Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
336 AM EDT Sun Oct 16 2022

Valid 00Z Mon Oct 17 2022 - 00Z Mon Oct 24 2022

Expect a light to moderate trade wind pattern across Hawaii on
Sunday, with a relatively dry airmass and a ridge aloft that
should only lead to limited shower coverage. Trade winds are
likely to lessen for Monday and Tuesday as the typical surface
high north of the state shifts away eastward, and land and sea
breezes could set up in their absence, with cloudiness and perhaps
a few showers in typically favored areas for that pattern.

By around midweek and beyond, the pattern should become more
active and likely wetter, but also increasingly uncertain. Upper
troughing moving across the Pacific is forecast to split energy
off into a closed upper low by Wednesday or Thursday to the north
of the state (perhaps around 30-35N before drifting
southwestward). Model guidance has come into better agreement for
a middle ground position of the upper low compared to the past
couple of days, but differences still remain. The upper low
position will affect the placement of a surface front that is
likely to track through at least some of the islands and then
perhaps stall and dissipate or retreat northward through the
latter part of the week. This front could provide a focus for
moisture and increased coverage of showers around Thursday-Friday,
but it will take additional time to refine details such as which
islands could be the most affected. A moist environment could
remain into next weekend with moisture being pulled north from the
ITCZ. The ECMWF and EC ensemble have been showing this potential
for much above normal available moisture/precipitable water
values, with the GFS/GEFS less so, so this is another aspect of
the forecast that will be monitored.


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