Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
107 AM EDT Wed Jun 17 2020

Valid 00Z Thu Jun 18 2020 - 00Z Thu Jun 25 2020

A relatively quiet weather pattern appears set to persist across
Hawaii through early next week. High pressure at the surface and
aloft is forecast by all guidance to remain anchored north of
Hawaii, keeping a breezy trade wind pattern in place, with
scattered, primarily windward showers. Models continue to show a
relatively weak easterly wave traversing Hawaii, moving west of
Hawaii by later in the week. A relatively dry air mass in place
(PWs ranging from 1.0-1.5 in.) should keep any associated activity
somewhat sparse, and limit the potential for any heavy rains.
Guidance shows general consensus that as the system moves west of
Hawaii, it should cut off, and perhaps become nearly stationary
for a period of time. The implications for sensible weather across
Hawaii of this seem relatively minor - perhaps a slight weakening
of the trades early Sun-Mon. A continued relatively dry air mass
in place across Hawaii through early next week should keep showers
relatively limited. Deterministic guidance showed some variability
on the handling of the upper low (albeit reduced spread compared
to yesterday), but ensembles continued to show relatively good
agreement, so favor an approach to the forecast heavily reliant on
ensemble means with respect to that feature into next week.

Ryan