Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
822 AM EDT Sun Apr 15 2018

Valid 00Z Mon Apr 16 2018 - 00Z Mon Apr 23 2018

An upper low will continue to move westward away from Hawai'i late
today into early Monday. Widespread showers and isolated
thundershowers will diminish in intensity and coverage. Drier air
will move in from the northeast especially by late Monday into
Tuesday as another surface high slides eastward just south of 30N.
This will keep trades on the breezy side but with mainly isolated
to scattered light showers in windward/mauka areas. Ensembles show
another surge in precipitable water values on Thursday but the
GFS/GEFS remain wetter than the ECMWF and its ensembles due to a
stronger trough moving just north of the state. Prefer a blended
forecast at this time as the Canadian ensembles mostly support the
ECMWF ensembles. By the end of the week into next weekend, lower
column moisture should decrease per most of the ensembles with the
GFS/GEFS still higher than the ECMWF/EPS. All ensembles show
increasing heights to the northwest of Hawai'i as an upper
ridge/closed high strengthens near the Dateline.

Fracasso