Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
713 AM EST Mon Jan 14 2019

Valid 00Z Tue Jan 15 2019 - 00Z Tue Jan 22 2019

During the first half of this week expect an already modest
surface ridge just north of the north of the state to weaken
further, resulting in lighter trade winds and increasing potential
for sea breezes to form during the day.  The combination of being
on the northeast periphery of an upper ridge, which will collapse
around midweek, and below normal precipitable water values should
yield relatively light shower activity.

On Thursday winds will become more southerly ahead of an
approaching shortwave aloft and cold front.  Timing of the front
through the northwestern portion of the main islands appears to
have slowed a bit from yesterday.  However by way of faster GFS
trends today's guidance shows better agreement that the front
should extend southeastward beyond the Big Island by early in the
weekend.  A brief period of enhanced rainfall will likely
accompany the front.

Trailing high pressure will bring brisk northerly/northeasterly
winds that will become easterly by Saturday as the high passes by
to the north, supporting a return to primarily windward-focused
showers especially over the Big Island.  Winds will turn
southeasterly and then more southerly on Sunday-Monday with high
pressure settling over the Pacific and another front approaching
from the west.  Slower GFS trends from yesterday have yielded
improved clustering for frontal timing early next week, with
differences now small enough to favor a consensus approach for the
forecast.

Rausch