Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
228 AM EST Sat Jan 21 2023

Valid 00Z Sun Jan 22 2023 - 00Z Sun Jan 29 2023

Hawaii and the adjacent coastal waters will likely experience the
effects of two well defined low pressure systems through Tuesday,
even though the main surface lows should be well north of the
state at around 40 degrees north.  The first system is expected to
have a trailing cold front that passes by the far northwestern
Islands by Saturday afternoon, with a plume of enhanced moisture
and heavier rainfall likely affecting those Islands over the
weekend.  The low level winds are expected to veer some to a more
S-SE direction ahead of the boundary as the surface high remains
well east of the state.  By Sunday, the frontal boundary weakens
and attention then turns to the next front/trough approaching the
central and western Islands by Monday night and into Tuesday. 
This will produce a well defined col in the subtropical ridge axis
that may lead to a period of lighter and more variable winds,
followed by stronger northeasterly flow behind the second front
going into the middle of the week, especially northwest of the Big
Island. 

The GEFS and EC means are both indicating the potential for a
closed upper low to form by the end of the week as the amplifying
trough associated with the second cold front mentioned above
builds southward to around 30 degrees north.  The ECENS is closer
to the Islands compared to the more distant GEFS means solution
that is well to the northeast.  Depending on how this evolves and
its location, this could eventually produce impactful weather in
terms of increased rainfall and winds.

Hamrick