Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
150 AM EST Fri Jan 15 2021

Valid 00Z Sat Jan 16 2021 - 00Z Sat Jan 23 2021

The weather pattern over the Hawaii domain will initially be
uneventful through this weekend with surface high pressure
centered to the northeast of the state.  There will also be a
slightly weaker than normal pressure gradient, and thus modest
trades that are mainly easterly early in the period, and gradually
veer more towards a southeasterly direction.  Typical trade wind
induced showers should be the rule through Sunday.

Major changes are becoming more likely by the beginning to middle
of next week as an anomalous upper trough, and potentially closed
low, develops near the Islands and moves rather slowly.  This
would result in a noteworthy inverted surface trough and well
developed cold front over the region.  The GFS indicates that the
best tropical moisture surge would likely be east of the Big
Island, whilst the ECMWF is more impactful with periods of heavy
rainfall across the state.  The event could last for a few days
before upper level ridging eventually builds in to the north by
the end of the week.

Hamrick