater moisture will move into and across the islands
during the weekend into Monday.  Expect relatively light and
primarily (but not exclusively) windward-focused showers for most
of this week followed by a trend toward somewhat higher rainfall
totals this weekend into Monday given the increased deep moisture
as well as heights aloft being lower than they will be early in
the period.  The lighter trades may also allow for more sea/land
breeze influence by this weekend.

Rausch