Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
708 AM EST Thu Jan 10 2019

Valid 00Z Fri Jan 11 2019 - 00Z Fri Jan 18 2019

Today's guidance shows better than average agreement through the
next seven days, favoring a model/mean average to depict forecast
details.  An upper ridge initially to the south and west of the
state will expand over the islands by the weekend and early next
week before collapsing as a progressive shortwave approaches
Thursday.  This ridge will keep frontal boundaries to the north of
the state through the first half of next week.  Meanwhile
precipitable water values will likely remain below climatology
through Wednesday.  The ridging aloft and below average moisture
should keep shower activity on the light side over the next
several days.  High pressure to the north and east of the islands
will promote some background trade flow, and a general windward
focus for any shower activity, but strength may not be enough to
prevent some sea breezes (and associated shower focus) from
developing each afternoon.  By next Thursday the models and
ensemble means show better than average agreement that the
approaching shortwave aloft will bring a cold front and some
organized rainfall into the northwestern islands.

Rausch