Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
217 AM EST Wed Dec 25 2024

Valid 00Z Thu Dec 26 2024 - 00Z Thu Jan 02 2025

The model guidance agrees well that the subtropical ridge near and
north/northeast of Hawai'i maintains trade winds for the time
being.  The base of a progressive trough will split the warm core
ridge in two from late Friday onward, as an upper level low cuts
off east to southeast of the Big Island (though closer than seen
on previous days of model runs), causing some relaxation in the
low-level wind flow as a front/shear line moves into the main
islands Friday into Saturday which should briefly provide a focus
for moderate to possibly heavy rain showers Saturday into Sunday
before the boundary fades and retrogrades.  Its fading will be
coincident with a resumption of trade winds as ridging rebuilds
somewhat to the north, moreso at the surface than aloft.  Because
of the closer proximity of the upper level low just to the east of
the Big Island, locally moderate to heavy rains are possible early
to mid next week.

Roth