Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
812 AM EDT Mon Jul 22 2019

Valid 00Z Tue Jul 23 2019 - 00Z Tue Jul 30 2019

Guidance continues to indicate that a surface trough (and possible
embedded low) initially south/southwest of the main islands will
progress northwestward.  The northern fringe of the associated
moisture shield could bring locally enhanced rainfall to parts of
the Big Island and Ni'ihau/Kauai over the next day or so.  For the
rest of the period models differ in specifics but in principle
show lighter windward/mauka shower activity with some fluctuations
in precipitable water values.  Models/ensembles agree well for the
overall pattern through the period with moderate to brisk trades
supported by initial east-central Pacific high pressure that is
reinforced/replaced by an upstream high that strengthens
along/just north of 40N latitude.  There will be an east-to-west
progression of features aloft, with an upper low continuing to
track away from the main islands followed by a ridge building
overhead around Tuesday-Thursday and then an approaching inverted
upper trough (with typical timing spread for a day 6-7 forecast)
late Saturday-Sunday.

Rausch