Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
801 AM EDT Sun Aug 12 2018

Valid 00Z Mon Aug 13 2018 - 00Z Mon Aug 20 2018

A relatively weak easterly wave will traverse the Hawaiian Islands
through early Mon, continuing a slight increase in windward shower
activity. Otherwise, surface high pressure anchored to the north
of the state should result in continued breezy trades through Tue,
with trades weakening from Wed through later in the weak as the
surface high shifts east and the pressure gradient weakens. Models
continue to show the potential for another wave to reach Hawaii by
next weekend. This second wave also looks to have a much more
significant amount of moisture associated with it, with forecast
PWs in the ECMWF and GFS reaching over 2 inches. At this time,
ensembles are rather tepid in their support for particularly
widespread or heavy rains. Nonetheless, given the increase in
moisture and low-level easterlies associated with the wave, would
expect the potential for at least locally heavy rainfall by next
weekend, especially for the Big Island and Maui.


Ryan