Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
239 AM EST Wed Jan 20 2021

Valid 00Z Thu Jan 21 2021 - 00Z Thu Jan 28 2021

The inverted surface trough that is currently over the western
Islands is forecast to slowly track westward and weaken through
Thursday.  By the end of the week and into the weekend, a strong
surface high builds back in around 40 degrees north.  This will
tend to strengthen the trades with a mainly easterly component to
the flow, and then veers to the east-southeast by Sunday.  This is
in response to another inverted surface trough that should develop
near 170 degrees west in response to a weak upper low, with most
of the rain from this event expected to be west of the Islands. 
However, locally heavy trade wind based showers are likely across
the favored terrain of the Big Island early next week.

Hamrick