Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
235 AM EST Wed Jan 27 2021

Valid 00Z Thu Jan 28 2021 - 00Z Thu Feb 04 2021

Drier air will move into the state after midweek with precipitable
water values likely to drop below climatology for a time before
drifting back toward normal during the weekend or early next week.
 High pressure north of the state, with one high center being
replaced by another upstream high toward the end of the week, will
support brisk to strong trades through the weekend.  Thus expect a
primarily windward/mountain focus for showers with rainfall
generally in the lighter half of the spectrum and varying
depending on smaller scale pockets of moisture.  As high pressure
progresses eastward and a cold front approaches Monday, winds
should trend lighter and more southeasterly.  Showers may exhibit
some sea breeze influence by this time.  By Tuesday-Wednesday
guidance agrees that the cold front will reach the islands with a
band of rainfall that could be moderate to heavy.  The primary
discrepancy in the guidance is with the GFS and to a slightly
lesser degree GEFS mean showing faster timing than most other
solutions.  This corresponds to greater amplitude of the upper
trough in the GFS/GEFS mean.  The full array of guidance and
historical GFS fast biases recommend frontal timing that is half
to two-thirds toward the ECMWF cluster at this time. 

Rausch