Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
829 AM EDT Thu Nov 01 2018

Valid 00Z Fri Nov 02 2018 - 00Z Fri Nov 09 2018

As the upper level trough continues to lift northeast away from
Hawai'i, conditions have become drier and the flash flood threat
diminished. Light trade winds have returned which will encourage
showers on the windward side of the islands. Meanwhile, ensembles
still agree on a closed upper level low drifting southwest toward
the Hawai'ian islands and will be centered over the island chain
by Sunday morning. This will bring higher precipitable water
values and increase the chance of rainfall, especially on the Big
Island, through the weekend. The atmosphere will be unstable
enough that there could be embedded thunderstorms within this
activity. By Monday, ensembles show the upper low meandering away
from Hawai'i--lingering to the northeast before getting absorbed
into an incoming trough. Precipitable water values will dip once
again, bringing the typical windward trade showers back through
the first half of the week. By Thursday, this upper level trough
will begin to approach Hawai'i.  At the surface, an occluded front
with PW values upwards of 1.5-2 inches will be to the west of the
islands. The 06Z GFS is faster with this system versus the 00Z
ECMWF; the 00Z ECENS ensemble mean is flatter with the surface
feature than the 06Z GEFS mean, but both show some feature to the
west of the islands by Thursday morning.


Reinhart